Antibody Screening

• The purpose of this is to highlight the presence of allo-antibodies against red cells in recipient plasma.
• This allows for suitable units to be selected and minimises the risks of haemolytic transfusion reactions.
• Antibody screening is advantageous over serological crossmatching in picking up allo-antibodies as:
  • Screening cells with homozygous antigen expression are more sensitive for picking up antibodies which show dosage.
  • Antigens are better preserved on screening cells.
• A low ionic strength solution (LISS) IAT is considered the most suitable for detection of clinically-significant antibodies due to its speed, sensitivity and specificity.
• BCSH guidelines specify that the screening panel should include:
  • One R₁R₁ cell (DCe/DCe)
  • One R₂R₂ cell (DcE/DcE)
  • The following antigens: K, k, Fy^a, Fy^b, Jk^a, Jk^b, M, N, S, s, P₁, Le^a and Le^b.
  • At least one cell must be homozygous for Fy^a, Fy^b, Jk^a, Jk^b, S and s.
    • This is based on UK data regarding the incidence of DHTRs and the need for sensitive detection of Kidd antibodies.
    • Antibodies against these antigens show dosage.
• Cells should be stored in temperature-controlled environment to minimise loss of blood group antigens.
• Autologous controls do not form part of standard antibody screens.
• Use of controls is recommended, in particular for labile antigens such as Fy^a. In such cases, the control should be weak examples of antibodies.
• Controls should be selected such that each screening cell is expected to give a positive or negative reaction.

• For all IAT negative results, agglutination should occur when check cells (IgG-coated cells) are added. This validates the washing phase of the IAT. If the result is negative, then the test is invalid and should be repeated from the beginning.

Other Resources:

• BCSH Guideline: Pre-Transfusion Compatability Procedures (2012)