Activation of mouse lymphocytes by anti-immunoglobulin. II. A thymus-independent response by a mature subset of B lymphocytes.
Mouse spleen cells can be stimulated to proliferate in vitro by purified anti-mu or anti-gamma,kappa antibodies. These responses can be obtained in cell populations bearing  membrane immunoglobulin (Ig), purified by the fluorescence activated cell sorter (FACS), but they are not observed in FACS-purified Ig- cell populations. Furthermore, treatment of spleen cell populations with anti-Thy 1.2 and complement does not impair the response, nor does addition of nylon wool-purified T lymphocytes enhance it. These results indicate that B lymphocytes respond to anti-Ig and that their response does not require T cells. On the other hand, cells from athymic nude (nu/nu) mice respond slightly less well to anti-mu than do cells from heterozygous littermate (nu/+) controls; nu/nu cells are almost unresponsive to anti-gamm,kappa and addition of nylon wool-purified T cells from nu/+ controls does not restore the response. This suggests that T lymphocytes or the thymus may control the appearance of cells responsive to anti-gamma,kappa. Responsiveness of normal mice to anti-mu does not appear until 4 wk of age and does not reach maximum levels until 8 wk of age. Acquisition of full responsiveness to anti-gamma,kappa is even more delayed. This, together with the failure of mice with the CBA/N B-cell defect to respond to anti-Ig, suggests that cells stimulated to proliferate by anti-Ig are a mature subset of B cells. Depletion of adherent cells by Sephadex G-10 treatment or by treatment with carbonyl iron and exposure to a magnetic field does not diminish anti-mu or anti-gamma,kappa responses, suggesting that the responsiveness does not require the presence of macrophages. Thus, activation of B-cell proliferation by anti-Ig appears to be a T-cell independent, macrophage-independent process in which membrane Ig plays a direct role in signal generation.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D007142:Immunoglobulin gamma-Chains; D007148:Immunoglobulin mu-Chains; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008221:Lymphoid Tissue / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D051379:Mice; D011947:Receptors, Antigen, B-Cell; D013601:T-Lymphocytes / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D007142:Immunoglobulin gamma-Chains; D007148:Immunoglobulin mu-Chains; D011947:Receptors, Antigen, B-Cell