Animals, Antigens, Surface, Autoimmune Diseases, B-Lymphocytes, Cell Differentiation, Cyclophosphamide, Disease Models, Animal, Female, Gene Expression Regulation, Genetic Linkage, Lupus Erythematosus, Systemic, Lymph Nodes, Lymphatic Diseases, Male, Mice, Mice, Inbred NZB, Mice, Inbred Strains, Mice, Mutant Strains, Models, Biological, Oncogenes, RNA, Messenger, Rodent Diseases, Spleen, T-Lymphocytes, Thymus Gland