Non-ABO red blood cell antibodies in transplant patients

Transplant patients may have circulating non-ABO red blood cell (RBC) antibodies, but the influence of RBC alloimmunization on solid-organ transplantation outside of the ABO blood group system is not well known. Though RBC antigens have been identified in or on cells other than RBCs, the incidence of non-ABO RBC antibodies in transplant patients has had limited investigation. Identification of non-ABO RBC antibodies in transplant patients may help clarify cases of suspected antibody-mediated rejection (AMR) when human leukocyte antigen (HLA) donor-specific antibodies (DSA) cannot be detected.

This investigation tested for the presence and specificity of commonly encountered non-ABO RBC antibodies in the serum of transplant patients (heart, lung, and kidney), using standard hemagglutination antibody screening and antibody panel identification methods.

Of 135 patients, six (4%) tested positive for clinically significant non-ABO RBC antibodies. The antibodies identified were anti-K and anti-Fy^a.

This study provides new evidence for the transfusion and transplant community by documenting the frequency of non-ABO RBC antibodies in heart, lung, and kidney transplant patients, and is an important first step in determining the clinical significance of these antibodies in cases of suspected AMR when HLA DSAs are absent.