Altered expression of cell surface membrane antigens in a common acute lymphoblastic leukemia-associated antigen-expressing neuroblastoma cell line (SJ-N-CG) with morphological differentiation

The expression of common acute lymphoblastic leukemia antigen (CALLA) on a human neuroblastoma cell line, SJ-N-CG, was demonstrated by indirect membrane immunofluorescence, complement-dependent cytotoxicity, and quantitative absorption, using two monoclonal antibodies (J-5 and BA-3) directed against CALLA. Immunoprecipitation of solubilized 125I-labeled membrane proteins from SJ-N-CG cells with J-5 antibody revealed a protein with a molecular weight of 100,000 as determined on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Morphological differentiation of SJ-N-CG cells could be induced in the presence of 2.0 mM dibutyryl adenosine 3'-5'-cyclic monophosphoric acid for 10 days of culture. Changes in cell surface membrane antigens associated with morphological differentiation were studied by indirect immunofluorescence and complement-dependent cytotoxicity using a panel of seven monoclonal antibodies. Increases in the antigens recognized by BA-2 (detecting leukemia-associated antigen), anti-Thy-1, and antibody 390 (Thy-1 antigen) were found in "differentiated cells," while those detected by BA-1 (B-cell-associated antigen) and J-5 (CALLA) were unchanged. In contrast, the antitransferrin receptor defined by B3/25 was inhibited, and expression of B7/21-defined la-like antigen was not induced. Kinetic studies on antigenic alterations showed that the expression of BA-2-defined antigen rose on Day 2 and remained at the same level until Day 10. The expression of CALLA was not changed from Days 2 to 10. The augmentation of Thy-1 antigen was noted on Day 4 and reached the maximum on Day 10. These results show that dibutyryl adenosine 3'-5'-cyclic monophosphoric acid is capable of inducing phenotypic changes in SJ-N-CG cells. The changes of expression of some antigens on exposure of cells to dibutyryl adenosine 3'-5'-cyclic monophosphoric acid may enable us to have a greater understanding of the differentiation of neuroblastoma to a more mature ganglioneuroblastoma phenotype.