Red blood cell alloantibody frequency, specificity, and properties in a population of male military veterans

BACKGROUND: The prevalence of red blood cell (RBC) alloantibodies among general, hospital‐based patients typically has averaged approximately 1 percent in various studies. The frequency and properties of RBC alloantibodies in military veterans has never been examined. STUDY DESIGN AND METHODS: Transfusion records of 18,750 military veterans at a Department of Veterans Affairs (VA) medical center were retrospectively reviewed. For patients with RBC alloantibodies, the following were collected: sex, race/ethnicity, decade of birth, transfusion history, alloantibody specificity, reaction phase(s), and whether alloantibodies were detected at the initial type and screen or later. RESULTS: The RBC alloantibody prevalence was 2.4 percent among predominantly male military veterans. Alloantibody prevalence varied with decade of birth, ranging up to 3.3 percent (1911‐1920). The 10 most frequent alloantibodies in males, as a percentage of total male antibodies, were K (21.9%), E (19.4%), D (9.1%), Le^a (7.4%), Fy^a (5.4%), c (4.8%), C (4.6%), P₁ (3.9%), Jk^a (3.7%), and Le^b (3.5%). Investigation of D alloimmunization in men revealed that antibody development occurred before VA care in 80 percent (39/49) of cases. For alloimmunization during VA care, anti‐D was mostly associated with the transfusion of D+ platelets (7/10). The majority of alloantibodies in males reacted at the antiglobulin (AG) phase, even anti‐Le^a, ‐Le^b, M, ‐Lu^a, and ‐P₁. CONCLUSION: Military veterans have a relatively high prevalence of RBC alloantibodies, including anti‐D, despite a large male predominance and lack of pregnancy‐related alloimmunization. Alloantibody prevalence was highest in World War II veterans. The majority of male alloantibodies reacted with AG, even those traditionally considered to be clinically insignificant.