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. Tγ and Tμ, in chronic lymphocytic leukemia (CLL) patients. Serial evaluations of the numbers of Tγ and Tμ subsets in CLL were performed in order to delineate more completely the patterns of T cell abnormalities. Two groups of CLL patients were studied: (1) previously untreated (n = 3) and (II) stable CLL on chemotherapy (n = 12). In Group I, two of three patients had significantly increased percentages of Tγ cells (mean ± S.E.M. = 57 ± 5 vs 18 ± 2 for controls). There was defective in vitro appearance of Tμ cells in both groups. In Group II, repeated studies of T cell subsets revealed persistently elevated Tγ cells despite various modes of oral chemotherapy. In three CLL patients who required splenectomy a dramatic decrease in the percentages of Tγ, 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 Tγ cells in stable patients and (3) removal of infiltrated CLL spleens results in a dramatic decrease in the proportion of Tγ cells. This latter finding plus the increase in Tγ cells in progressive disease post-splenectomy suggest Tγ cells may be an important determinant of the course of CLL.