A new reagent (ZZAP) having multiple applications in immunohematology

Area of Science:

• Blood banking
• Immunology
• Biochemistry

Background:

• Direct antiglobulin test (DAT) detects IgG on red blood cells (RBCs).
• Accurate blood group phenotyping can be challenging with positive DAT.
• Current methods for removing IgG, like heat elution, can cause hemolysis.

Purpose of the Study:

• To evaluate the efficacy of ZZAP reagent in dissociating IgG from DAT-positive RBCs.
• To assess ZZAP's utility in improving blood group antigen typing and autoabsorption.
• To determine ZZAP's effect on various blood group antigens.

Main Methods:

• ZZAP reagent (0.1 M DTT + 0.1% cysteine-activated papain) applied to IgG-sensitized RBCs.
• Comparison of ZZAP treatment with individual components (DTT or papain alone).
• Rh and Kidd antigen typing performed post-ZZAP treatment.
• Warm autoabsorption tests compared between ZZAP and heat elution.

Main Results:

• ZZAP successfully dissociated IgG from RBCs in all 67 patients tested, reducing DAT strength.
• Accurate Rh phenotyping was achieved in 52 instances post-ZZAP, eliminating spontaneous agglutination.
• Kidd antigen typing was also successful after ZZAP treatment.
• ZZAP proved superior to heat elution for autoabsorption, removing more IgG with less hemolysis.
• ZZAP did not affect ABH, Rh, or Kidd antigens but denatured Duffy, MNSs, and Kell antigens.

Conclusions:

• ZZAP is a valuable reagent for dissociating IgG from DAT-positive RBCs.
• It facilitates accurate Rh and Kidd antigen typing and enhances warm autoabsorption tests.
• ZZAP's selective antigen denaturation aids in complex antibody investigations and Kell antigen characterization.