Langerhans cells, macrophages and lymphocyte subsets in the cervix and vagina of rhesus macaques

Abstract

Background: The lower reproductive tract is an important site of contact with pathogenic microorganisms and local immune responses to a variety of antigens have been reported. The purpose of this investigation was to define the morphology of the mucosa-associated lymphoid tissue in the genital tract of rhesus monkeys.

Experimental design: Monoclonal antibodies were used in an immunoperoxidase staining technique to identify immunophenotypic markers on mononuclear cells in the vaginal and cervical mucosa of 14 cycling, multiparous rhesus macaques.

Results: CD1a+ Langerhans cells were present in the stratified squamous epithelium of the vagina (14 animals) and ectocervix (11 animals). Surprisingly, CD1a+ dendritic cells were also found within the columnar epithelium of the endocervix (5 animals). Moderate numbers of CD68+ macrophages were located in the submucosa of the vagina, ectocervix, and endocervix of all the monkeys. In all of the animals, moderate numbers of CD8+ lymphocytes were present in the submucosa and squamous epithelia of the vagina and ectocervix. Variable numbers of CD20+ B cells and CD4+ lymphocytes were located in the submucosa of all the areas examined. Lymphoid nodules were present in the submucosa of vagina (14 animals) and ectocervix (4 animals), and these nodules contained macrophages, CD4+ T cells and B cells, with fewer numbers of CD8+ T cells and Langerhans cells.

Conclusions: These observations provide a morphologic basis for mucosa-associated lymphoid tissue in the female genital tract. Langerhans cells in the vaginal mucosa and endocervix may be well suited to sample antigen in the lumen of the reproductive tract, travel to the draining lymph node, present the antigen to T lymphocytes and initiate an immune response. This pathway of antigen presenting cell migration from the mucosa to the genital lymph node may represent the inductive arm of the mucosal immune system in the lower female reproductive tract.