The Interaction of LILRB2 with HLA-B is Associated with Psoriasis Susceptibility

Genetic variation within the major histocompatibility complex (MHC) class I is a well-known risk factor for psoriasis. While the mechanisms behind this variation are still being fully elucidated, human leukocyte antigen (HLA) presentation of auto-antigens as well as the interaction of HLA-B with killer cell immunoglobulin-like receptors (KIRs) have been shown to contribute to psoriasis susceptibility. Here we demonstrate that the interaction of HLA class I molecules with leukocyte immunoglobulin-like receptors (LILR), a related group of immunomodulatory receptors primarily found on antigen presenting cells, also contributes to psoriasis susceptibility. We used previously characterized binding capacities of HLA-A, HLA-B, and HLA-C allotypes to two inhibitory LILRs, LILRB1 and LILRB2, to investigate the effect of LILRB1/2 binding in two large genome wide association study cohorts of psoriasis patients and controls (N = 10,069). We found that the strength of binding of LILRB2 to HLA-B was inversely associated with psoriasis risk (p = 2.34E-09, OR [95% CI], 0.41 [0.30-0.55]) independent of individual class I or II allelic effects. We thus propose that weak binding of inhibitory LILRB2 to HLA-B may play a role in patient susceptibility to psoriasis via increased activity of antigen presenting cells.