Tissue-Specific Populations of Leukocytes in Semen-Producing Organs of the Normal,Hemicastrated,and Vasectomized Mouse

Abstract

Semen HIV is separate and distinct from blood HIV and work has revealed that seminal plasma HIV particles do not arise from infected cells in semen. These findings indicate that semen-producing organs contain multiple, separate populations of HIV host cells. To test this hypothesis, we have examined leukocytes in semen-producing organs of male mice. Cells expressing F4/80 (tissue-specific macrophage marker) were abundant in testicular interstitium and as dendritic-like cells in the lumenal epithelium of the epididymis, especially the initial segment. Cells expressing CD45 (panleukocyte marker) were found rarely in the testicular interstitium, commonly in epididymal epithelium, were most abundant in the interstitium of the epididymis, and were more readily released from minced tissues than were F4/80⁺ cells. Unlike the testis and epididymis, F4/80⁺ cells in seminal vesicles also appeared to be CD45⁺. Seminal vesicle leukocytes were restricted to the epithelium surrounding the lumen and were not released by mincing. CD11b (monocyte/B cell marker) was detected in testicular and seminal vesicle interstitium, but not in the epididymis. Hemicastration and vasectomy caused a limited redistribution of the leukocytes. These findings confirm the existence of tissue-specific populations of leukocytes in semen-producing organs and indicate that some populations are highly tissue adherent. The regionalized, tissue-adherent macrophages in the testicular interstitium, the initial segment of the caput epididymis, and the seminal vesicle epithelium suggest the existence of reservoirs of HIV-infected cells in humans that could contribute virus particles, but not infected cells, to semen and possibly blood.