LILRB1 polymorphisms influence posttransplant HCMV susceptibility and ligand interactions
Kang Yu, … , Swiss Transplant Cohort Study, Deborah N. Burshtyn
Kang Yu, … , Swiss Transplant Cohort Study, Deborah N. Burshtyn
Published March 12, 2018
Citation Information: J Clin Invest. 2018;128(4):1523-1537. https://doi.org/10.1172/JCI96174.
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Research Article Immunology Infectious disease

LILRB1 polymorphisms influence posttransplant HCMV susceptibility and ligand interactions

Abstract

UL18 is a human CMV (HCMV) MHC class I (MHCI) homolog that efficiently inhibits leukocyte immunoglobulin-like receptor subfamily B member 1 (LILRB1)+ NK cells. We found an association of LILRB1 polymorphisms in the regulatory regions and ligand-binding domains with control of HCMV in transplant patients. Naturally occurring LILRB1 variants expressed in model NK cells showed functional differences with UL18 and classical MHCI, but not with HLA-G. The altered functional recognition was recapitulated in binding assays with the binding domains of LILRB1. Each of 4 nonsynonymous substitutions in the first 2 LILRB1 immunoglobulin domains contributed to binding with UL18, classical MHCI, and HLA-G. One of the polymorphisms controlled addition of an N-linked glycan, and that mutation of the glycosylation site altered binding to all ligands tested, including enhancing binding to UL18. Together, these findings indicate that specific LILRB1 alleles that allow for superior immune evasion by HCMV are restricted by mutations that limit LILRB1 expression selectively on NK cells. The polymorphisms also maintained an appropriate interaction with HLA-G, fitting with a principal role of LILRB1 in fetal tolerance.

Authors

Kang Yu, Chelsea L. Davidson, Agnieszka Wójtowicz, Luiz Lisboa, Ting Wang, Adriana M. Airo, Jean Villard, Jeremie Buratto, Tatyana Sandalova, Adnane Achour, Atul Humar, Katia Boggian, Alexia Cusini, Christian van Delden, Adrian Egli, Oriol Manuel, Nicolas Mueller, Pierre-Yves Bochud, Swiss Transplant Cohort Study, Deborah N. Burshtyn

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Figure 4

Binding of soluble LILRB1 variants to HLA-I molecules and HCMV-UL18.

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Binding of soluble LILRB1 variants to HLA-I molecules and HCMV-UL18. (A)...
(A) Representative analysis of purified LILRB1 D1D2-Fc fusion proteins by Coomassie blue staining (left) and α–human IgG Fc Western blot (right). (B) Reactivity with α-LILRB1 (HPF1) was determined by ELISA over the indicated range of concentration of the LILRB1-Fc protein. Results shown are the average of 3 independent tests for the same batch of protein; error bars represent SD. (C) The top histograms illustrate binding of purified LILRB1-Fc to 221 cells with HLA-B58, HLA-Cw15, and HLA-G by flow cytometry at 50 μg/ml. The middle panels show 1 representative titration plotted as the MFI. The bottom series of plots show the normalized binding results aggregated from 3 independent tests. *P < 0.05 using 1-way ANOVA. (D) Cells expressing HLA-I were incubated with 10 μg/ml α-MHCI (W6/32) or the isotype antibody before addition of 50 μg/ml LILRB1 variants or Fc control. The binding was measured by flow cytometry. The plots shown are a representative result of 3 independent tests. (E) Binding of LILRB1–D1D2-Fc variants to UL18 expressed on 721.221 cells. The flow histogram on the left shows the binding of UL18 with 100 μg/ml Fc fusion proteins. The middle plot shows a representative experiment across 4 concentrations. The far-right graph shows the aggregate data for 3 experiments normalized as described in Methods (*P < 0.05 using 1-way ANOVA). (F) Expression of the LILRB1-PTTI and -LAIS variants on transduced RBL cells was measured by α-HA or α-LILRB1 (HPF1) staining (representative of 3 independent tests). (G) UL18-Fc binding to LILRB1 variants expressed on RBL cells shown in F with a representative histogram shown on the left at 300 nmol. The binding data are normalized by the MFI for α-HA (middle) or α-LILRB1 (HPF1) (far right). The results are representative of 3 independent tests.