Interleukin-4 augments the cytotoxic capacity of lymphocytes and monocytes in antibody-dependent cellular cytotoxicity.

Human peripheral blood mononuclear cells (lymphocytes and monocytes) (PBMC) were preincubated for 0-24 h with human recombinant interleukin-4 (IL-4) and used as effector cells in an 18 h antibody-dependent cellular cytotoxicity (ADCC) assay with mAb 17-1A (mouse IgG2A) against SW948 (a human colorectal carcinoma cell line). A statistically significant increase in the lytic capability was noted after 2-24 h of preactivation. IL-4 at 1 ng/ml induced the highest cell lysis while higher and lower concentrations were inferior or had no effect at all. Preactivation for 24 h induced a more effective lytic cell population than 2 h prestimulation: 63 LU (lytic units)/10(6) cells vs 42 LU/10(6) cells. Pretreatment with 1 ng/ml IL-4 for 2 h induced a statistically significant increase in the ADCC activity of PBMC (P less than 0.05), of monocytes (P less than 0.01) and E-rosette-negative cells (natural killer cells) (P less than 0.05) compared to non-activated cells. IL-4 did not induce lymphokine-activated killer activity of PBMC against SW948. The spontaneous cytotoxicity against K562 was, however, increased after stimulation with 1 ng/ml IL-4 for 2 h of E-rosette-negative non-adherent cells.