Reduced T lymphocyte colonies in B chronic lymphocytic leukaemia. III. Evidence of a proliferative abnormality of the T helper cell population.

The functional capacity of T and T mu (helper) cells from six untreated cases of B cell chronic lymphocytic leukaemia (B-CLL) was assessed in a double layer T colony forming assay. T lymphocytes from B-CLL originated few T colonies compared with normal T cells (35 +/- 25.9 vs 118 +/- 33.7). After enrichment of the T mu cells, colony growth in B-CLL was still reduced compared with the same cell fraction from normal controls (55 +/- 28.6 vs 90 +/- 35.6). When analysed independently, the three B-CLL cases with the lowest colony forming capacity, after enrichment of the T mu cells showed only a slight increase in growth, still well below the normal range. The two cases with normal or near normal colony growth, gave rise to similar results after T mu enrichment, indicating that, as in normal blood, B-CLL residual T colony formation is a property of the T mu cell population. In only one case was a significant increase and a normalization of the colony growth observed. It is suggested that the functional abnormality of T lymphocytes frequently observed in B-CLL patients, is not due only to the marked imbalance in T cell subsets, with a significant increase in T suppressor/cytotoxic cells and a reduction in T helper/inducer cells, but in many cases to an intrinsic defect of the T mu (helper/inducer) cell population.