Genital mucosa is the main portal of entry for various incoming pathogens, including human immunodeficiency virus (HIV), hence it is an important site for host immune defenses. Tissue-resident memory T (T_RM) cells defend tissue barriers against infections and are characterized by expression of CD103 and CD69. In this study, we describe the composition of CD8⁺ T_RM cells in the ectocervix of healthy and HIV-infected women.

Study samples were collected from healthy Swedish and Kenyan HIV-infected and uninfected women. Customized computerized image-based in situ analysis was developed to assess the ectocervical biopsies. Genital mucosa and blood samples were assessed by flow cytometry.

Although the ectocervical epithelium of healthy women was populated with bona fide CD8⁺ T_RM cells (CD103⁺CD69⁺), women infected with HIV displayed a high frequency of CD103⁻CD8⁺ cells residing close to their epithelial basal membrane. Accumulation of CD103⁻CD8⁺ cells was associated with chemokine expression in the ectocervix and HIV viral load. CD103⁺CD8⁺ and CD103⁻CD8⁺ T cells expressed cytotoxic effector molecules in the ectocervical epithelium of healthy and HIV-infected women. In addition, women infected with HIV had decreased frequencies of circulating CD103⁺CD8⁺ T cells.

Our data provide insight into the distribution of CD8⁺ T_RM cells in human genital mucosa, a critically important location for immune defense against pathogens, including HIV.