It has been shown that red cells sensitized with anti-Rh antibody are agglutinated by anti-γ-globulin sera, regardless of the "order" of Rh antibody activity. Red cells sensitized with anti-Lewis antibody, on the other hand, are agglutinated by anti-sera to non-γ-globulin substances. Of six other blood group antibodies studied, five provided γ-globulin red cell coating materials and one, an anti-Kidd, a non-γ-globulin material. The participation of complement, or complement-like, substances was shown in some instances.
Various pitfalls in the technics employed in absorbing Coombs sera so as to render them immunochemically specific are discussed.