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Clinical Chemistry 46: 1387-1394, 2000;
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(Clinical Chemistry. 2000;46:1387-1394.)
© 2000 American Association for Clinical Chemistry, Inc.

Articles

Determination of Total Interleukin-8 in Whole Blood after Cell Lysis

Jochen Reinsberg1,a, Jörg Dembinski2, Christoph Dorn1, Daniela Behrendt2, Peter Bartmann2 and Hans van der Ven1

Departments of
1 Gynecological Endocrinology and Reproductive Medicine, and
2 Neonatology, University of Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany.
a Address correspondence to this author at: Zentrum für Frauenheilkunde und Geburtshilfe, Universität Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany. Fax 49-228-2874651.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Background: It has been shown that a high percentage of interleukin-8 (IL-8) in blood is cell associated. Recently, a simple method for determination of cell-associated IL-8 in whole blood after cell lysis has been described. The purpose of this study was to evaluate this method, to examine the influence of preanalytic sample handling, and to establish the concentration range of total IL-8 and its relation to age and sex in healthy subjects.

Methods: Total IL-8 content of whole blood was determined after lysing blood cells with Milenia® cell lysis solution. IL-8 in the resulting blood lysate was measured with the IMMULITE® IL-8 immunoassay.

Results: When freshly drawn blood was stored up to 48 h on ice, no significant changes in total IL-8 were measured in the subsequently prepared lysate, whereas with storage at room temperature, total IL-8 increased after 3 h from 94 ± 13 ng/L to 114 ± 16 ng/L (n = 10). In lysate stored for 48 h at 4 °C, marginal changes of the IL-8 concentration were noted, with storage at room temperature, only 76% ± 5% (n = 12) of initial concentration was recovered. From lysate frozen at -20 and -80 °C, respectively, 84% ± 4% and 93% ± 2% of initial IL-8 was recovered after 70 days (n = 10). IL-8 was measured with comparable precision in plasma (CV, 3.2–4.2%) and blood lysate (CV, 3.7–4.1%). When plasma was diluted with cell lysis solution, a slightly overestimated recovery (125% ± 3%) was observed; for lysate specimens with a cell lysis solution content >=75%, the recovery after dilution was 98% ± 2%. In lysate prepared from 12 blood samples with exogenous IL-8 added, IL-8 recovery was 104% ± 2% (recovery from plasma <35%). The median total IL-8 in blood lysates from 103 healthy subjects (22–61 years) was 83 ng/L of blood (2.5–97.5 percentile range, 49–202 ng/L of blood). In females but not in males, total IL-8 increased significantly with advancing age (P <0.002). We found grossly increased total IL-8 in six pregnant women with amniotic infection syndrome.

Conclusions: The evaluated method allows the assessment of total IL-8 in blood with good performance when appropriate conditions of sample pretreatment are considered. The values in healthy volunteers all were above the detection limit of the IL-8 assay; therefore, slight changes of total IL-8 could be noted. Thus, the present method is a suitable tool to study the diagnostic relevance of total IL-8 in blood.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Interleukin-8 (IL-8), a cytokine that plays an important role in inflammation, is produced by monocytes/macrophages (1)(2)(3) as well as by many other cell types, such as endothelial cells (4)(5) or fibroblasts (6). IL-8 is a potent chemoattractant factor for polymorphonuclear neutrophils and can stimulate many activities of these cells (7). Since various immunoassays have become commercially available for IL-8, there have been a growing number of reports dealing with the diagnostic relevance of the concentration of IL-8 in blood. It has been shown that the plasma IL-8 of patients with sepsis syndrome correlates with the severity of the disease (8)(9), and IL-8 is suggested to be an early immunological marker for predicting the onset of multiple organ failure after injury (10)(11). The IL-8 concentration in plasma may give information concerning the outcome in patients with severe burns (12) or in patients undergoing coronary artery bypass grafting (13), and IL-8 is proposed as a marker for bronchitis (14). However, it has been shown that in addition to the circulating IL-8, which is measured in serum or plasma, a high percentage of IL-8 in blood is cell associated: IL-8 binds to the Duffy antigen on the surface of erythrocytes (15)(16) as well as to specific high-affinity receptors on most of the leukocytes (17)(18)(19). Until now there has been little information about the diagnostic relevance of cell-associated IL-8. Kalfin et al. (20) observed significantly increased concentrations of cell-associated IL-8 in patients undergoing cardiopulmonary bypass grafting, whereas no plasma IL-8 was detected. In cancer patients, treatment with IL-1{alpha} caused a transient increase of plasma IL-8, whereas the erythrocyte-bound IL-8 concentrations were substantially higher than those measured in plasma and remained increased long after the plasma concentrations had become undetectable (21). de Winter et al. (22) showed that the IL-8 released in plasma after acute myocardial infarction subsequently binds to erythrocytes, producing a transient increase in plasma IL-8 and a more prolonged increase of erythrocyte-bound IL-8. In septic patients, high concentrations of IL-8 were found in blood lysate, which were up to 40-fold higher than the concentrations measured in plasma (23). Altogether, the data suggest that total IL-8 may provide additional information for assessment of inflammatory processes.

A simple method for determining cell-associated IL-8 was described by Marie et al. (23), who measured the IL-8 concentration after lysing blood cells with detergents. Recently, a cell lysis solution became commercially available that is offered for preparation of blood cell lysate and determination of total IL-8 by the IMMULITE® IL-8 enzyme immunoassay performed fully automated on the IMMULITE system (DPC Biermann). This cell lysis solution is composed of a commonly used cell culture medium supplemented with a suitable detergent. The detergent concentration is optimized in such a way that all blood cells are solubilized but the binding of the analyte to the assay antibodies is not affected. In the present study, we tested to what extent preanalytic sample handling can influence the IL-8 concentration in blood lysate and evaluated the analytical performance of total IL-8 determination with the IMMULITE IL-8. In addition, we determined the concentration range of total IL-8 measured in blood lysates from healthy subjects. Finally, we present preliminary data that suggest that the total IL-8 concentration is considerably increased in pregnant women with an amniotic infection syndrome compared with uncomplicated pregnancies.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
patients and samples
Blood samples were drawn onto sodium EDTA from the following subjects after informed consent: For determination of the reference range of total IL-8, blood was collected from 103 healthy subjects (46 males and 57 females) who underwent routine examination by a company physician. None of the females was pregnant. In addition, blood was collected from 15 healthy women with uncomplicated pregnancies between gestational weeks 20 and 39. All blood samples were drawn between 0800 and 1200 and immediately stored on ice; if not otherwise mentioned, blood samples were processed within 3 h after collection. In addition, ~150 routine specimens submitted to the clinical laboratory for hematological examination were analyzed. All specimens were collected in accordance with the guidelines of the University of Bonn Ethics Committee for the use of humans in research.

sample processing
For determination of total IL-8, a blood cell lysate was prepared from each EDTA blood sample: an 0.1-mL aliquot of the native EDTA blood was mixed with 0.1 mL of Milenia® cell lysis solution (DPC Biermann) and incubated in stoppered 1.5-mL polypropylene tubes for 10 min at room temperature. The resulting lysate was used for IL-8 measurements without further centrifugation. From the remaining EDTA blood, the plasma was separated by centrifugation at 2000g for 10 min. To prepare lysate samples with increased cell lysis solution content for dilution studies, the original lysate samples were prediluted two- to fourfold, producing a cell lysis solution content >=75%. If not otherwise mentioned, plasma and lysate specimens were measured immediately after preparation.

determination of il-8
IL-8 was measured with the enzyme immunoassay IMMULITE IL-8 (test code, I8; DPC Biermann) performed fully automated on the IMMULITE system. For a single determination, a total volume of 0.15 mL was required (0.05 mL sample volume + 0.1 mL void volume). The detection limit of the assay is ~5 ng/L (standardized in terms of the National Institute for Biological Standards and Controls Reference Preparation 89/520). Gross hemolysis, simulated by adding packed red blood cells to plasma samples, had no effect on the values measured with the IMMULITE IL-8 (IL-8 values measured by manufacturer in samples without red blood cells added, 115, 353, and 3055 ng/L; after 30 mL/L red blood cells were added, the values were 113, 346, and 3137 ng/L).

sample storage experiments
The influence of storage conditions on EDTA-whole blood was studied in 10 healthy volunteers: 10 mL of EDTA blood was aliquoted into 1.5-mL polypropylene tubes (1-mL aliquots); the aliquots were stored at room temperature or on ice prior to preparation of plasma and lysate, respectively; after the desired storage time (0, 0.5, 1, 2, 3, 5, 11, 24, and 48 h) plasma and lysate were prepared from one of the aliquots and analyzed immediately or stored at 4 °C and analyzed not later than 3 h after preparation. To investigate the influence of storage conditions on the IL-8 concentration of the lysate samples, lysate obtained from individual EDTA blood samples was aliquoted into 1.5-mL polypropylene tubes (0.2-mL aliquots) and stored for different periods at room temperature, at 4 °C, or frozen at -20 and -80 °C. To study the effect of freezing, 0.2-mL aliquots of the lysate specimens were subjected to repeated freeze-thaw cycles: after freezing for 1 h at -20 °C, the aliquots were thawed for 30 min at room temperature; subsequently, the samples were frozen again or analyzed immediately.

evaluation of analytical performance of il-8 measurements in blood lysate
For assessment of the imprecision of the IL-8 assay, between-day CVs were calculated from replicate determinations of two commercial control samples (IMMULITE Cytokine Control; DPC Biermann) on 25 days. To investigate to what extent the precision of IL-8 determinations was affected by the lysate preparation procedure, CVs were calculated from the IL-8 values measured in replicate lysate specimens (n = 20) prepared from three individual blood samples. For assessment of the linearity of dilution, the IL-8 concentrations measured in lysate or plasma samples diluted with Milenia cell lysis solution were compared with the expected values. In addition, the recovery from plasma or lysate of a known amount of IL-8 added to EDTA-whole blood specimens was determined: 0.035 mL of the high IL-8 calibrator provided by the manufacturer for recalibration of the IMMULITE IL-8 assay (IL-8 concentration, 4500 ng/L) was added to 0.7 mL of EDTA blood and incubated for 20 min at room temperature. Blood lysate and plasma was then prepared as described above, and the resulting IL-8 concentration was measured. Recovery was expressed as percentage of the amount added.

statistical analysis
Values from repeated measurements of the same samples after different treatments were compared by the nonparametric Friedman two-way analysis of variance. Differences between two or more groups were evaluated using the Mann–Whitney rank-sum test and the Kruskal–Wallis one-way analysis of variance, respectively. Deviation from a hypothesized value was tested by the Wilcoxon sign-rank test. Correlation between two variables was assessed by the Spearman rank correlation test. P <=0.05 was considered statistically significant. All statistical calculations were performed using BMDP statistical software.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
storage of whole blood prior to plasma/lysate preparation
When EDTA-whole blood samples (n = 10) were preincubated at room temperature, the total IL-8 concentration measured in the subsequently prepared lysate increased from 94 ± 13 ng/L of blood to 114 ± 16 ng/L of blood after 3 h and up to 3170 ± 727 ng/L of blood after 48 h of preincubation; no significant changes in total IL-8 were observed when the whole blood samples were preincubated on ice (Fig. 1 ).



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  		Figure 1. Total IL-8 measured in blood lysate prepared from blood samples (n = 10) preincubated at room temperature ({square}) or on ice ({blacksquare}) up to 48 h.

Total IL-8 is expressed as percentage of control values measured immediately after blood sampling. Values are given as means ± SE (bars); *, P <0.05 vs control.

In most of the plasma samples prepared from the preincubated blood samples, no IL-8 was detectable; only after a 48-h incubation at room temperature were increased IL-8 concentrations (16–284 ng/L) measured.

storage of blood lysate
To investigate the stability of IL-8 in blood lysate, the IL-8 concentrations measured in lysate specimens from different subjects immediately after preparation were compared with the values measured after storing the lysate at room temperature, at 4 °C, or frozen at -20 and -80 °C, respectively. Only marginal changes of the IL-8 concentration were observed after storage of the lysate at room temperature up to 4 h and at 4 °C up to 48 h; however, further incubation for 24 and 48 h at room temperature led to a significant decrease of the IL-8 recovered (Fig. 2A ). The effect of long-term storage on the IL-8 concentration of lysate samples frozen at -20 and -80 °C, respectively, is shown in Fig. 2B . At -20 °C, no changes of the IL-8 concentration were noted for up to 20 days; however, after storage for 40 and 70 days, the recovery of IL-8 was significantly reduced. When the lysate samples were stored at -80 °C, a modest but significant reduction of the IL-8 concentration was noted only after 70 days. The IL-8 concentration in the lysate was not affected by up to five freeze-thaw cycles (mean recovery after five cycles, 106% ± 4%; n = 10).



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  		Figure 2. Effect of storage duration on the recovery of IL-8 from blood lysate samples (n = 12) stored at room temperature (RT) or at 4 °C (A) and stored frozen at -20 or -80 °C (B).

Values are given as means ± SE (bars); *, P <0.05 vs control.

analytical performance of il-8 measurements in blood lysate
Two commercial cytokine controls (IL-8 concentration, 109 and 489 ng/L) were measured, with between-day CVs of 4.2% and 3.2% (n = 25). The CVs calculated from the IL-8 values measured in 20 blood lysate specimens prepared from three individual EDTA blood samples (total IL-8 concentration, 74, 231, and 327 ng/L of blood) were 3.7–4.1%.

We also examined the extent to which changes of sample matrix produced by the addition of the cell lysis solution during preparation of blood lysate might affect the values measured with the IMMULITE IL-8 assay. Fig. 3 shows the effect of dilution of plasma or lysate samples with the cell lysis solution on the apparent IL-8 concentration measured with the IMMULITE IL-8 assay. The IL-8 concentrations recovered after twofold dilution of 11 plasma samples (IL-8 concentration, 13–145 ng/L) were significantly higher than the expected values (mean recovery, 125% ± 3%; P <0.01), whereas for 7 lysate samples (IL-8 concentration, 32–191 ng/L) with a 50% cell lysis solution content, the recovery was only slightly increased (mean recovery, 108% ± 2%; P <0.05) and for 9 lysate specimens (IL-8 concentration, 47–154 ng/L) with increased cell lysis solution content (>=75%), the IL-8 concentrations recovered met the expected values quite well (mean recovery, 98% ± 2%). To exclude that the overestimation of recovery after dilution with cell lysis solution was attributable to residual contamination of plasma samples with blood cells, five samples were retested after additional high-speed centrifugation (12 000g for 10 min). However, the recovery after dilution was not normalized in the centrifuged samples (mean recovery without additional centrifugation, 119% ± 6%; recovery after high-speed centrifugation, 123% ± 7%).



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  		Figure 3. Recovery of IL-8 after dilution with cell lysis solution.

IL-8 recovery was measured in native plasma specimens (containing no cell lysis solution; •), native blood lysate specimens (containing 50% cell lysis solution; {blacksquare}), and blood lysate specimens with increased cell lysis solution content (>=75%, prepared by two- to fourfold predilution of native lysate specimens with cell lysis solution; {square}) after twofold dilution with cell lysis solution.

The recovery of IL-8 added to EDTA-whole blood samples, as measured in plasma or lysate, is shown in Table 1 . Whereas only a small portion (<35%) of IL-8 could be recovered from the plasma obtained from 12 individual blood samples to which the IL-8 calibrator solution had been added, the recovery from the lysate was 104% ± 2%. The recovery of IL-8 from lysate was independent of the hemoglobin concentration of the blood samples.


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  		Table 1. Recovery of IL-8 added to whole EDTA blood.1

il-8 values in healthy volunteers
The concentration range of total IL-8 was determined in the lysate prepared from EDTA blood samples of 57 healthy females (median age, 35 years; range, 22–56 years) and 46 healthy males (median age, 35 years; range, 25–61 years) without any medication. Although in most cases no IL-8 could be detected in the plasma of these volunteers (detectable plasma IL-8 concentrations ranging from 5.1 to 11.9 ng/L were measured in only nine cases), the concentration of total IL-8 measured in the blood lysates was 45–230 ng/L of blood with a median of 83 ng/L of blood and a 2.5–97.5 percentile range of 49–202 ng/L of blood. The values did not follow a gaussian distribution but were skewed toward lower values (Fig. 4 ).



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  		Figure 4. Total IL-8 in healthy subjects.

Frequency distribution of total IL-8 measured in blood lysate from 103 healthy subjects (46 males and 57 females); age range, 22–61 years.

When the entire population of healthy subjects was considered, the total IL-8 values in females were only slightly higher than in males, without reaching significance (Table 2 ). However, when only subjects older than 35 years were analyzed, the sex-related difference became significant (P <0.02). In the subgroup <=35 years, the total IL-8 concentrations measured in males and females were identical and only slightly lower than the values observed in older men. Correspondingly, in females but not in males, a significant correlation between total IL-8 and age was observed (P <0.002).


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  		Table 2. Total IL-8 in healthy volunteers.1

total il-8 in pregnant women
As summarized in Fig. 5 , the total IL-8 concentrations found in 15 healthy women with uncomplicated pregnancies (gestational weeks 20–39) were within the range of values found in nonpregnant women with a slightly increased median (130 ng/L of blood; range, 66–208 ng/L of blood). In contrast, in six patients (gestational weeks 24–27) with an amniotic infection syndrome, the total IL-8 concentration was significantly increased, whereas in plasma no IL-8 could be detected.



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  		Figure 5. Total IL-8 measured in blood lysate from 15 healthy women with uncomplicated pregnancies ({diamondsuit}) and 6 pregnant women with an amniotic infection syndrome ({diamond}).


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
There has been an increasing number of reports indicating a pathogenic role of IL-8 in inflammatory and infectious diseases (8)(9)(10)(11)(12)(13)(14)(24)(25)(26). As such, increased concentrations of plasma IL-8 have been observed during several inflammatory events (8)(9)(10)(11)(12)(13)(14). However, because most blood cells can bind IL-8, a high percentage of the total IL-8 in blood is cell associated, and the free IL-8 concentration that can be measured by immunoassay reflects only a small portion of the total IL-8 content of blood (15)(22)(23). Thus, it seems important to examine the relationship between total IL-8 in blood and the course of disease. In the present study, we measured the total IL-8 concentration after lysing blood cells with detergents, as described previously by Marie et al. (23), using a commercial cell lysis solution. Our data demonstrate that the total IL-8 concentration of a blood sample can be altered significantly by preanalytic sample handling. The total IL-8 especially is affected by the storage conditions of whole blood from the time of collection until further processing. When blood is stored at room temperature, additional IL-8 is produced by blood cells, leading to a considerable increase of total IL-8. It is well known that cytokines such as IL-8 can be produced in whole blood cell culture ex vivo upon stimulation of whole blood by bacterial toxins (7)(23)(27). Furthermore, it has been reported that even without exogenous toxin stimulation, long-term storage of red blood cell concentrates for several weeks can lead to an increase of cytokine concentrations (28)(29). The present results indicate that most of the IL-8 produced during storage at room temperature is cell associated, so that an increase of total IL-8 becomes visible after a few hours of storage, whereas the free IL-8 concentration in plasma remains below the detection limit. We noted no production of cell-associated or free IL-8 by blood cells when the whole blood had been stored on ice. However, as reported by Stack et al. (28), ex vivo production of IL-8 cannot be abolished completely by cold storage conditions. Thus, we recommend that for determination of total IL-8, blood samples should be stored on ice or at least at 4 °C not more than 2 days from the time of collection until lysate preparation.

As expected, no additional IL-8 was produced after blood cells were lysed. The concentration of IL-8 in the lysate was quite stable. Only when lysate was stored at room temperature did the IL-8 concentration decrease significantly, whereas in the refrigerated lysate, the IL-8 concentration dropped only marginally within 2 days. As reported for other cytokines (30), repeated freezing had no effect on the lysate IL-8 concentration. Thus, lysate samples can be stored frozen. Inasmuch as a significant decrease in the IL-8 concentration was observed in lysate samples frozen at -20 °C for 40 days, whereas at -80 °C no changes were noted, long-term storage should be at -80 °C or colder. However, the present results indicate that a slight decrease in IL-8 also occurs after 2 months at -80 °C.

The present data demonstrate that the analytical performance of IL-8 measurements in blood lysates with the IMMULITE IL-8 is quite good. As already reported by others, the IL-8 concentration can be measured with high precision in serum or plasma; the CV values obtained in this study for the control samples agree very well with those reported previously (31). However, we also obtained comparable CV values for the determination of the total IL-8 concentration in blood lysate, indicating that the precision is not affected by the lysis procedure. As shown by the recovery studies, most of the exogenous IL-8 added to whole blood samples is absorbed rapidly by blood cells or is otherwise bound so that it is not accessible for measurement with the immunoassay. This is in agreement with the observations of Marie et al. (23), who found 94–96% of exogenous IL-8 associated with blood cells. After blood cells were lysed, the added IL-8 became completely available for measurement. The fact that the recovery of IL-8 in the lysate was not affected by the hemoglobin concentration of blood samples indicates that there are no interferences by hemoglobin with the IMMULITE IL-8 assay. This is in agreement with the results of the manufacturer, who found no interferences when simulating gross hemolysis. Thus, the present method really makes possible the assessment of the total IL-8 concentration of a blood sample. However, there might be a restriction in the method inasmuch as dilution of plasma with the cell lysis solution produces a slightly overestimated recovery of IL-8. The fact that the overestimation of recovery after dilution with cell lysis solution was significantly diminished in lysate samples with a sample matrix already containing 50% cell lysis solution and was completely absent in lysate samples with further increased cell lysis solution content indicates that the deviation from linearity is attributable to the change of sample matrix, which is most prominent in plasma samples. This is confirmed by the results of Berthier et al. (31), who found a good linearity of dilution when the appropriate sample diluent was used. In every case, to ensure the comparability of results, the same parts of the cell lysis solution should be used for all samples.

Altogether, the evaluated method enables the measurement of the total IL-8 concentration in blood with good performance when appropriate conditions of sample pretreatment are considered. Whereas the free IL-8 concentration in plasma of healthy volunteers in most cases was below the detection limit of the IL-8 assay, the total IL-8 concentration was never <45 ng/L of blood. Thus, the entire reference range of total IL-8 can be assessed so that slight increases could also be noted. This makes it possible to demonstrate an age-associated increase of the total IL-8 concentration in women, whereas the free IL-8 in plasma cannot be measured. Recently, increased production of the proinflammatory cytokine IL-6 with advancing age has been reported by several authors (32)(33)(34)(35). It has been claimed that the increase of IL-6 is a consequence of the "normal" aging process, which reflects an age-associated dysregulation of the immune system and which may contribute to several pathologic conditions that accompany old age (33). The increase of total IL-8 demonstrated in the present study may be interpreted as a further event resulting from a dysregulation associated with the aging of the immune system.

Interestingly, we found only in females a significant increase of total IL-8 with advancing age, indicating sex-related differences in the regulation of IL-8 production. The existence of sex-related differences in cytokine concentrations seems to be quite plausible in view of findings that sex hormones obviously take part in the processes responsible for the age-related changes of the cytokines. As reported by Daynes et al. (33), in aging mice increased IL-6 production can be reversed by supplementing the animals with dehydroepiandrosterone sulfate, a hormone that decreases with aging but is significantly higher in men than in women at all ages (36). Furthermore, salivary IL-6 is higher in postmenopausal women on estrogen therapy than in premenopausal women (37). In addition, IL-8 production seems to be associated with the estrogen status inasmuch as in estrogen-deficient women higher concentrations of IL-8 have been found in the gingival crevicular fluid than in estrogen-sufficient patients (38). Finally, an association of IL-8 with the function of the reproductive system in females is suggested by the fact that IL-8 can induce follicular growth in mice (39). Altogether the data implicate that the production of IL-6 as well as IL-8 is modified by the sex hormone status.

Sex-related differences in age-associated changes of the IL-6 concentration have been studied by Wei et al. (32). However, in contrast to our results for total IL-8, these authors observed a significant increase of the IL-6 concentration in males but not in females. On the other hand, McKane et al. (34), who studied a greater number of subjects covering a broad age range, found a threefold increase of IL-6 concentrations in women during the aging process. The results imply that the age-associated increase of IL-6 occurs in men as well as in women but is modified by the sex hormone status. In the present study, we also observed in men a slight increase of total IL-8 that did not reach significance. To clarify whether for total IL-8 there is a sex-independent increase with advancing age that is modified by sex hormones, a greater number of healthy men need to be tested.

The preliminary results measured in pregnant women indicate that there are only moderate effects of pregnancy on the total IL-8 concentration. However, in patients with amniotic infection syndrome, we observed grossly increased concentrations of total IL-8. These results suggest that the total IL-8 concentration may be useful as a diagnostic marker for intraamniotic infection. Several markers have been suggested for detection of intraamniotic infection, including C-reactive protein and IL-6 in maternal serum, and IL-8 in maternal urine (40)(41)(42)(43). To what extent the determination of total IL-8 in maternal blood may provide additional information, leading to improved detection of intraamniotic infections, has to be clarified in further studies.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

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