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Investigating Weak Antibodies

In this case study the patient's antibody has disappeared from the plasma by adsorbing to transfused donor red cells. It is detectable but unidentifiable in the post-transfusion red cell eluate.

Several trial and error procedures exist to enhance weak antibodies. Which methods will enhance the reactivity of a given antibody depend on its characteristics.

Methods to investigate weak antibodies include:

  • Use a higher plasma-to-red cell ratio (add more antibody-containing plasma or eluate)
  • Increase incubation time (if consistent with manufacturer instructions and if applicable)
  • Use enzyme-treated panel red cells (enzymes enhance IgG antibodies in Rh and Kidd blood systems but denature some antigens, e.g., Fya, Fyb, S)
  • Try alternative antibody detection methods. For example, if LISS is used routinely, try polyethylene glycol (PEG) or column agglutination methods such as gel, providing they have been validated for use in the transfusion services laboratory.