Immunological abnormalities in thalassaemia major. I. A transfusion-related increase in circulating cytoplasmic immunoglobulin-positive cells.

Multiply transfused patients with beta-thalassaemia major have elevated serum immunoglobulin levels and a transfusion-related increase in (T8+) T-suppressor cells. We report here that these patients also have a significantly increased (P less than 0.001) proportion of B-cells that contain cytoplasmic immunoglobulin when visualized immediately upon isolation. On the other hand, the same cell populations do not exhibit an increase in the proportion of immunoglobulin-secreting cells as measured by a reverse haemolytic plaque assay. These results, together with those of ongoing studies, suggest that the cells containing the cytoplasmic immunoglobulin are likely to be terminally differentiated B-cells which persist in the circulation. While the reason for this phenomenon is not yet known, we have found that the increase in these cells is transfusion-related.