THE EXPRESSION OF ST2 GENE IN HELPER T-CELLS AND THE BINDING OF ST2 PROTEIN TO MYELOMA-DERIVED RPMI8226 CELLS

The ST2 gene, which is specifically induced by growth stimulation, enc odes interleukin-1 receptor-related proteins. Using the RT-PCR method, we found that the ST2 gene was broadly expressed in hematopoietic cel l lines. It was also expressed specifically in helper T cell lines amo ng lymphocytic cell lines. We analyzed the expression of ST2 in mouse helper T cell subsets with Northern blotting analysis. Mouse Th1 cell lines so far studied did not express ST2 mRNAs. On the other hand, one of the Th2 cell lines, D10, expressed ST2L (transmembrane form) witho ut stimulation, while co-stimulation by PMA and A23187 induced ST2 (so luble form) mRNA. These results suggest that the ST2 gene is involved in the regulation of the immune system. IL-1 alpha, IL-1 beta, and rec eptor antagonist did not bind to ST2L protein, which prompted us to se arch for the specific ligand of ST2. The recombinant human ST2 protein was purified and labeled with FITC. The labeled human ST2 protein bou nd with myeloma-derived RPMI8226 cells among the various B-cell lines, indicating possible involvement of ST2 in T-cell/B-cell interaction.