Salmen S, Corte D, Goncalves L, Barboza L, Montes H, Calderón A, Berrueta L. CD40/CD40L expression in leukocytes from chronic granulomatous disease patients. APMIS 2007;115:939–47. Chronic granulomatous disease (CGD) is an inherited disorder caused by defects in the NADPH oxidase complex, which generates superoxide, the precursor of hydrogen peroxide (H2O2) and other reactive oxygen derivatives with microbicidal activity. Because CGD patients are at risk of chronic inflammatory manifestations, including inflammatory bowel disease and autoimmune diseases, and it is not clear whether these pathologies are exclusively secondary to altered superoxide production, or whether distinct immunologic defects are involved, we explored cell proliferation, lymphocyte cell counts, immunoglobulin levels, presence of autoimmune antibodies and expression of costimulatory molecules in leukocytes from CGD patients. We found that CGD patients have a diminished phytohemagglutinin-induced proliferation of blood mononuclear cells. Following stimulation with PMA plus ionomycin, a reduced percentage of CD40L expression in T lymphocytes and a diminished expression of CD40 molecules in neutrophils were observed on leukocytes from these patients. Our results suggest an altered interplay between elements of innate and adaptive immunity in CGD patients, which may be reflected in an increased susceptibility to opportunistic infections.