Which of the following is useful for removing IgG from red blood cells with a positive DAT to perform a phenotype?

Chloroquine is effective for removing IgG antibodies from red blood cells due to its specific action in dissociating IgG from the surface of the cells. In the context of a positive Direct Antiglobulin Test (DAT), which indicates the presence of antibodies bound to red blood cells, the use of chloroquine allows for a clearer analysis of the blood group antigens present on the surface of the cells. This is particularly important when performing phenotyping, as it enables accurate determination of the antigen expression without interference from the bound IgG antibodies.

Using chloroquine in this manner is crucial because it facilitates the identification of underlying blood group antigens that may have been obscured by the presence of the IgG coating. This is essential for ensuring appropriate blood transfusions and compatibility assessments.

In contrast, other options may not effectively achieve the same outcome when it comes to removing IgG, making chloroquine the preferred choice in this scenario.