Anti-Lsa. Case study of an antibody to a low-incidence antigen

An antibody to the low-incidence antigen Lsa (Lewis II) was discovered during routine pre-operative antibody screening of an 87-year-old white man. This example of anti-Lsa reacted only in the indirect antiglobulin test. The antibody did not react with Ls(a+) red cells treated with either ficin or papain. Treatment of the serum with 2-mercaptoethanol did not reduce the reactivity of the antibody. No antibody activity had been detected during previous hospital admissions.