| Abstract: | Studies with inbred strains of mice revealed that exposure to type 12, Group A, beta-hemolytic streptococci affects the host response to heart grafts implanted in the ear. Intraperitoneal injection of streptococci 10 days before grafting led to curtailed survival of syngrafts without altering the normal rejection time of allografts. Similar sensitization, combined with local injection of streptococci into the graft site at the time of grafting, was followed by rapid rejection of both syngrafts and allografts. The time interval between exposure and grafting was critical. Injection with streptococci 5 days before grafting led to a prolonged survival of allografts and no demonstrable effect on syngrafts. In contrast, injection of streptococci 15 days before grafting did not alter survival of either type of graft. The data indicate heart grafts implanted in the ear may serve as a useful model for the study of the host responses to streptococcal antigens. |
