Serum level of soluble tumor necrosis factor receptor II (sTNF-R75) is apparently an index of overall monocyte-related infectious and inflammatory activity

Background: The serum level of soluble tumor necrosis factor receptor II (s TNF-R75) has been recently found to correlate with the activity and/or seve rity of several different infectious and inflammatory diseases. These resul ts have led us to presume that the serum sTNF-R75 level reflects the active immune activity of all causes and may correlate well with nonspecific infe ctious and inflammatory markers such as peripheral leukocyte counts and ser um C-reactive protein level. Methods: In total, 110 apparently healthy adul ts, 55 men and 55 women, were enrolled in the study. Serum levels of sTNF-R 75, C-reactive protein, globulin, alkaline phosphatase, lactate dehydrogena se, creatinine, urea nitrogen, and counts of neutrophils, lymphocytes, mono cytes, eosinophils, and basophils were checked. The relationships between t he serum sTNF-R75 level and other parameters were analyzed using the SAS st atistical program. Results: By various statistical methods, the serum sTNF- R75 level showed consistently significant positive links with peripheral mo nocyte count, serum C-reactive protein level, and two parameters of renal c learance function (serum urea nitrogen and creatinine levels). Serum levels of alkaline phosphatase and lactate dehydrogenase had significant positive links with the serum sTNF-R75 level by multivariate regression analysis. T here was no significant link between the serum sTNF-R75 level and counts of neutrophils, lymphocytes, eosinophils, or basophils. Conclusions: Our resu lts, together with those of recent reports showing positive correlations be tween the serum sTNF-R75 level and activities/severities of different infec tious and inflammatory diseases, and also that TNF-alpha is principally pro duced by monocytes and macrophages, suggest that the serum sTNF-R75 level i s very probably an index of overall monocyte-related infectious and inflamm atory activities.