title: Differential radiosensitivity among B cell subpopulations.
abstract: We have previously shown that low doses of ionizing radiation selectively impair a functionally defined B cell subpopulation. Normal mice, after exposure to 200 rad of ionizing radiation, have normal or near normal splenic plaque-forming cell responses to thymus-independent type 1 Ag, but reduced responses to thymus-independent type 2 Ag. Here, we confirm and extend the original findings by using hapten-specific serum RIA to demonstrate this differential radiosensitivity is systemic. We also examined splenocytes stained with a panel of lymphocyte surface Ag by FACS analysis to determine if these functional changes are accompanied by a physical alteration of the B cell pool of irradiated mice. Single-parameter FACS analyses demonstrate a diminution in both B cell number and the heterogeneity of membrane Ag expression within the surviving B cell pool after irradiation. In contrast, T cells are relatively radioresistant as the relative percentage of T cells in the irradiated splenocyte pool increases, whereas the heterogeneity of membrane Ag expression remains constant. Multiparameter FACS analyses indicate that B cells with the sIgM much greater than sIgD phenotype are more radiosensitive than B cells of the sIgM much less than sIgD phenotype. In addition, immunohistochemical analysis of splenic sections stained with anti-IgM or anti-IgD reveal the enhanced radiosensitivity of marginal zone B cells.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000145:classification / Q000276:immunology / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006462:Hemolytic Plaque Technique; D007072:Immunoglobulin D / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007150:Immunohistochemistry; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D010641:Phenotype; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D013154:Spleen / Q000033:anatomy & histology / Q000166:cytology* / Q000528:radiation effects
chemical_list: D007072:Immunoglobulin D; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell