Recombinant human interferon gamma enhances neutrophil respiratory burst and bactericidal activity in patients with chronic granulomatous disease. Mononuclear leukocytes of patients with the hyperimmunoglobulinemia E syndrome (Job syndrome) produce low or undetectable levels of this lymphokine. For these reasons we have restudied neutrophil chemotaxis in a group of our patients with the syndrome and determined the effect of recombinant human interferon gamma on the responses. Each of the patients had neutrophil chemotactic responses ranging from 22% to 55% of simultaneous control values (p less than 0.001). After incubation with interferon gamma, a significant improvement in chemotactic responsiveness was observed in the neutrophils of each of the patients (mean 301% of baseline chemotaxis; p less than 0.008). These data suggest the need for a double-blind, placebo-controlled trial of interferon gamma in a larger group of patients with the syndrome of hyperimmunoglobulinemia E and recurrent infections.