Figure 1: Flow diagram of the AMS-ELISA shown for the detection of HLA class I molecules. (A) Binding of the donor’s solubilized HLA class I molecules by monoclonal capture antibodies recognizing a monomorphic epitope on HLA class I molecules. (B) Binding of the donorspecific anti-HLA antibodies out of the recipient’s serum to the HLA molecules of the donor. (C) Binding of alkaline phosphatase-conjugated secondary antibodies to the recipient’s bound donor-specific anti-HLA class I antibodies and subsequent color reaction. The original protocol was modified by substituting the human IgG-specific by a human IgG/M/A-specific secondary antibody. (D) Lysate control using an alkaline phosphatase-conjugated monoclonal detection antibody directed against a second monomorphic epitope to confirm the immobilization of a sufficient amount of HLA molecules by the solid-phase-bound capture antibody. The AMS-ELISA variant for the identification of donorspecific antibodies directed against HLA class II molecules is correspondingly designed.