Local immunization in the mammary glands of the rabbit

The effects of a local immunization with bovine serum albumin in the left mammary glands of the rabbit have been compared with those of an intramuscular (i.m.) immunization. The ability of several tissues to synthesize antibodies was studied in vitro with or without in vitro antigenic stimulation, and the antibody class in the plasmocytes of these tissues was determined by immunofluorescence. After i.m. immunization, the serum antibodies synthesized by the spleen and the lymph nodes pass into the milk by transudation; there is no antibody synthesis in the mammary glands. After immunization in the left mammary glands, there is antibody synthesis in the left mammary glands and also in the spleen and lymph nodes. In the mammary glands in the antibodies belong essentially to the IgG class and are synthesized by the plasmocytes that infiltrate the granulation tissue around the injection sites. The fragments of the immunized glands are capable of an in vitro secondary response analogous to that made by the spleen and lymph nodes. Thus the local immunization of the mammary glands does not stimulate the secretory immunologic system but elicits an antibody synthesis in the granuloma as in any other tissue. This local immunization also provokes a traffic of sensitized cells to the same lymphoid tissues as an i.m. immunization does.