Date Approved


Graduate Degree Type


Degree Name

Biomedical Sciences (M.H.S.)

Degree Program

Biomedical Sciences

First Advisor

Dr. Christopher Pearl

Second Advisor

Dr. James Christopher Reed

Third Advisor

Dr. Kristin Renkema

Academic Year



Genetically-modified mice lacking the leptin hormone (Ob) or leptin receptor (Db) have reduced testosterone and decreased sperm production leading to infertility. Leptin receptors are also expressed by immune cells, suggesting leptin can regulate immune responses. Recent studies have focused on identifying the immune cells present within the epididymis and found cells expressing markers typically associated with dendritic and macrophage cells. These cells likely function against infection and to induce tolerance to sperm. The effects of leptin on the immune system and the presence of immune cells within the epididymis raises the possibility that alterations in the immune cell profile and/or function may contribute to the infertility observed in leptin-altered mice. The purpose of this study was to investigate potential differences in the epididymal immune cell profile in normal, Ob, and Db mice. The epididymis was collected from C57, Ob and Db mice at 16 weeks of age (n=6 per group) and divided into three regions (IS/caput, corpus, and cauda). Each region was processed for incubation with antibodies to innate immune cell markers (CD11b, CD11c, F4/80) or adaptive immune cell markers (CD4, CD8, CD19) and counted by flow cytometry. The percentage of CD8+ cells was significantly lower in the cauda of Ob and Db mice compared to the C57 mice. In all groups of mice, the percentage of CD11b+ cells was highest in the IS/caput and significantly lower in the cauda. Within each region, the percentage of CD11b+ cells was similar between all mouse models. The largest population of CD11b+ cells was also CD11c+ and F4/80+, though no difference was seen between epididymal regions or genetic backgrounds. The percentage of CD11b+ cells that were CD11c+ and F4/80- was significantly lower in the cauda of Ob and Db mice compared to C57. The percentage of CD11b+ cells that were CD11c- and F4/80+ was significantly lower in the corpus of Ob and Db mice compared to C57. These results suggest that leptin may alter subpopulations of innate immune cells within specific epididymal regions, but the overall profile of innate immune cells, and therefore the response of the innate immune system, is likely unaffected.

Available for download on Wednesday, November 13, 2024

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