title: On the molecular basis of T helper cell function. II. B-lymphocyte promotor factors: I-A-restricted production and their apparent antigen-independent, direct interaction with B cells.
abstract: The differentiation of Ig+ B cells into plaque-forming cells is dependent on antigen and factors produced by T cells and/or macrophages. We describe here the production of T-cell factors termed lymphocyte promotor factors (LPF). A foetal calf serum-specific T-cell line and its clones synthesize LPF, which is defined as factors that polyclonally stimulate normal spenic T cells to differentiate into cytotoxic T lymphocytes (T-LPF) and normal splenic B cells to differentiate into plaque-forming cells into (PFC) (B-LPF) in the apparent absence of specific antigen. The proliferation of and the B-LPF production of all T-cell clones tested were foetal calf serum-specific and I-Ab-restricted. Some of these clones produced only T-LPF, some clones produced only B-LPF, and some clones produced both T-LPF and B-LPF. B-LPF stimulate the polyclonal differentiation of Ig+ B cells into PFC without the apparent need for helper T cells, is different from T-LPF, and induces almost exclusively IgM PFC. The B-LPF described in the present paper are compared with previously described T-cell factors, which stimulate antigen-specific B-cell responses or bystander B-cell responses. The conclusion is that B-LPF are probably different from B-cell growth factors, T-cell replacing factors, allogeneic effector factors, and interleukin 2.
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002454:Cell Differentiation; D002460:Cell Line; D002874:Chromosome Mapping; D002999:Clone Cells; D004912:Erythrocytes / Q000502:physiology; D005796:Genes; D006183:H-2 Antigens / Q000235:genetics; D006462:Hemolytic Plaque Technique; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D012756:Sheep / Q000276:immunology; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D006183:H-2 Antigens; D000949:Histocompatibility Antigens Class II