[Lymphocyte in chronic lymphatic leukemia]

In patients with chronic lymphatic leukemia (CLL) the majority of peripheral blood lymphocytes was characterized as B cells by surface membrane markers. Ultrastructural studies revealed a reduction of the cytoplasmic area. Furthermore, the number of lysosomes was diminished corresponding to a decreased activity of lysosomal hydrolases. Increasing blood lymphocytosis was paralleled by an increase of the percentage of lysosome-poor lymphocytes. Response of CLL lymphocytes to in vitro stimulation with PHA and PWM was either lacking or diminished and/or delayed, and the number of transformed cells was reduced. Thus, the majority of CLL lymphocytes appears to represent both morphologically and functionally abnormal neoplastic b cells. During the early and later phase of stimulation the mitogen-reactive CLL lymphocytes exhibited alterations of the lysosomal apparatus similar to those observed in normal cells. The reactive lymphocytes may be derived from residual populations of normally functioning T and/or B cells. However, the neoplastic cells may also be able to respond to the mitogens. In vivo studies showed impaired kinetics of circulation and recirculation of CLL B lymphocytes, whereas the T cells were normal in this respect.