Acceptor site(s) for T cell-replacing factor (TRF) on B lymphocytes. II. Activation of B cells by cross-linkage or aggregation of the TRF acceptor molecule.
An in vitro experimental system was established to demonstrate the TRF-substituting activity of an alloantiserum raised in TRF low-responder (DBA2/2Ha x BALB/c)(DC)F, male mice against TRF high-responder parental BALB/c B cells. The TRF substituting activity of the antiserum was apparent in that anti-Thy-1 plus C-treated, DNP-primed B cells from TRF high-responder mice were effectively stimulated, whereas B cells from TRF low-responder DBA/2Ha mice were not, as evidenced by the induction of secondary anti-DNP IgG PFC responses. The specificity of the reaction of the antibody with a component present on the TRF high-responder B cells was also substantiated by the fact that antibody activity was virtually eliminated by absorption with B cells from various TRF high-responder mice but not by TRF low-responder DBA/2Ha B cells. The IgG fraction of antiserum and the F(ab')2 and Fab' fragments of the antibody, which possess a comparable reactivity in regard to the TRF acceptor site(s), were prepared, and analysis of the B cell-triggering mechanism by the antibody was carried out. The results revealed that both the IgG fraction and F(ab')2 fragment, but not the monovalent Fab' fragment, demonstrated effective TRF-substituting activity, indicating that cross-linkage or aggregation of the TRF acceptor site(s) may give rise to differentiation signals to the B cells.
D000818:Animals; D000921:Antibody-Producing Cells / Q000166:cytology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D004136:Dinitrobenzenes / Q000276:immunology; D007106:Immune Sera / Q000494:pharmacology; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007128:Immunoglobulin Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D015848:Interleukin-5; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000378:metabolism* / Q000494:pharmacology; D046911:Macromolecular Substances; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008811:Mice, Inbred DBA; D011947:Receptors, Antigen, B-Cell
D004136:Dinitrobenzenes; D007106:Immune Sera; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments; D007074:Immunoglobulin G; D015848:Interleukin-5; D008222:Lymphokines; D046911:Macromolecular Substances; D011947:Receptors, Antigen, B-Cell