Immune Adherence Hemagglutination Assay v1

This protocol describes an Immune Adherence Hemagglutination (IAHA) assay used to detect and semi-quantitatively analyze circulating immune complexes and complement-activating sequences. The method is particularly effective for evaluating the immunogenicity of pathogenic coronavirus peptides and the neutralizing capacity of antipeptide antibodies. The procedure involves a multi-step incubation process: forming or introducing an immune complex (such as heat-aggregated plasma, tetanus toxoid mixtures, or COVID-19 peptide-sera complexes) in HBS++, followed by the addition of normal human plasma (NHP) as a complement source. A critical modification in this protocol is the use of N-Acetylcysteine (Nac) in lieu of traditional dithiothreitol (DTT) to stabilize the reaction before the addition of human erythrocytes. Results are interpreted via visual scoring of hemagglutination patterns on a U-bottom plate, where positive adherence indicates successful complement activation and receptor binding on the red blood cells. This protocol offers a scalable, non-radioactive alternative for monitoring humoral immune responses and viral pathogenesis.