title: In vitro regulation of IgA subclass production. III. Selective transformation of IgA1 producing cells by Epstein-Barr virus.
abstract: In past experiments, using limited dilution analysis, we have demonstrated that a high percentage of immunoglobulin-secreting clones derived from Epstein-Barr virus- (EBV) stimulated lymphocytes secrete IgA. To further characterize the IgA produced by these clones, the IgA subclass of supernatants from clones stimulated 4 to 6 wk previously with EBV was determined by radioimmunoassay. All of 17 IgA-producing clones secreted IgA1; none secreted IgA2. Because we have shown that surface IgM+ (sIgM+) B cells are an enriched source of IgA2 plasma cell precursors, panning techniques were used to purify sIgM+ B cells from tonsils. Of 103 clones derived from these sIgM+ B cells, 102 secreted IgA1 and only one secreted IgA2. The relative absence of IgA2-producing clones could not be attributed to an absence of EBV receptors on IgA2 cells. A mean of 84 +/- 4% of freshly isolated IgA2 B cells and 78 +/- 6% of IgA1 B cells could be stained with a monoclonal antibody binding the EBV receptor; and there was no failure of EBV to infect IgA2 plasma cells precursors. Of IgA2 plasma cells derived from peripheral blood lymphocytes stimulated 7 days previously with EBV, 54 +/- 7% were positive for the EBV nuclear antigen, compared with 54 +/- 18% of IgA1 plasma cells from the same cultures. Seven days after EBV stimulation, a mean of 25% of the total IgA plasma cells were positive for cytoplasmic IgA2, whereas by 21 days after stimulation only 7% were positive for IgA2. This shift in the proportions of IgA1 and IgA2 plasma cells could be attributed to a failure of the IgA2 plasma cell number to increase after 10 days in culture. There was no evidence for selective suppression of IgA2 production by T cells or selective lysis of IgA2 plasma cells by infectious EBV particles. These results demonstrate that although precursors for both IgA1- and IgA2-producing cells can be stimulated to differentiate in response to EBV, there is preferential transformation of IgA1-producing cells.
mesh_terms: D000921:Antibody-Producing Cells / Q000145:classification / Q000382:microbiology*; D001402:B-Lymphocytes / Q000145:classification / Q000276:immunology* / Q000382:microbiology; D002472:Cell Transformation, Viral; D004854:Herpesvirus 4, Human; D007070:Immunoglobulin A / Q000096:biosynthesis*; D007075:Immunoglobulin M / Q000032:analysis; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D011991:Receptors, Virus / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D011991:Receptors, Virus