3D analysis of CROMER (DAF) and a new antigen CRAG.

• DOI: 10.2450/2022.0285-21
• Publication Date: 2022-11-01
• Authors: Aline Floch; Sunitha Vege; Kim Hue‐Roye; Jan R Hamilton; Lance A. Williams; Jacquelyn Choate; Christine Lomas‐F...; Connie M. Westhoff

Cromer antigens are carried on decay accelerating factor (DAF, CD55), for which the crystal structure is available. We investigated two samples with an unidentified antibody to a high prevalence antigen and evaluate location characteristics of amino acids associated CD55 by 3D modelling.Antigen typing identification were standard methods. was sequenced, variants generated using protein's (1OK3, chain A). Antigen-associated residues intraprotein interactions in (Naccess, Protein Interactions Calculator).The sample from woman Kashmiri descent identified as anti-IFC (anti-CROM7). Her RBCs negative high-prevalence including IFC. sequencing revealed silent c.147G>A (p.Leu49=) c.148G>T (p.Glu50Ter) changes, designated CROM*01N.05. The Greek ancestry only compatible IFC- but her positive known antigens. found she homozygous c.173A>G (p.Asp58Gly). named CRAG (ISBT CROM18 or 021018) allele CROM*01.-18. By analysis, all antigen-associated residues, new antigen, exposed at protein surface. between within same domains identified.Identification antibodies can be challenging. surface exposure likely accounts their immunogenicity. analysis provides insight into previous serologic observations regarding influence some expression others.