Which agglutination is used in blood group testing?
Blood grouping depends on detecting antigens naturally present on erythrocyte membrane such as A, B and RhD. When specific antiserum is mixed with whole blood, IgM antibodies bind directly to intrinsic surface antigens without requiring artificial carrier coupling. This direct agglutination occurs because red cells themselves act as particulate antigen, forming visible clumps without intermediate coating step. Passive agglutination involves antigens attached to latex or red cells secondarily, useful for soluble antigens. Fluorescent or double variants are not standard for routine ABO typing. H
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.