An immunological study of maple bark disease.

The immunological response of three groups of guinea-pigs to the spores of () was studied. The first group received spores only intradermally (i.d.) and all of eleven developed precipitating antibody and ten out of eleven developed a positive skin reactivity. The second group received the spores i.d. and were exposed to an airborne suspension of the spores. In this group all of fourteen developed precipitating antibody, all of fourteen developed a positive skin reactivity, and three out of fourteen developed granulomatous lung disease. The third group was exposed only to an airborne suspension of the spores. In this group nine out of ten developed a precipitating antibody, all of ten developed a positive skin test and two out of ten developed granulomatous lung disease. The skin reactivity was maximal at 24 hr and could be passively transferred with buffy coat cells but not with serum. This supports the hypothesis that there is a delayed hypersensitivity phenomenon in maple bark disease.