Antigen‐processing organelles from DRB1*1101 and DRB1*1104 B cell lines display a differential degradation activity

摘要

AbstractWe have developed anin vitroassay for tetanus toxin (tt) C fragment (C‐fr) degradation. Purified endosomes (abbreviated endosomes 1101 or 1104) and lysosomes (abbreviated lysosomes 1101 or 1104) from the DRB1*1101 (Gly 86) and DRB1*1104 (Val 86) B cell lines were used to degrade125I‐labeled C‐frin vitro. Using three distinct methods of analysis, we show that the capacity of endosomes and lysosomes to degrade the tt C‐fr or tt synthetic Y‐P30 peptide differed. Using sodium dodecylsulfate‐polyacrylamide gel electrophoresis,125I‐labeled C‐fr degradation patterns observed either with endosomes 1101/1104 or lysosomes 1101/1104 are distinct both in terms of the number of fragments and the kinetics of generation of the fragments. These results were confirmed by high‐performance liquid chromatography analysis, where we observed that the elution profiles of the125I‐labeled Y‐P30 peptide digested by endosomes 1101/1104 were different compared to those obtained with lysosomes 1101/1104. Furthermore, the kinetics of degradation of125I‐labeled Y‐P30 were faster with lysosomes 1104 than with lysosomes 1101. This difference in activity of the 1101 and 1104 organelles was also found in a functional assay where we showed that the activation capacity of the P30 peptide was diminished when digested by lysosome 1104, regardless of the antigen‐presenting cell (APC) used, whereas endosomes 1101 or lysosomes 1101 modified P30 peptide in a form that discriminated between presentation by 1101 or 1104 APC. Taken together, these results suggest that the differential processing and presentation displayed by the DRB1*1101 and DRB1*1104 APC is due partly to a different enzymatic content and partly to the d