Human spermatozoa of male patients with subfertility express the interleukin-6 receptor

Male subfertility has been associated with bacterial infections and chronic inflammation. In this context, several studies investigated cytokine levels in seminal plasma, whereas interleukin-6 (IL-6) appears to be crucial. However, little is known about its receptor, the IL-6R expression on human spermatozoa. Thus, the aim of the present study was to screen spermatozoa for IL-6R expression and to identify its localisation. Semen samples of 137 patients (median age 37.69, SD ± 7.82) with subfertility were analysed. Sperm analysis including determination of IL-6 was performed following the World Health Organization criteria. Also, flow cytometry was performed for sperm IL-6R expression. IL-6R⁺ cells were used for immunofluorescence staining to identify receptor localisation. The results showed positive staining for IL-6R in the midpiece of spermatozoa. Furthermore, a significant correlation between sperm IL-6R expression, seminal plasma IL-6 and total sperm count could be demonstrated, whereas a negative correlation was observed in sperm IL-6R expression and motility. However, no statistical significance could be observed between IL-6R expression, vitality and morphology. Moreover, incubation of spermatozoa with IL-6 led to a slight but significant decrease in motility after 24 hr. These data suggest that IL-6R expression may play a role in impaired sperm function during inflammation.