DETECTION OF DISTINCT SETS OF NEWLY SYNTHESIZED POLYPEPTIDES IN SUPERNATANTS OF TCR-TRIGGERED T-CELL CLONES - IMPLICATION FOR THE SEARCH FOR NEW LYMPHOKINES

Using metabolic radiolabelling of proteins, which are newly synthesize d during TCR-triggered T cell activation we were able to visualize dis tinct patterns of secreted polypeptides (with molecular weights rangin g from 6 to 44 kDa) in supernatants of different T helper-1, T helper- 2 and cytotoxic T cell clones. Most of these detected proteins are sec reted in -response to TCR-crosslinking (or to combined action of PMA a nd A231287), in an extracellular Ca2+-dependent manner and their appea rance in supernatants was completely blocked by the addition of RNA sy nthesis or protein synthesis inhibitors or EGTA. Cyclosporin A (CsA) b locks secretion of several detected polypeptides, but does not affect TCR-triggered synthesis and secretion of others reflecting the existen ce of TCR-triggered, CsA-insensitive protein synthesis and secretion p athway. The insensitivity of secretion of several easily detectable po lypeptides to inhibition by CsA offers a promising approach to further define the CsA-resistant and calcineurin-independent molecular pathwa ys of TCR-triggered T cell activation. Several lymphokines (e.g., inte rferon-gamma, tumor necrosis factor, interleukin-4 and interleukin-10) are identified among the visualized set of secreted polypeptides. Sin ce other, yet unidentified, secreted polypeptides in the same set of s ecreted proteins share important properties with known lymphokines it seems promising to use described approach in search for new lymphokine s.