Relationship of seminal plasma interleukin (IL)-8 and IL-6 with semen quality

The concentration of interleukin (IL) -8 and IL-6 was determined in seminal plasma (SP) samples from 137 randomly chosen subfertile males to evaluate the relationship with other potential parameters of subclinical infection/i nflammation such as seminal leukocytes, and with semen quality in a prospec tive study. All patients were asymptomatic for genital tract infection. A c omprehensive semen evaluation included sperm analysis, sperm migration test ing, antisperm antibody screening, immunocytochemical round cell differenti ation to determine seminal leukocytes counts and the leukocyte ratio, compl ement fraction C-3 (C-3c) determination, and semen cultures, in aliquots of the same ejaculates. The SP concentration of IL-8 was inversely related to semen quality, e.g. to the total number of motile spermatozoa or to the ou tcome of the sperm migration test (motile sperm harvested after a swim-up p rocedure). IL-8 concentrations were significantly correlated with leukocyte counts per ml (P < 0.0001) and per ejaculate (P < 0.0001), and with the le ukocyte ratio (P < 0.001). All leukocytospermic samples had high IL-8 conce ntrations (<less than or equal to>2 ng/ml). The SP concentration of IL-6 wa s much lower, but was significantly correlated with IL-8 (P < 0.0001). Both IL-8 and IL-6 were significantly related with the C-3c. No association of interleukin concentrations with the bacterial colonization of semen samples was found. The results indicate a marked relationship of some pro-inflamma tory cytokines with semen quality. The significant association with seminal leukocytes and other potential inflammation markers suggests that IL-8 mig ht be used as sensitive marker for silent male genital tract infection.