EXPRESSION OF CARCINOEMBRYONIC OR RELATED CROSS-REACTING ANTIGENS IN PRIMARY PEDIATRIC NEUROECTODERMAL BRAIN-TUMORS

Various amounts of carcinoembryonic antigen (CEA) or cross-reacting antigen (CRA) were expressed in eight childhood primitive neuroectodermal tumors (PNETs) and in three of 12 astrocytomas (ASTR) using frozen section immunocytology. The antigen detection was performed using two recently developed anti-CEA monoclonal antibodies (MoABs), B.18.7.7 and D.14, reacting with a CEA specific antigenic epitope. Unfortunately, the two new MoABs also demonstrated cross-reactivity with nonspecific cross-reacting antigens (i.e., NCA-55) specific for the intratumoral granulocytes and cytotoxic mononuclear effector cell population. Three of eight PNETs contained 1 to 10% of CEA- or CRA-positive brain tumor cells. In two of eight, the antigenic epitopes were found in 10 to 50% of tumor cells, and in three of eight a large population (50 to 90%) of such cells was detected. Three pilocytic ASTRs contained CEA or CRA in 1 to 10% of cells. CEA or CRA positivity was located both on the cell surface and intracellularly in both tumor types. CEA or CRA expression in both tumor types was detectable only in fresh frozen sections and D.14 was preferable to B.18.7.7. The three pilocytic ASTRs lost CEA or CRA reactivity after formalin fixation and paraffin embedding. CEA-related cross-reacting antigen (NCA55) was detected on the cell surfaces of tumor-infiltrating mononuclear cells, macrophages, neutrophilic granulocytes, and probably in some brain tumor cells also.