Functional analysis of chronic T lymphocytosis with peculiar phenotype

Abstract

The lymphocytes obtained from a patient with chronic T-cell lymphocytosis were analyzed. The patient has no clinical symptoms or sings during our 8-year observation. The lymphocytes showed the typical feature of large granular lymphocytes (LGLs) morphologically. They had peculiar phenotype different from that of LGLs previously reported. The surface markers of these lymphocytes were CD2+, CD3+, CD4+, CD5+, CD8-, CD11+, Leu7+, CD16- and FcIgG-, but these cells had neither helper nor suppressor action on IgG production by normal B lymphocytes. Natural killer activity of freshly isolated cells could not be detected even after augmentation with interleukin 2 (IL2). Lymphokine activated killer activity could not be detected, either. These cells were able to proliferate upon stimulation with such mitogens as PHA and PWM, and to produce IL2. But they were not induced to proliferate by IL2 even if stimulated with ConA beforehand. Almost all cells were in the resting state according to the cell cycle analysis. The LGLs of this case are a novel subset of LGLs in both phenotype and immunological function. Only a few cases of CD4+ LGL lymphocytosis or leukemia have been reported previously, but the further phenotype and the function of these cases varied. The results show that, even in CD4+ LGLs, there may be heterogeneous subpopulation.