FALURE OF RECOMBINATION ACTIVATING GENE EXPRESSION OF ANATI-DNA AUTOANTIBODY SECRETING B LYMPHOCYTES IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Normal mature B lymphocytes have recently been shown to reexpress RAG proteins.The studies suggest a role of RAG reexpressed in mature B cells for their changing Ag receptor specificity in the further maturational process of mature B lymphocytes。Here，we have characterized RAG expression of mature B lymphocytes。Normal peripheral blood B cells did not express RAG proteins spontaneously.Activation by SAC+IL-2and anti-CD40+IL-4，IL-7，or IL-10 induced cytoplasmic expression of RAGs.Nuclear translocation and recombination signal sequence binding activity of the RAG complex were verified by Western blotting and a gel shift assay。Usage of a downstream J I D2k I D2was evident in B cells having expressed RAG complex.Λlight chain and intracellular RAGs were simultaneously expressed on the purified k+B cells after activation with SAC+IL-2for3-4days，suggesting rearrangement of light chain gene in normal human mature B cells.Some of RAG expressing B cells，which may have resulted in unsuccessful secondary rearrangement died via apoptosis，evidenced by annexin V binding。If autoreactive B cells express RAGs appropriately，they would revise their surface immunoglobulin or would die，leading to elimination of the autoreactive B cells.We found that anti-DNA auto Ab secreting B cells did not express RAG at all，and thus the B cells secreting anti-DNA did not revise their lg gene nor die via apoptosis，allowing development and persistence of autoAb secretion in SLE patients。These results suggest that failure of RAG reexpression in anti-DNA secreting B lymphocytes may be important for the auotAb secretion of SLE patients。

Normal mature B lymphocytes have recently been shown to reexpress RAG proteins. The studies suggest a role of RAG reexpressed in mature B cells for their changing Ag receptor specificity in the further maturational process of mature B lymphocytes. Here, we have characterized RAG expression of mature B lymphocytes. Normal peripheral blood B cells did not express RAG proteins spontaneously. Activation by SAC+IL-2 and anti-CD40+IL-4, IL-7, or IL-10 induced cytoplasmic expression of RAGs. Nuclear translocation and recombination signal sequence binding activity of the RAG complex were verified by Western blotting and a gel shift assay. Usage of a downstream JィイD2kィエD2 was evident in B cells having expressed RAG complex. Λ light chain and intracellular RAGs were simultaneously expressed on the purified k+B cells after activation with SAC+IL-2 for 3-4 days, suggesting rearrangement of light chain gene in normal human mature B cells. Some of RAG expressing B cells, which may have resulted in unsuccessful secondary rearrangement died via apoptosis, evidenced by annexin V binding. If autoreactive B cells express RAGs appropriately, they would revise their surface immunoglobulin or would die, leading to elimination of the autoreactive B cells. We found that anti-DNA auto Ab secreting B cells did not express RAG at all, and thus the B cells secreting anti-DNA did not revise their lg gene nor die via apoptosis, allowing development and persistence of autoAb secretion in SLE patients. These results suggest that failure of RAG reexpression in anti-DNA secreting B lymphocytes may be important for the auotAb secretion of SLE patients.