A patient's serum reacts with 2 out of 3 antibody screening cells at the AHG phase. The majority are incompatible. What is most likely present?

The situation described indicates that a patient's serum reacts with 2 out of 3 antibody screening cells, suggesting the presence of an antibody that targets specific antigens present on the red blood cells of those screening cells. The fact that the majority are incompatible points to the likelihood that the antibody in question is reacting specifically with antigens that are present on the screening cells.

In this context, the presence of anti-c is a strong possibility. The c antigen is part of the Rh system, and it is prevalent enough in the population that many screening cells used in antibody detection will express it. If the patient has anti-c in their serum, any screening cell that expresses the c antigen will show a positive reaction, while those that do not contain the c antigen will provide a negative reaction. This explain why the majority, or 2 out of 3, screening cells react positively with the patient’s serum.

The other antibody options provided (anti-M, anti-E, anti-Fy^a) could cause reactions as well, but their overall prevalence and the likelihood of detecting them in this specific scenario, given the results, make anti-c the most reasonable conclusion. It aligns with the reactions observed and the general frequency of Rh antigens in blood donors used in antibody