SUMMARY Eluates were prepared by high salt extraction from normal colonic mucosa and adenocarcinomatous tissue from 28 patients, eight more from unmatched colonic tissue and five from patients with other gastrointestinal disease. Immunoglobulins were detected by ELISA: IgG was present in 24% eluates from normal colon and 21% from carcinomas; IgA in 55% eluates from normal colon and 39% from carcinomas; IgM in 55% from normal colon and 37% from carcinomas. Cytomegalovirus-specific antibody was found in 15% eluates from normal colon and in 18% carcinomas. Out of the 28 matched specimens, cytomegalovirus-specific IgG was detected in one normal and four tumour eluates, specific IgA in two normal and four tumour eluates, and specific IgM in two normal and two tumour eluates. In two instances cytomegalovirus-specific antibody was present in the eluates prepared from the normal and tumour tissue of the same patient. Of those eluates which contained cytomegalovirus-specific antibodies by ELISA, two were positive by anti-complement immunofluorescence of human embryo fibroblasts infected with cytomegalovirus strain AD-169. It seems possible, therefore, that cytomegalovirus antigens on colonic cells may be masked by complexing with anticytomegalovirus antibodies, and may not therefore be detected by techniques such as immunofluorescence.Most cytomegalovirus infections of man are asymptomatic although they can occasionally result in congenital defects, infectious mononucleosis, interstitial pneumonia, hepatitis, and other severe diseases. 1 After the primary infection, the virus persists in the body by unknown mechanisms and in unknown sites, although peripheral blood leucocytes seem to represent one cell population from which virus can be recovered on occasion.There has been suggestive evidence that cytomegalovirus may be involved in the pathogenesis of certain types of cancer, particularly Kaposi's sarco-
