ANTI-HNA-3 antibodies in kidney transplant rejection: is it an immunological risk factor?
Juliana Oliveira Martins1, Elyse Moritz1, Ana Jala Salum1, Renato de Marco2, Henrique Machado de Sousa Proença3, Helio Tedesco Silva Junior3, José Osmar Medina-Pestana3, Maria Gerbase-DeLima2, José O Bordin1.
1Department of Clinical and Experimental Oncology, Universidade Federal de São Paulo, UNIFESP, São Paulo, Brazil; 2Instituto de Imunogenética, IGEN, São Paulo, Brazil; 3Hospital do Rim, HRim, São Paulo, Brazil
Introduction: Human neutrophil antigens 3 (HNA-3a and HNA-3b) are located on choline transporter protein 2 (CTL2) and expressed on neutrophils, lungs, kidneys and other human tissues. Alloantibodies directed against these antigens are formed from allogeneic exposure and are mainly associated with transfusion-related acute lung injury (TRALI) and immune neutropenias, however due to the presence of this antigen in renal tissue and the doubt that HNA-3 alloimmunization may also be involved in cases of kidney transplant rejection, the study of the frequency of anti-HNA-3 antibodies in this context becomes a focus of great clinical relevance.
Objective: Investigate the presence of anti-HNA-3 antibodies in the serum of patients who had kidney transplant rejection.
Materials and Methods: A total of 604 patients with kidney transplant rejection were included in the study. The Granulocyte Agglutination Test (GAT) was performed as a screening test in all individuals included in the present study with a panel of granulocytes from at least three individuals previously genotyped for all HNA systems. Positive samples in GAT were tested using the microsphere-based technique (LABSCreen Multi kit, One Lambda); we analyzed the normalized background values ≥ 10 and immunofluorescence ≥ 1000 as a positive result for HNA-3 antibodies. HNA-3 genotyping by PCR-RFLP was performed only in individuals who had a positive result in serological techniques.
Results: We detected 85/604 (14.1%) positive samples in GAT and 11/85 positive samples in both GAT and LSM multi for anti-HNA antibodies. Regarding the specificity of these 11 samples, 6 (54.5%) individuals presented an anti-HNA-3b antibody confirmed by genotyping (HNA- 3a/HNA-3a). In addition to the anti-HNA-3b antibodies, other specificities of anti-HNA antibodies were also identified: 1/11 (9.1%) anti-HNA-1a, 2/11 (18.2%) anti-HNA-1b, 1/11 (9.1%) anti-HNA-FCγRIIIb and 1/11 (9.1%) anti-HNA-2. Furthermore, 14/85 (16.5%) individuals had anti-HLA antibodies detected by LSM multi: 8/14 (57.1%) class I, 3/14 (21.4%) class II and 3/14 (21.4) class I and II. No patient presented simultaneously anti-HNA and HLA antibodies.
Conclusion: Our data show that HNA-3b alloimmunization has a greater tendency in patients who rejected kidney transplantation compared to healthy blood donors (1.0% vs. 0.2% respectively, p=0.05). These findings indicate that the detection of anti-HNA-3b antibodies may allow a better understanding of patients' immune response against renal allograft when no HLA antibody is identified supporting evidence of immunological risk.
The authors would like to thank the recipients who participated in the study and the researchers at the Granulocyte Immunohaematology Research Laboratory for donating blood to perform the GAT and f low-WIFT. We would also like to thank the Coordination for the Improvement of Higher Education Staff [Personnel Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; CAPES] for granting the scholarship and financial aid that made this study possible and Biometrix for the technical support.
