Normal antibody-dependent killer cell function in patients with chronic lymphocytic leukemia.

Area of Science:

• Immunology
• Hematology

Background:

• Chronic lymphocytic leukemia (CLL) is a B-cell malignancy.
• Killer cell activity is crucial for immune surveillance.

Purpose of the Study:

• To investigate the killer cell function in patients with chronic lymphocytic leukemia (CLL).
• To determine if CLL patients have an intrinsic defect in killer cell function or if other factors are involved.

Main Methods:

• Antibody-dependent cell-mediated cytotoxicity (ADCC) assay was used.
• Peripheral blood leukocytes (PBL) from normal individuals and untreated CLL patients were fractionated.
• Nylon wool-nonadherent cells (B-cell-depleted and T- and null-cell enriched) were isolated.

Main Results:

• Unfractionated mononuclear cells from CLL patients showed deficient target cell killing in 5 of 6 patients.
• After removal of adherent cells, killer cell activity in CLL patients was comparable to normal nonadherent cells.
• Killer cell activity was present and enriched in unfractionated normal cells after adherent cell removal.

Conclusions:

• The apparent deficit in killer cell function in unfractionated PBL from CLL patients is due to dilution of effector cells.
• The adherent cell population may contain suppressor cells, or serum factors may suppress killer cell function.
• There is no evidence of an intrinsic defect in killer cell function in CLL patients.