Dome epithelial M cells dissociated from rabbit gut-associated lymphoid tissues

Dome and dome epithelial cells were selectively dissociated from gut-associated lymphoid tissues of rabbits. Sequential tissue washes in dithiothreitol, EDTA, and collagenase removed the dome epithelium, without disrupting the follicles or villi, and provided a cell suspension containing 74 +/- 6% lymphocytes, 9 +/- 4% columnar epithelial cells, 10 +/- 7% tangible-body macrophages, and 4 +/- 2% M cells (follicle-associated epithelial cells). The last mentioned cells were characterized by transmission electron microscopy as large (20 to 55 microns diameter) cuboidal, round, or oval cells with eccentric nuclei and thin membranous processes surrounding empty vacuoles. The M cells were occasionally joined together by tight junctions. Histochemical and immunocytochemical analyses of M cells with the light microscope showed that they were devoid of immunoglobulins and negative for T-cell antigen and secretory component and had no detectable alkaline phosphatase or endogenous peroxidase activity. The M cells had few vacuoles with faint acid phosphatase activity; nonspecific neutral esterase was abundant. Possible uses for dome and dome epithelial cells are discussed.