Lymphocytopenia preceding chronic lymphocytic leukemia.

In 11 patients with an average peripheral blood lymphocyte count of 21.1 x 109/l at the time of diagnosis of chronic lymphocytic leukemia (CLL), WBC and differential counts had been recorded on 1-26 occasions more than 5 years before the diagnosis. The median lymphocyte count in the preleukemic period was 1.3 x 109/l found in a sex- and age-matched control series. In 3 patients lymphocytopenia coexisted with normal levels of serum immunoglobulins in the preleukemic period. It is suggested that the preleukemic lymphocytopenia was mainly due to low numbers of T-cell and that a deficiency in T-lymphocytes may favour the development of the malignant, monoclonal B-cell proliferation characteristic of CLL.