Choriogonadotropin-like antigen in an anaerobic bacterium, Eubacterium lentum, isolated from a rectal tumor.

Using the indirect fluorescein-labeled and indirect peroxidase-antiperoxidase-labeled immunohistochemical techniques, and utilizing both antiserum specific for the beta-subunit of choriogonadotropin and antiserum for the total hormone, we have demonstrated the presence of a choriogonadotropin-like immunoreactive material in a strain of Eubacterium lenthum that was originally isolated from a rectal tumor. In contrast, both immunohistochemical reactions were negative when applied to a strain of Corynebacterium parvum and to pathogenic and nonpathogenic strains of Agrobacterium tumefaciens. Our results demonstrate for the first time the expression of the choriogonadotropin-like antigen in an obligate anaerobe and support our previous findings that the choriogonadotropin like material appears to be expressed only in "cancer-associated bacteria" but that not all bacteria associated with the malignant neoplasms have the capacity to express the antigen, at least in amounts detectable by immunohistochemistry.