Differences in blood T and NK cell populations between chronic lymphocytic leukemia of B cell type (B-CLL) and monoclonal B-lymphocytosis of undetermined significance (B-MLUS).

T and NK cell blood subpopulations were determined in 33 patients with B-CLL and in 14 patients with B-MLUS by two-color immunofluorescence. CLL patients had significantly higher total numbers of Leu-7+ and CD8+ cells and lower numbers of CD16+/Leu-7- cells as well as a higher Leu-7/CD16 ratio and a lower CD4/CD8 ratio than MLUS patients and control donors. Moreover, MLUS patients exhibited a significantly lower Leu-7/CD16 ratio as well as a higher frequency of CD16+/Leu-7- cells than healthy donors. These results suggest that B-CLL patients have higher numbers of circulating immature NK cells compared to B-MLUS, while B-MLUS patients have a larger proportion of NK cells with a high lytic capability as compared to both CLL and normal controls. The imbalance between CD4+ and CD8+ cells was prominent in CLL with a low CD4/CD8 ratio, but within the upper normal range in MLUS. Differences in immunoregulatory cell subpopulations between B-CLL and B-MLUS might therefore contribute to the different clinical behavior of these two disorders.