title: B-cell precursors specific to sheep erythrocytes. Estimation of frequency in a specific helper assay.
abstract: A sensitive, specific, and reproducible in vitro helper assay is described which is suited to limiting dilution analysis of murine B cells. 1 in about 3,000 syngeneic splenic B cells can be induced to form plaque-forming cells (PFC) to sheep erythrocytes in this system. The induction of PFC is absolutely dependent on antigen  and specific helper T cells.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004306:Dose-Response Relationship, Immunologic; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D008211:Lymphocyte Cooperation; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D012756:Sheep; D013601:T-Lymphocytes / Q000276:immunology