title: Antigen-initiated B lymphocyte differentiation: non-specific stimulation changes the physical properties of virgin AFC-progenitors in neonatal mouse spleen.
abstract: While the virgin AFC-progenitors for an adoptive immune response in neonatal germ-free CBA mouse spleen are small, dense cells, the equivalent cells in the adult are a larger, lighter density population. The effects of injections of unrelated antigens on the physical properties of the AFC-progenitors in neonatal spleen were investigated to test the postulate that the physically distinct "virgin" AFC-progenitors in the adult arose by a process of non-specific activation. Spleen cells from 7-day-old germ-free CBA mice were separated by sedimentation at unit gravity or by density on continuous albumin gradients, and the fractions were tested for NIP-specific AFC-progenitor activity using an adoptive immune assay which gave a direct linear measure of B cell activity. If the donor neonatal animals were injected one day previously with POL or PPD, the NIP-specific AFC-progenitor activity shifted from the typical small, dense lymphocytes to larger, lighter cells. The physical properties of these stimulated AFC-progenitors resembled those of IgM AFC-progenitors in normal adult mice. These results experimentally confirm the theory that environmental stimuli induce a non-specific "activation" of a particular subset of "virgin" B cells.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D000942:Antigens, Bacterial; D001402:B-Lymphocytes / Q000276:immunology*; D002469:Cell Separation; D002499:Centrifugation, Density Gradient; D005856:Germ-Free Life; D007075:Immunoglobulin M / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000166:cytology; D051379:Mice; D013154:Spleen / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D007075:Immunoglobulin M