Effect of therapy on T cell subpopulations in patients with chronic lymphocytic leukemia.

We have previously demonstrated functional and quantitative imbalances in two human thymic (T) cell subpopulations, T gamma and T mu, in chronic lymphocytic leukemia (CLL) patients. Serial evaluations of the numbers of T gamma and T mu subsets in CLL were performed in order to delineate more completely the patterns of T cell abnormalities two groups of CLL patients were studied: (I) previously untreated (n = 3) and (II) stable CLL on chemotherapy (n = 12). In Group I, two of three patients had significantly increased percentages of T gamma cells (mean +/- S.E.M. = 57 +/- 5 vs 18 +/- 2 for controls). There was defective in vitro appearance of T mu cells in both groups. In Group II, repeated studies of T cell subsets revealed persistently elevated T gamma cells despite various modes of oral chemotherapy. In three CLL patients who required splenectomy a dramatic decrease in the percentages of T gamma cells was noted post-splenectomy (51 +/- 3 to 15 +/- 3). In all cases the spleen was diffusely involved with CLL. These findings indicate: (1) abnormalities of T cell subsets are present early in CLL, (2) chemotherapy does not affect the levels of T gamma cells in stable patients and (3) removal of infiltrated CLL spleens results in a dramatic decrease in the proportion of T gamma cells. This latter finding plus the increase in T gamma cells in progressive disease post-splenectomy suggest T gamma cells may be an important determinant of the course of CLL.