Which alloantibody(ies), Anti-C (Anti-C [antibody against RhC antigen]) or Anti-E (Anti-E [antibody against RhE antigen]), cannot be excluded according to antibody exclusion criteria?

Antibody Exclusion Criteria for Anti-C and Anti-E

Anti-C cannot be excluded according to antibody exclusion criteria. 1

Understanding Antibody Exclusion in Blood Transfusion

The American Society of Hematology (ASH) guidelines strongly recommend prophylactic red cell antigen matching for Rh antigens, including C and E, to prevent alloimmunization in patients receiving blood transfusions 1. When evaluating which antibodies cannot be excluded, we must consider the clinical significance and potential for causing hemolytic transfusion reactions.

Clinical Significance of Anti-C vs. Anti-E

• Anti-C antibody:

  • Anti-C is a clinically significant antibody that can cause both acute and delayed hemolytic transfusion reactions 2
  • The ASH guidelines specifically note that patients with hybrid RHDDIIIa-CE(4-7)-D or RHCECeRN alleles, which encode partial C antigen, should be transfused with C-negative red cells to prevent allo-anti-C development 1
  • This special consideration for C antigen indicates it cannot be excluded from antibody screening protocols

• Anti-E antibody:

  • While Anti-E can cause delayed hemolytic transfusion reactions and occasionally acute reactions 3
  • It is routinely included in standard prophylactic matching protocols 1
  • The guidelines do not specify special exclusion criteria for Anti-E that would prevent it from being excluded in certain scenarios

Evidence from Guidelines

The ASH 2020 guidelines for transfusion support explicitly recommend:

1. Prophylactic red cell antigen matching for Rh (C, E or C/c, E/e) and K antigens for patients receiving transfusions 1
2. Extended red cell antigen profiling by genotype or serology that includes C/c, E/e, K, and other antigens 1
3. Special consideration for patients with certain genetic variants affecting C antigen expression 1

The guidelines specifically state: "Patients identified by genotype with the hybrid RHDDIIIa-CE (4-7)-D or RHCECeRN alleles, which encode partial C antigen, and no conventional RHCE*Ce or *CE allele should be transfused with C-negative red cells to prevent allo-anti-C development." 1

This special provision for Anti-C indicates that it cannot be excluded from antibody screening protocols, particularly in patients with these genetic variants.

Clinical Implications

The inability to exclude Anti-C has important clinical implications:

• Patients requiring transfusion must be tested for Anti-C antibodies
• C-negative blood must be provided to patients with Anti-C antibodies
• Special attention must be given to patients with genetic variants affecting C antigen expression

Conclusion

Based on the ASH guidelines and supporting evidence, Anti-C cannot be excluded according to antibody exclusion criteria, particularly in patients with specific genetic variants affecting C antigen expression. While Anti-E is clinically significant, it does not have the same specific exclusion criteria mentioned in the guidelines.