ABSTRACT
A study was made of the specific sensitivity to tuberculin in the animals vaccinated with BCG in case of their additional sensitization with various atypical mycobacteria. The mentioned experimental study appeared to be necessary for the purpose of a more proper treatment of the epidemiological date referred to the sensitivity of man to tuberculin and sensitins against the background of mass BCG vaccination. Preliminary BCG vaccination of the animals with their subsequent infection with atypical mycobacteria altered the allergic response to the antigens from the mycobacteria increasing the response reactions not only to tuberculin, but also to sensitins from mycobacteria of the I--III groups by Runyon's classification, closely connected in antigenic respect with mycobacteria tuberculosis. Skin reactions to sensitins from the saprophytic mycobacteria which had in their composition much less common antigens with mycobacteria tuberculosis, remained at the low level. Sensitization with atypical mycobacteria of animals preliminarily vaccinated with BCG failed to cause significant influence on the production of immunity to the subsequent virulent infection with tuberculosis.