Rabbit Peyer's patches, appendix, and popliteal lymph node B lymphocytes: a comparative analysis of their membrane immunoglobulin components and plasma cell precursor potential.

We have characterized and compared the differentiative potential of B lymphocytes obtained from rabbit appendix (APP), Peyer's patches (PP), and popliteal lymph nodes (PLN) by immunofluorescence analysis of membrane immunoglobulin (Ig) components, by radioiodination of membrane components followed by isolation and identification of cell surface Ig, and by cell transfer studies. As assessed by cell transfer lymphoid cells from PP and APP appear to be highly enriched sources of IgA plasma cell precursors. In addition, these populations of lymphocytes have a small but significant potential to give rise to IgM and IgG plasma cells. In contrast, as shown previously (1), lymphocytes from PLN have a comparatively small potential to generate IgA plasma cells. The ability of cells from PLN and PP to give rise to plasma cells is correlated with the presence of 35 to 38% of lymphocytes from both sources having membrane light chain determinants detectable by immunofluorescent staining. When the cells were stained directly for mu chain determinants, about 33% of PLN cells and 28% of PP cells were positive. These latter percentages were shown to reflect cells bearing both endogenously synthesized b4 light chain and mu heavy chain. By indirect immunofluorescence, alpha and gamma chain determinants were also detected on PP and PLN cells; however, these Ig did not appear to be products of the cells which bore them as they were not regenerated after removal of Pronase. It was further demonstrated that purified rabbit copro-sIgA and colostral sIgA are cytophilic for PP and PLN cells. The results are discussed with respect to the origin of IgA plasma cells and the postulated bursal role of mammalian gut-associated lymphoid tissue.