G0 B cells activated by anti-mu acquire the ability to proliferate in response to B cell-activating factors independently from entry into G1 phase.
In the present studies we investigated the early steps in B cell activation and determined that activation could be separated from entry into cell cycle. Purified B cells from BALB/c nu/nu mice, activated under controlled conditions by affinity-purified rabbit IgG anti-mu or F(ab')2 fragments prepared from the same antibodies, were sorted according to size by flow cytometry. Approximately 80% of the B cells were small and were shown to be in Go state by quantitative RNA analysis and by [3H]uridine and [3H]thymidine incorporation studies. The sorted Go B cells, when again incubated in serum-free medium with the appropriate anti-mu preparations, remained in Go. However, Go B cells in the presence of anti-mu have undergone significant change(s), in as much as they were now able to proliferate in response to soluble mediators. The ability to develop a proliferative response to B cell-activating factor(s), acquired independently from entry into cell cycle, characterizes another important step in early B cell activation and also indicates that Go B cells characterized on the basis of cell size, density, and/or RNA content may be in an activated state.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000502:physiology*; D001402:B-Lymphocytes / Q000145:classification* / Q000166:cytology / Q000276:immunology; D001688:Biological Products / Q000502:physiology; D002469:Cell Separation; D003470:Culture Media; D016207:Cytokines; D005260:Female; D006133:Growth Substances / Q000502:physiology*; D007140:Immunoglobulin Fab Fragments / Q000502:physiology; D007074:Immunoglobulin G / Q000502:physiology; D007075:Immunoglobulin M / Q000502:physiology*; D015847:Interleukin-4; D007399:Interphase; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude
D000888:Antibodies, Anti-Idiotypic; D001688:Biological Products; D003470:Culture Media; D016207:Cytokines; D006133:Growth Substances; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008222:Lymphokines; C044203:anti-IgM; D015847:Interleukin-4