Incidence of Wra antigen and anti-Wra in a Spanish population

BACKGROUND: This study reports the incidence of Wr(a) antigen and anti-Wr(a) in Valencia, Spain. STUDY DESIGN AND METHODS: The incidence of the Wr(a) antigen in 110,000 healthy blood donors was estimated. Likewise, the incidence of anti-Wr(a) was analyzed in a population consisting of 730 healthy blood donors, 356 pregnant women, and 581 patients who received transfusions from the area of Valencia, Spain. RESULTS: The incidence of Wr(a) antigen was 1 in 785. Overall, anti-Wr(a) was found in 59 samples: 20 healthy blood donors (1/37), 18 pregnant women (1/20), and 21 patients who received transfusions (1/28). The most frequent immunoglobulin class of anti-Wr(a) in healthy blood donors was immunoglobulin M, either alone (8 cases) or plus immunoglobulin G (IgG; 8 cases); the IgG1 and IgG3 were the IgG subclasses most frequently detected in pregnant women (12 cases) and in patients who received transfusions (12 cases). Only 51 percent of the anti-Wr(a) appeared to have the potential to be clinically significant. CONCLUSION: These data show that the incidence of Wr(a) antigen and anti-Wr(a) among the population from Valencia is similar to that reported in other European areas and suggest that the development of anti-Wr(a) is facilitated by the presence of a hyperactive immune system. The clinical relevance of anti-Wr(a) is limited, however.