RESUMO
The importance of specific immune response, and a means of enhancing specific protection against leprotic infections, have been investigated. Rats were challenged with M. leprae murium after having received the following antigens: attenuated tubercle bacilli of the BCG and R1Rv strains, heat-killed suspensions of M. leprae murium, and the attenuated tubercle bacilli accompanied by smaller amounts of M. leprae murium antigen. The results indicate that specific antigen plays a distinctive role in protection and that superior protection is afforded by small amounts of specific antigen combined with the tubercle bacilli as stimulators of immune response. Significant protection was achieved by single administrations of antigen, on a basis adopted to practical application. The liabilities which may attend large and repeated doses of mycobacterial antigens have been emphasized as peculiar to those individuals most in need of protection. The theoretical basis of enhancing response to modest amounts od specific antigen has been indicated.