LYMPHOCYTIC CD43 AND CD45 BEAR SULFATE RESIDUES POTENTIALLY IMPLICATED IN CELL-TO-CELL INTERACTIONS

CD43 is a major heavily glycosylated lymphocyte surface molecule. It h as been shown to play an important role in lymphocyte activation and c ell-cell interactions. Here we demonstrate that in human activated lym phocytes and CEM T cells, CD43 is a sulfated molecule. We also observe d that CD45, another lymphocyte surface glycoprotein, is a sulfated mo lecule. (SO42-)-S-35 incorporation would thus appear to be an appropri ate labeling method for CD43 and CD45 visualization. Moreover, we show that the level of cell surface protein sulfation can modulate CD43-me diated homotypic aggregation induced by CD43 monoclonal antibodies. It is well known that glycoprotein sulfation is required for various rec ognition phenomena. Since there are numerous potential sulfation sites on CD43 and CD45, these residues could play an important role in regu lating cell-cell interactions.