FINE-SPECIFICITY DIFFERENCES IN THE RECOGNITION OF AN ENCEPHALITOGENIC PEPTIDE BY T-HELPER 1 AND 2 CELLS

The lymphokine production of two T-cell clones, which both recognize e pitopes within the encephalitogenic 139-151 sequence of myelin proteol ipid protein, was examined after stimulation with immobilized antibodi es to the CD3 moiety. of the T-cell-receptor complex. Clone Al produce d interleukin (IL)-2 and interferon (IFN)-gamma, but no IL-4, while cl one D5 produced IL-4, but no IL-2 or IFN-gamma. Al therefore belongs t o the T-helper type 1 (Th1) subset, while D5 is a Th2 clone. In additi on, the Th1 clone induced severe experimental allergic encephalomyelit is (EAE), while the Th2 clone did not induce any signs of EAE. Synthet ic peptides were used to demonstrate that these clones recognized slig htly different epitopes within the 139-151 sequence. Histidine 139 was shown to be optimal for the stimulation of the Th2 clone, while the p resence of this residue inhibited the stimulation of the Th1 clone. Th 2 cells specific for an encephalitogenic peptide may be important in t he regulation of encephalitogenic Th1 cells.