Lymphocyte abnormalities in preleukemia--I. Decreased NK activity, anomalous immunoregulatory cell subsets and deficient EBV receptors.

The development of acute non-lymphocytic leukemia is preceded by a set of symptoms described as the preleukemia syndrome. Six patients who fulfilled the criteria for this preleukemia syndrome have been evaluated for abnormalities in the lymphocyte population. The NK cell activity was reduced, the immunoregulatory cell populations were numerically abnormal, and the B cell subpopulation was deficient in EBV receptors. Thus, in addition to the abnormalities in the myeloid populations, there are serious defects in the lymphoid systems of preleukemic patients.