Granulomatous hypersensitivity to trehalose-6,6'-dimycolate (cord factor) in mice infected with BCG.

Cord factor in the form of emulsion is unable to sensitize mice to react with a more extensive granulomatous response to a subsequent challenge with the same substance. Mice infected with BCG bacilli are sensitized to cord factor. Such animals react to administration of cord factor with a very extensive granulomatous response, much stronger than normal ones. This hypersensitivity seems to be specific and is distinct from delayed hypersensitivity to PPD. PPD, administered to mice sensitized with BCG bacilli, has no effect on the granulomatous response. Our findings and their importance are discussed.