Intestinal plasmacytosis in rabbits: a histologic and ultrastructural study

A retrospective study revealed intestinal plasmacytosis in 53 of 102 rabbits used in various experimental studies and as controls. The breeds affected included New Zealand white (n = 46), Dutch-belted (n = 6), and Watanabe (n = 1) rabbits. Sex predisposition was not found in any breed. The mean (+/-SD) ages were 3.1 +/- 1.4 years for New Zealand white rabbits, 1.3 +/- 1.1 for Dutch-belted rabbits, and 2 years for the Watanabe rabbit. The severity increased with animal age. The incidence was higher (P < 0.05) in rabbits used in antibody production and cholesterol studies. The lesions were characterized by multifocal to diffuse infiltration of well-differentiated plasma cells in the intestinal mucosa. Electron microscopic examination revealed typical plasma cell morphology of the infiltrating cells. Small intestine and cecum were the major sites affected. In severe cases, colon, rectum, trachea, esophagus, mesenteric lymph node, and spleen were also involved.