Stimulation of T lymphocytes by protein A from Staphylococcus aureus in B-derived chronic lymphocytic leukaemia.

Peripheral blood lymphocytes from five untreated patients affected with B-derived chronic lymphocytic leukaemia were stimulated by protein A from Staphylococcus aureus. A very strong response (with stimulation indexes as high as 182 and percentages of blast cells as high as 90%) was found in all patients. Lymphocyte marker studies showed that the responding cells were T cells. These results and the well known abnormalities of lymphocyte response to other mitogens suggest a disbalance of T lymphocyte subpopulations in B-CLL.