What is the likely antibody for a patient with a 2+ reaction at IAT and a complete red cell phenotype of Group A, R2R2, K-k+, M+N+S-s+, Jk(a-b-), Fy(a-b+)?

In the context of the presented patient, the identification of Anti-Jk3 as the likely antibody is rooted in the complete red cell phenotype provided. The patient shows a phenotype of Group A, R2R2, K-k+, M+N+S-s+, Jk(a-b-), and Fy(a-b+).

The important aspect here is the expression of the Jk(a) and Jk(b) antigens. The patient is Jk(a-b-), which indicates that they do not possess either the Jk(a) or Jk(b) antigens on their red blood cells. The presence of Anti-Jk3 is significant because the Jk3 antigen is a public antigen found on all individuals who have either the Jk(a) or Jk(b) antigen. Therefore, a person who lacks both Jk(a) and Jk(b) will produce Anti-Jk3.

This patient’s antibody reaction of 2+ at the Indirect Antiglobulin Test (IAT) suggests a strong and clinically meaningful antibody, which is consistent with the presence of Anti-Jk3 in someone with a Jk(a-b-) phenotype.

In contrast, antibodies against other specificities such as Anti-k, Anti