(010) INTERPLAY OF SEMINAL MICROBIOTA AND LEUKOSPERMIA: A ROLE FOR IMMUNOLOGIC TOLERANCE

Abstract Introduction Leukospermia is of poorly understood clinical significance. Culture-based assays have not consistently correlated leukospermia with bacteriospermia. DNA-based microbial detection has revealed a rich microbiome throughout the body, often in areas previously presumed sterile, and certain microbial populations have been linked to impaired fertility. Objective We aim to evaluate the relationship of leukospermia and male infertility by conducting a retrospective study in infertile men with high numbers of seminal round cells, using a DNA-based bacterial detection assay and flow cytometry. Methods We identified all patients within our semen repository with at least 10 round cells per high-power field (or 2 million cells/mL) from January 2022 to October 2023. Microbiome profiling was performed with real-time PCR using one of the only commercial assays of the genital microbiome, which, although not specific to semen, has significant overlap with seminal microbial communities and the capacity to detect clinically relevant microbial taxa (Applied BiosystemsTM TaqMan® Vaginal Microbiota assay). Seminal leukocyte analysis was performed by flow cytometry. Chart review was performed to abstract demographic and clinical data. Results Of 850 patients screened, 17 met inclusion criteria. 7 samples contained detectable bacterial DNA, which did not correlate with round cell count nor motility (P ≥ 0.11). The most common species identified were Lactobacillus iners (4 patients) and Enterococcus faecalis (4 patients), both of which have been linked with impaired fertility. Leukocyte analysis revealed lower frequencies of tolerogenic CD4 T regulatory cells in samples with detectable microbes (10.0%) vs. undetectable (26.9%), although this was not significant (P ≥ 0.18). Conclusions We present microbiota data on a relatively large series of patients with seminal round cells. Despite DNA-based testing, our results do not correlate leukospermia with bacteriospermia. This suggests a possible non-microbial, immunological etiology of impaired fertility. Although preliminary, our complementary leukocyte data suggest bacterial colonization may impair immunologic tolerance in the reproductive tract and subsequently impair fertility. Prospective studies of leukospermia samples utilizing 16S rRNA sequencing are needed to comprehensively characterize this subset of the seminal microbiome. Disclosure No.