Antibacterial functions of macrophages in experimental protein-calorie malnutrition. I. Description of the model, morphologic observations, and macrophage surface IgG receptors.

An experimental protein-calorie malnutrition was produced in weanling Sprague-Dawley rats. The model resembles human malnutrition with respect to weight loss, inanition, angular stomatitis, anemia, lymphopenia, hypoproteinemia with hypoalbuminemia, and marked thymic involution. In addition, systemic invasion by gram-negative rods was documented. However, no edema was produced, and animals did not survive for longer than six weeks on the protein-deficient diet. One percent glycogen was found to be a satisfactory nonprotein stimulus for induction of a peritoneal exudate consisting primarily of young macrophages. Electron microscopy showed that morphologic events of phagocytosis and degranulation proceeded normally in macrophages from protein-deficient animals. In addition, cell surface receptors for IgG were preserved under these experimental conditions. These data indicate that weanling rats may be employed as a small animal model for servere, fulminant protein-calorie malnutrition in humans.