DIFFERENCES IN PROCESSING OF AN AUTOANTIGEN BY DR4-DW4.2 AND DR4-DW14.2 ANTIGEN-PRESENTING CELLS

Variations in antigen processing can influence class II-restricted T c ell responses. We now report a highly significant difference (p < 0.00 1) between the ability of antigen-presenting cells from three HLA-DR4: Dw14.2 (Arg(71)) and six DR4:Dw4.2 (Lys(71)) individals to present rec ombinant or native acetylcholine receptor antigens to a myasthenia gra vis T cell clone. The difference was greatest with longer antigens, an d not seen with short synthetic peptides, suggesting that it may resul t from a difference in antigen processing between the two alleles. The results were not related to the presence of myasthenia gravis or of s teroid therapy. They could, however, be of relevance in rheumatoid art hritis where particularly severe disease associates with Dw4.2/Dw14.2 heterozygosity.