title: Effect of vinblastine on the early events in the humoral immune response of mice to SRBC.
abstract: The effect of vinblastine (VLB), a mitotic blocking agent, on the number of plaque-forming cells (PFC) and on the metabolic activities of spleen cells of mice reimmunized with SRBC was studied. When VLB (75 mug/mouse) and antigen were administered simultaneously, the number of pfc, on the 4th day after immunization, was reduced to 40% of control levels. However, when the same amount of VLB was administered to mice 24 h after immunization, it reduced the number of PFC to 10% of control levels. The possibility that VLB exerts a specific cytotoxic effect on preformed PFC either in vivo or in vitro was ruled out. A direct profound effect of VLB on antigen-stimulated cells was observed when VLB was injected 24 h after reimmunization, and the incorporation rates of radioactive precursors into macromolecules by spleen cells were measured at 4-hour intervals. VLB suppressed completely the antigen-induced peak of 3H-thymiding incorporation, while it had no effect on the incorporation rate of 3H-uridine and only a slight effect on the incorporation rate of 3H-amino-acids by the same cells. The results suggest that the decrease in number of PFC caused by injection of VLB 24 h after immunization is due to prevention by VLB, of precursor cells from going through a critical cell division, which takes place later than 24 h after immunization. Thus, at least one cell division is required for an immune response in vivo.
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D000921:Antibody-Producing Cells / Q000187:drug effects*; D000941:Antigens; D004912:Erythrocytes / Q000276:immunology; D006462:Hemolytic Plaque Technique; D051379:Mice; D008810:Mice, Inbred C57BL / Q000276:immunology; D012756:Sheep / Q000276:immunology; D013154:Spleen / Q000276:immunology; D014747:Vinblastine / Q000494:pharmacology*
chemical_list: D000941:Antigens; D014747:Vinblastine