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 (sTNF-R75) has been recently found to correlate with the activity and/or severity of several different infectious and inflammatory diseases. These results 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 infectious and inflammatory markers such as peripheral leukocyte counts and serum C-reactive protein level. Methods In total, 110 apparently healthy adults, 55 men and 55 women, were enrolled in the study. Serum levels of sTNF-R75, C-reactive protein, globulin, alkaline phosphatase, lactate dehydrogenase, creatinine, urea nitrogen, and counts of neutrophils, lymphocytes, monocytes, eosinophils, and basophils were checked. The relationships between the serum sTNF-R75 level and other parameters were analyzed using the SAS statistical program. Results By various statistical methods, the serum sTNF-R75 level showed consistently significant positive links with peripheral monocyte count, serum C-reactive protein level, and two parameters of renal clearance 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. There was no significant link between the serum sTNF-R75 level and counts of neutrophils, lymphocytes, eosinophils, or basophils. Conclusions Our results, together with those of recent reports showing positive correlations between the serum sTNF-R75 level and activities/severities of different infectious and inflammatory diseases, and also that TNF- α is principally produced by monocytes and macrophages, suggest that the serum sTNF-R75 level is very probably an index of overall monocyte-related infectious and inflammatory activities.