Immune responses to the protein, carbohydrate and lipid antigens of Nocardia asteroides in experimental nocardiosis in mice.

The intravenous injection of Nocardia asteroides into mice produced systemic nocardiosis involving all the vital organs. Infection of the kidneys and adrenals was more persistent and progressive than in other organs as evidenced by increased bacterial counts and histopathological findings. During the course of the experimental infection, no humoral immune response was detected against various protein antigens up to 4 weeks after challenge, but significant cell-mediated immunity (CMI) was found. Phospholipid antigens elicited only a humoral immune response. The increased CMI responses with protein antigens correlated well with the decreasing bacterial load, which suggested that CMI against proteins was important in the pathogenesis of this disease.