title: Mechanisms regulating IgA class-specific immunoglobulin production in murine gut-associated lymphoid tissues. II. Terminal differentiation of postswitch sIgA-bearing Peyer's patch B cells.
abstract: Our previous studies indicated that cloned T cells obtained from Peyer's patches (PP) (Lyt-1+, 2-, Ia+, and H-2K/D+) evoked immunoglobulin (Ig) class switching of PP B cells from sIgM to sIgA cells in vitro; however, these switch T cells could not in themselves provide optimal help for the differentiation of postswitch sIgA-bearing PP B cells to IgA-secreting cells. Thus, in the present report we described studies focused on mechanisms regulating terminal differentiation of the postswitch PP sIgA-bearing B cells. First, to explore the effect of T cell-derived B cell differentiation factor(s) (BCDF) and macrophage factor(s) (MF) on the terminal maturation of PP B cells, LPS-stimulated PP B cells were co-cultured for 7 d with cloned T cells in the presence or absence of the above factors. In the absence of PP cloned T cells the BCDF and MF had only a modest effect on IgA production, whereas in the presence of PP, but not spleen cloned T cells, IgA production was increased. Next, to investigate the effect of T cells derived from a gut-associated lymphoid tissue (GALT), mesenteric lymph nodes (MLN), as well as from spleen on terminal differentiation of postswitch sIgA PP B cells, LPS-driven PP B cells were precultured with the cloned T cells to induce a switch to sIgA, and subsequently cultured with MLN or spleen T cells or a Lyt-2+-depleted T cell subset in the presence of a T-dependent polyclonal mitogen, staphylococcal protein A. Alternatively, in the second culture period BCDF alone was added, instead of T cells and protein A. Here it was found that B cells pre-exposed to switch T cells from PP, but not spleen, were induced to produce greatly increased amounts of IgA in the presence of protein A and T cells or a Lyt-2+-depleted T cell subset as well as in the presence of BCDF alone. Furthermore, in the presence of BCDF alone many B cells expressed cytoplasmic IgA. These observations strongly support the view that the terminal differentiation of postswitch sIgA B cells is governed by helper T cells and macrophages, or factors derived from such cells. Such cells or factors do not affect preswitch B cells.
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D000921:Antibody-Producing Cells / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002999:Clone Cells / Q000276:immunology; D005260:Female; D006133:Growth Substances / Q000502:physiology; D007070:Immunoglobulin A / Q000096:biosynthesis*; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D007376:Interleukin-2 / Q000502:physiology; D015847:Interleukin-4; D008070:Lipopolysaccharides / Q000494:pharmacology; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology*; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010581:Peyer's Patches / Q000166:cytology / Q000276:immunology*; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D006133:Growth Substances; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007376:Interleukin-2; D008070:Lipopolysaccharides; D015847:Interleukin-4