Using the crossout technique, it appears that the antibody is anti-C. Based on the patient's history provided (para 2, gravida 4) we know that she has 2 living children and has had 4 pregnancies. She also has a history of ongoing red cell transfusions during dialysis procedures, exposing her to donor/foreign red cells.
Of note in this antigram is that cell number 5 reacts at a strength of 1+ whereas the other panel cells that react are 2+ in strength. It is not uncommon for Rh antibodies to demonstrate a phenomenon called dosage effect - that is, the antibody reacts better with cells that possess a double dose of the antigen (homozygosity of the donor) than with cells that possess a single dose of the antigen (heterozygosity of the donor).
This patient must receive red cell units that are C negative, have been crossmatched through the IAT (antiglobulin) phase, and found to be compatible. The patient's history must be maintained and the antibody must be "honored" regardless of antibody screen results in the future. It is not unusual for antibodies such as this to decrease in titer (below detectable level), however infusion of red cells that possess the antigen could stimulate a secondary response, causing a transfusion-related adverse event (transfusion reaction) in the patient.
