Which antibodies are contained in the rabbit polyspecific antihuman globulin reagent for the detection of in vivo sensitization?

The correct response highlights the presence of specific antibodies that are crucial for the detection of in vivo sensitization in hemagglutination reactions. The rabbit polyspecific antihuman globulin reagent, often utilized in blood banking, contains antibodies against IgG and complement component C3d.

C3d is a protein fragment that is part of the complement system and is involved in the opsonization process, marking pathogens for destruction by immune cells. When red blood cells have been coated with IgG antibodies in vivo, the addition of the antihuman globulin reagent enables the detection of these sensitized cells through agglutination. The inclusion of anti-C3d is particularly important because it can indicate complement activation and further sensitization of red blood cells, facilitating identification of immune-mediated hemolytic anemia.

While anti-IgG is essential for detecting sensitization through antibodies, anti-IgM and anti-C3a are not specifically included in the polyspecific reagent for this purpose. Therefore, focusing solely on anti-IgG and anti-C3d accurately describes the composition required for effective detection in this context.