An analysis of cross reactions among mycobacteria by in vivo and in vitro assays of cellular hypersensitivity.

Homologous and heterologous skin test reactions in sensitized guinea pigs to antigens from 11 species of mycobacteria were fitted by a linear model that permitted the ranking of each species on the basis of cross reactivity. When the same species were ranked on the basis of in vitro transformation of sensitive lymphocytes in response to homologous and heterologous antigen preparations, a different ranking order was observed. Reasons for the lack of strict correlation between skin tests and in vitro lymphocyte transformations are discussed.