Neutrophil response, serum opsonic activity, and precipitating antibodies in human infection with Actinobacillus hominis.

Actinobacillus species are usually not considered as being human pathogens apart from A. actinomycetemcomitans. However, single cases of human meningitis, septicemia, and empyema caused by Actinobacillus lignieresii have been reported in the literature. This is the first reported case of Actinobacillus hominis giving rise to pleural-empyema in a patient with carcinoma of the lung. The function of peripheral blood neutrophils, serum opsonic activity and specific precipitating antibodies were investigated. Neutrophils from the patient exhibited an enhanced oxidative burst response measured by chemiluminescence assay. Furthermore, the opsonic activity of the serum from the patient was higher than that of a healthy control person. Several precipitating antibodies to various antigens of Actinobacillus hominis were demonstrated in the serum of the patient by crossed immunoelectrophoresis.