Clinical signification of natural killer activity in B‐cell chronic lymphocytic leukemia

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Abstract
The natural killer (NK) activity of peripheral blood mononuclear cells (PBMC) and lymphocytes with the capacity to form stable rosettes with neuraminidase-treated sheep red blood cells (E-) was studied in 28 previously untreated patients (11 at stage 0, 10 at stage 1 and 7 at stages II and III, according to Rai''s classification) and 7 treated patients with B-cell chronic lymphocytic leukemia (B-CLL), all of them at stage 0 according to Rai''s classification after treatment, and in 15 healthy controls. The mean NK activities of PBMC and E+ lymphocytes from untreated patients were significantly decreased (p < 0.001) when compared with those of PBMC and E+ lymphocytes, respectively, from healthy controls. However, PBMC and E- cells from treated patients demonstrated NK activity similar to that of the corresponding cellular populations of controls (p > 0.05). Furthermore, there were no significant differences among the NK activities of E+ lymphocytes from untreated B-CLL patients in the different clinical stages 0, I, II and III, according to Rai''s classification (p > 0.05). These results demonstrate that the very low or undetectable levels of NK activity present in PBMC and E+ cell populations from previously untreated patients with B-CLL, regardless of the clinical stage of the disease, can be modified by systemic therapy with alkylating agents. Moreover, the NK activity of PBMC and E+ lymphocytes from some treated patients that have achieved the stage 0 according to Rai''s classification after chemotherapy can be found within the range of the lytic activity shown by PBMC and E+ cells from normal donors.