Determination of leucocyte extracellular traps (ETs) in seminal fluid (ex vivo) in infertile patients—A pilot study

Leucocytospermia has been associated with loss of sperm function. Extracellular traps (ETs) of leucocytes are produced during innate immune response. ETs can be activated by spermatozoa in contact with polymorphonuclear (in vitro), inducing sperm entrapment and decrease motility. In this pilot study, we describe the results of ETosis ex vivo, in seminal fluid (SF) smear of infertile patients, associating ETs with leucocytospermia and bacteriospermia. In 21 infertile patients, semen parameters (WHO, 2010), microbiological study, leucocytospermia and presence of ETs in SF were determined. Leucocytes (CD45, CD15 and CD68) were evaluated by immunostaining in SF smears. Indirect immunofluorescence (global histone and H4‐citrullinated 3) and scanning electron microscopy (SEM) were used to determine ETs morphology. In 28.6% of patients presented leucocytospermia without bacteriospermia, all of them presented a large number of ETs in the SF smears examined. About 76.6% of the patients without leucocytospermia were positive for ETs. Samples with leucocytospermia have a higher number of ETs and would be related to the amount of leucocytes in the SF. The morphological predominant ETs were diffuse (diffETs) and spread (sprETs). The formation of ETs indicates leucocyte activation in semen, and it was observed that ETosis does not depend exclusively on the presence of bacterial contamination.