Antigenic relationships among thermophilic actinomycetes.

Antigens from Micropolyspora faeni, Saccharomonospora viridis, Thermoactinomyces candidus, T. sacchari and T. vulgaris were prepared by growing them on dialysate of trypticase soy broth. Sera from rabbits immunized with these antigens were used to study cross-reactivity between thermophilic actinomycetes by antigen-antibody crossed immunoelectrophoresis and by agar gel double diffusion. Mi. faeni and S. viridis showed some degree of cross-reaction, but both failed to show any cross reactivity with Thermoactinomyces species. Antigens from Thermoactinomyces cross-reacted with members within the genus, but no reactivity against S. viridis or M. faeni antisera was detected. Hence, the presence of antibodies to several thermophilic actinomycetes in the sera of patients may be attributed to the exposure of the individual to different thermophilic actinomycetes rather than to the antigenic cross-reactivity between the organisms.