Immunity to Cholera: The Occurrence and Nature of Antibody-Active Immunoglobulins in the Lower Ileum of the Rabbit

Abstract

Earlier studies suggested that immunity to direct challenge with cell-free cholera toxin in the rabbit ileal loop model may be associated with tissue-contained antibody as reflected in serum antitoxin titers, and showed that extracts of epithelium from the lower ileum of immunized rabbits contained relatively large amounts of such antibody. In this study the intestinal epithelium from rabbits immunized by the intraperitoneal or intra-intestinal routes was separated into crypt and villus cell fractions by a modification of the method of Harrison and Webster. The toxin-neutralizing antibody of ultrasonic lysates of such cells was primarily in the crypt cells, while villus cells contained only small amounts of antibody activity later in the immune response. The titration of the antibody activity of immunoglobulins separated on DEAE cellulose and Sepharose 6B from tissue extracts showed that IgG had both vibriocidal and antitoxic activity, and 11S IgA only antitoxic activity. The intracellular antibody appeared to be predominantly, or exclusively, IgA.