02556nas a2200373   4500000000100000008004100001260001600042653002400058653002000082653002700102653002000129653002000149653001100169653002200180653001200202653002600214653002100240653002500261653001800286100001400304700001500318700001700333700001800350700001300368700001200381700001400393700001800407245012700425300001100552490000800563050001400571520158300585022001402168       1999                            d  c1999 Jun 0110aAntigens, Bacterial10aEpitope Mapping10aEpitopes, T-Lymphocyte10aHLA-DR Antigens10aHLA-DR3 Antigen10aHumans10aImmunophenotyping10aleprosy10aLymphocyte Activation10aMolecular Weight10aMycobacterium leprae10aT-Lymphocytes1 aThole J E1 aJanson A A1 aCornelisse Y1 aSchreuder G M1 aWieles B1 aNaafs B1 aVries R R1 aOttenhoff T H00aHLA-class II-associated control of antigen recognition by T cells in leprosy: a prominent role for the 30/31-kDa antigens.  a6912-80 v162  aTHOLE19993 a<p>The recognition of 16 mycobacterial Ags by a panel of T cell lines from leprosy patients and healthy exposed individuals from an endemic population was examined within the context of expressed HLA-DR molecules. Although overall no significant differences were found between the frequencies of Ag recognition in the different subject groups, when Ag-specific T cell responses were examined within the context of HLA-DR, a highly significant difference was found in the recognition of the 30/31-kDa Ag. HLA-DR3 appeared to be associated with high T cell responsiveness to the 30/31-kDa Ag in healthy contacts (p = 0.01), but, conversely, with low T cell responsiveness to this Ag in tuberculoid patients (p = 0.005). Within the group of HLA-DR3-positive individuals, differences in 30/31-kDa directed T cell responsiveness were highly significant not only between healthy individuals and tuberculoid patients (p < 0. 0001), but also between healthy individuals and lepromatous patients (p = 0.009), and consequently between healthy individuals compared with leprosy patients as a group (p < 0.0001). A dominant HLA-DR3-restricted epitope was recognized by healthy contacts in this population. It has been proposed that secreted Ags may dominate acquired immunity early in infection. The low T cell response to the secreted, immunodominant 30/31-kDa Ag in HLA-DR3-positive leprosy patients in this population may result in retarded macrophage activation and delayed bacillary clearance, which in turn may lead to enhanced Ag load followed by T cell-mediated immunopathology.</p>  a0022-1767