We describe a 15-yr-old girl with recurrent bacterial infections who is refractory to the effects of LPS in vivo and in vitro and IL-1 in vitro. Intravenous challenge of the patient with Escherichia coli endotoxin caused a subnormal febrile response, little alteration in the number of circulating neutrophils, and subnormal elevations in the plasma levels of TNF-alpha, IL-6, IL-8, lactoferrin, and granulocyte CSF; however, normal levels of the anti-inflammatory mediators IL-1 receptor antagonist and soluble TNF receptor (60 kDa) were induced. Studies in vitro indicated the patient's monocytes expressed CD14, the LPS receptor, and bound LPS in a specific manner, but failed to produce TNF-alpha and granulocyte CSF after stimulation with LPS, and failed to respond to IL-1, heat-killed Staphylococcus aureus, and soluble glucan. Peripheral blood patient neutrophils exhibited normal expression of CD14, but failed to respond to treatment with LPS (100-1000 ng/ml for 30 min at 37 degrees C), a treatment that caused increased expression of the surface markers, C10, CD18, CD11b, CD67, and CD45, and decreased expression of L-selectin in normal neutrophils. Treatment of normal and patient neutrophils with FMLP (0.1 microM) resulted in equivalent altered expression of these surface markers. Patient neutrophils could not be primed by either LPS or IL-1beta for enhanced FMLP-induced O2- generation, but primed normally to TNF-alpha and platelet-activating factor. This patient's hyporesponsiveness to LPS and IL-1 is most likely due to a defect very early in the signal-transduction pathway.