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/inflammation such as seminal leukocytes, and with semen quality in a prospective study. All patients were asymptomatic for genital tract infection. A comprehensive semen evaluation included sperm analysis, sperm migration testing, antisperm antibody screening, immunocytochemical round cell differentiation to determine seminal leukocytes counts and the leukocyte ratio, complement 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 outcome of the sperm migration test (motile sperm harvested after a swim-up procedure). IL-8 concentrations were significantly correlated with leukocyte counts per ml (P < 0.0001) and per ejaculate (P < 0.0001), and with the leukocyte ratio (P < 0.001). All leukocytospermic samples had high IL-8 concentrations (< or =2 ng/ml). The SP concentration of IL-6 was 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-inflammatory cytokines with semen quality. The significant association with seminal leukocytes and other potential inflammation markers suggests that IL-8 might be used as sensitive marker for silent male genital tract infection.