The proliferation rate of T and B lymphocytes in cerebrospinal fluid.

An immunocytochemical method is presented by which individual proliferating T and B lymphocytes can be detected in the cerebrospinal fluid (CSF) of patients with inflammatory and neoplastic diseases of the central nervous system. The absolute numbers of proliferating T and B lymphocytes were approximately equal, so that only a minority of the strongly prevailing T-cell population proliferates in the CSF during the immune process. The highest proliferation (25.7%) was found within the small subset of activated, i.e. cytoplasmic immunoglobulin-containing, B lymphocytes. This provides further evidence that these cells are not the terminally differentiated plasma cells of classical cytology but progenitor cells capable of further proliferation. B-cell lymphomas could be easily identified. The detection of abnormally proliferating cell subsets could help in the differentiation of opportunistic infection from leukaemic infiltration.