Phenotypic and functional analysis of oral mucosal macrophages

Oral mucosal macrophages were prepared in single cell suspensions from the oral mucosa of BALB/c mice and isolated by adherence to glass. Adherent cells were identified on the basis of morphological, cytochemical, phenotypical, and functional characteristics and compared with peritoneal adherent cells. Adherent cells were found to be esterase positive and could perform non immune phagocytosis. From immunofluorescence studies it was found that about 30% of oral adherent cells bear macrophage differentiation (Mac 1) and Ia antigens, whereas the F4/80 marker could not be detected. The presence of Ig receptors was assessed by the binding of IgA and IgG-coated fluorescent microspheres; distinct populations of mucosal macrophages were shown to display IgA and IgG receptors (25% each) with a significant percentage of double-bearers (15%). The effector functions of these Ig receptors was verified by opsono-phagocytosis of live lactobacilli. Murine oral mucosal tissue appears to host a heterogeneous population of resident macrophages including IgA-dependent phagocytic cells which would be particularly well suited for immune defense functions at secretory sites.