Properties of HLA class II molecules divergently associated with Goodpasture's disease

Abstract

Goodpasture's disease provides an opportunity to analyse molecular mechanisms that may underlie MHC class II associations with autoimmune disease because it is caused by autoimmunity to a defined antigen [the 230 amino acid NC1 domain of the alpha3 chain of type IV collagen (alpha3(IV)NC1)] and has strong HLA class II associations. We compared the alpha3(IV)NC1 peptide binding of class II molecules with strong positive (DR15) and dominant negative (DR7/1) associations using an inhibition binding assay and short synthetic peptides spanning the sequence of alpha3(IV)NC1. DR15 in general bound the peptides with low affinity (three of 23 < 100 nM) compared to DR1 and DR7 (12 and 10 < 100 nM respectively), and no peptide bound DR15 with much higher affinity (>10-fold) than both DR1 and DR7. Thus DR15 molecules are unlikely to increase susceptibility to Goodpasture's disease by presenting a particular alpha3(IV)NC1-derived peptide uniquely well and DR1/7 are unlikely to protect by their inability to present particular peptides. However DR1/7 could protect by capturing alpha3(IV)NC1 peptides and preventing their display bound to DR15; the binding data suggest that all the major (biochemically detectable) alpha3(IV)NC1 peptides presented bound to DR15 by DR15 homozygous antigen-presenting cells (APC) would bind preferentially to DR1/7 in DR15, 1/7 heterozygote APC.

Antibodies against Linear Epitopes on the Goodpasture Autoantigen and Kidney Injury

“…Previous studies have demonstrated that P14 contained the core sequence with highest predicted binding affinity with HLA-DR15 (25,26), which was proven to be the genetic marker for susceptibility to anti-GBM disease. The finding that a mutual T and B cell epitope exists in human anti-GBM disease, in accordance with the results from animal models, favors the hypothesis that certain nephrogenic linear epitopes might initiate the disease by stimulating both humoral and cellular responses.…”

The Fine Specificity and Cytokine Profile of T-Helper Cells Responsive to the α3 Chain of Type IV Collagen in Goodpasture’s Disease

“…A panel of 22 synthetic peptides, spanning the sequence of ␣3(IV)NC1, was screened for the ability to b The classification is based on biochemical identification of major sets of naturally processed and presented peptides from ␣3(IV)NC1 (15, 16) and on DR15/peptide binding data (16,17). Peptides that include the core of the sets of naturally processed sequences are marked NP.…”

“…They comprise three nested sets of peptides each centered on a common core. Furthermore, the affinity of a complete panel of overlapping ␣3(IV)NC1 peptides for DR15 has been established (16,17). Together, these studies reveal that the selection of the three nested sets for presentation is determined by dominant processing constraints, not solely by affinity for class II molecules (16,17).…”

“…In animal models, autoaggressive Th cells can survive such censorship if they recognize self-epitopes that are inefficiently presented as a result of low affinity for the restricting class II molecule (13) or processing constraints (14), but it is unclear whether similar mechanisms are important in human disease. Our previous work that analyzed the processing and presentation of ␣3(IV)NC1 (15)(16)(17) now enables us to address these issues in Goodpasture's disease. The major naturally processed ␣3(IV)NC1 peptides that are displayed bound to DR15 molecules have been identified directly after elution from antigen-pulsed, Epstein-Barr Virustransformed human B cells (15,16).…”

“…Furthermore, the affinity of a complete panel of overlapping ␣3(IV)NC1 peptides for DR15 has been established (16,17). Together, these studies reveal that the selection of the three nested sets for presentation is determined by dominant processing constraints, not solely by affinity for class II molecules (16,17). For the first time, this makes it possible to determine the relationship between the fine specificity of Th cells from patients with an autoimmune disease and the hierarchy with which peptides from the target autoantigen are presented.…”