Isoantigens A, B, and H in morphologically normal mucosa and in carcinoma of the larynx.

A modified Coombs' mixed cell agglutination reaction was performed on biopsy specimens of 24 patients with squamous cell carcinoma of the larynx. Isoantigens A, B, and H(O) were absent in 15 cases, partially lost in eight, and completely retained in one case. In four cases the initial biopsy specimens were histologically benign yet negative for isoantigens. In subsequent biopsies these showed the presence of carcinoma. The morphologically normal-appearing squamous mucosa adjacent to a carcinoma was found to be devoid of isoantigens in ten cases. The investigation suggested that isoantigenic alteration as detected by mixed cell agglutination reaction was a sensitive sign, since it occurred in squamous mucosa prior to recognizable morphologic change for malignancy. The reaction may represent a functional dedifferentiation in cancerous tissue, analogous to but sometimes preceding morphologic dedifferentiation. The results were comparable to those in previous studies of neoplasms of various other anatomic sites.