The VEL blood group system (ISBT 034) consists of only one antigen—VEL. It is a high-prevalence antigen with very weak expression on cord blood and variable expression from one individual to another, which can lead to the misidentification of anti-VEL as an "HTLA" antibody.
Disease Association
Anti-VEL activates complement and is considered clinically significant as it has been implicated in HTRs and HDFN.
Treatment
VEL antigens are resistant to enzymes and trypsin/alpha-chymotrypsin but have variable sensitivity to disulfide bond-reducing agents. The most reliable method of identification is with antigen-negative blood or antigen typing the patient with plasma containing a known anti-VEL.
Common Findings
Anti-VEL is often a mixture of IgM and IgG, so incubating a suspected anti-VEL at room temperature in place of an immediate spin reading may be helpful, though most instances of anti-VEL primarily demonstrate at the AHG phase.
