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%), P(1) (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 -P(1).
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.