Activation of T and B lymphocytes in NZB mice.

Since NZB mice manifest evidence of intense B cell activation, the state of activation of their T cells was explored. Electron microscopic examination and automated laser light scatter analysis demonstrated the presence of many blast lymphocytes in the spleens of aging NZB mice but not in controls. Only 45% of these large cells were B cells by the criterion of stainable surface IgM. NZB T and B cells were separated using the fluorescence-activated cell sorter; cytographic analysis revealed that both T and B cell populations contained substantial numbers of blast cells. The data thus indicated that T cells, as well as B cells, undergo activation as autoimmunity develops in NZB mice.