Chronic granulomatous disease is an inherited disorder associated with a defect in phagocytic cell oxidative metabolism resulting in ineffective microbicidal activity. Consequently, patients with chronic granulomatous disease suffer from recurrent infections. Published data show that besides the failure to produce superoxide and its derivatives, other functional problems can also be found in chronic granulomatous disease-mutant cells. Since in innate immune responses other mediators, such as cytokines, also play an important role, we hypothesized that there may be a disturbance in cytokine production by chronic granulomatous disease-mutant cells as well. To prove this hypothesis, the production of tumour necrosis factor-alpha, an important proinflammatory cytokine, was determined by enzyme-linked immunosorbent assay in wild-type and chronic granulomatous disease-mutant myelomonoblastic PLB-985 cells in their immature, granulocytic and monocytic/macrophage differentiated forms. Tumour necrosis factor-alpha production was induced with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (100 nmol/L), lipopolysaccharide (10 micro g/mL), opsonized zymosan (100 micro g/mL) or phorbol 12-myristate 13-acetate (100 nmol/L) for 24 h. We could demonstrate that: (i) there were marked differences in tumour necrosis factor-alpha production only in the differentiated forms of both wild-type and chronic granulomatous disease-mutant cells, while there were no differences in the case of their immature counterparts; (ii) only chronic granulomatous disease-mutant cells retained sensitivity to phorbol 12-myristate 13-acetate both in their granulocytic and monocytic forms, although phorbol 12-myristate 13-acetate responsiveness was a characteristic of both types of immature cells; (iii) the granulocytic form of wild-type cells produced tumour necrosis factor-alpha after opsonized zymosan stimulation, but such a response was not observed in cells originating from the chronic granulomatous disease-mutant cell line; (iv) with the monocytic forms, significantly higher tumour necrosis factor-alpha production could be induced by lipopolysaccharide in the wild-type cells than in the chronic granulomatous disease-mutant cells, although there was no difference in their lipopolysaccharide receptor CD14 expression. In summary, these data show an altered inducibility of tumour necrosis factor-alpha production by chronic granulomatous disease-mutant cells. Our observations suggest a further defect in differentiated chronic granulomatous disease-mutant cells in addition to the known defect in reduced nicotinamide adenine dinucleotide phosphate oxidase, which may contribute to the development of susceptibility to infections in people with chronic granulomatous disease.