title: Effects of antigens and lymphokines on early activation of single hapten-specific B lymphocytes.
abstract: An assay was developed to monitor early activation of single fluorescein-specific B cells obtained from the spleens of nonimmunized adult mice by prefractionation on hapten gelatin. Early activation was assessed as a significant increase in the diameter of individual B cells after 24 hr in vitro. Significant enlargement of the single B cells was induced within 24 hr by either T-independent antigens acting alone or a crude source of B cell growth and differentiation factors (EL-BGDF-pik) acting alone. In contrast, T-dependent antigens acting alone were ineffective. When selected T-independent antigens and EL-BGDF-pik acted together, a greater number of B cells were induced to enlarge. B cell stimulatory factor 1 (BSF 1) behaved in a similar manner as EL-BGDF-pik, inducing early B cell enlargement both in the absence and more so in the presence of antigen. Both EL-BGDF-pik and BSF 1 enhanced the survival of single hapten-specific B cells during the 24-hr period. Interleukin 1 was unable to cause B cell enlargement when acting alone, although it was able to augment B cell enlargement induced by antigen. Interleukin 2 did not induce cell enlargement in either the presence or absence of antigen. Activation was demonstrated among cells of all sizes, regardless of the stimulus, although a greater response was demonstrated amongst the larger cell population. The addition of 3T3 filler cells enhanced early B cell activation and cell survival during the 24-hr period. The 24-hr B cell enlargement assay as applied to isolated single cells provides an unequivocal approach to the analysis of early B cell activation, adding a further parameter for the dissection of the precise roles of antigen and the various factors in the B cell differentiation pathway.
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D002458:Cell Fractionation; D019793:Fluorescein; D005452:Fluoresceins; D006133:Growth Substances / Q000494:pharmacology; D006241:Haptens / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4; D008213:Lymphocyte Activation / Q000187:drug effects; D008222:Lymphokines / Q000494:pharmacology*; D051379:Mice; D008808:Mice, Inbred CBA / Q000276:immunology
chemical_list: D000941:Antigens; D005452:Fluoresceins; D006133:Growth Substances; D006241:Haptens; D007376:Interleukin-2; D008222:Lymphokines; D015847:Interleukin-4; D019793:Fluorescein