CD66B, CD66C AND CARCINOEMBRYONIC ANTIGEN (CEA) ARE INDEPENDENTLY REGULATED MARKERS IN SERA OF TUMOR PATIENTS

Non-specific cross-reacting antigens (NCA-95 = CD66b and NCA-50/90 = C D66c) are members of the CEA (carcinoembryonic antigen = CD66e) family . Analysis of mRNA levels of CD66c in colon tumors suggests that this antigen is strongly up-regulated compared to its normal counterpart an d could, therefore, be of clinical interest. CD66c is also expressed i n normal lung and spleen tissues and, above all, on granulocytes. The appearance of CD66b in serum, the only strictly granulocyte-specific a ntigen, could point to the involvement of granulocytes in disease. Spe cific sandwich ELISAs have been established to determine CEA, CD66b an d CD66c levels in serum. Controls have been carried out by testing ser a from patients with benign tumors or inflammatory diseases and from h ealthy individuals. In sera of most patients suffering from solid tumo rs, sensitivities for CD66c are comparable to or lower than those for CEA. CD66c showed a much higher sensitivity in early colon tumor stage s. Sensitivities over 40% have been determined for CD66b in sera of pa tients with uterine and kidney carcinomas. CML patients revealed sensi tivities of 84% for CD66c and 47% for CD66b. investigations of sera fr om patients with inflammatory colon diseases which are negative for CE A showed high sensitivity for CD66c but not for the granulocyte-specif ic CD66b. Patients with mastopathy revealed sensitivities of over 40% for both CD66c and CD66b. CD66b, CD66c and CEA are independently regul ated proteins in a high percentage of patients. The simultaneous deter mination of CEA and CD66b/c can increase the sensitivities for maligna nt tumors but high sensitivities of CD66b/c for benign diseases limit their usefulness as tumor markers. CD66b may be interesting as a marke r for kidney and corpus carcinomas, for which good markers are not yet available. (C) 1995 Wiley-Liss, Inc.