A collection of immunoglobulins capable of binding to individual classes of human immunoglobulin and/or complement components fixed to red blood cell antigens, and intended to be used together in testing a clinical specimen to detect red blood cell sensitization by specific molecules, using an agglutination technique. The specific molecules intended to be detected may include immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), C3c, and/or C3d.