Exploration of rabbit integrin β3 as a possible immune-tolerizing agent to prevent foetal and neonatal alloimmune thrombocytopenia.

Abstract

Foetal and neonatal alloimmune thrombocytopenia (FNAIT) is a disease caused by the production of antibodies by the mother to the platelets of the foetus. The alloimmune response is caused by a P33L substitution in the Human Platelet Antigen-1a (HPA-1a) in a homo- or heterozygous HPA-1a foetus, in a homozygous HPA-1b+ mother. Maternal antibodies are produced by activated HPA-1a specific T-cells able to bind the DRB3*01:01-HPA-1a antigen complex. DRB3*01:01 can also bind some other antigen peptides with hydrophobic residues amino acids at position 33 like valine, like rabbit integrin β3 has. 3 main aims will be followed, determine if HPA-1a specific antibodies can bind rabbit platelets. Examine whether rabbit platelets can activate HPA-1a specific T-cells. To examine whether HPA-1a specific T cells can specifically recognize and be activated by rabbit integrin β3 protein, rabbit integrin β3 therefor needs to be isolated. The rationale being to determine if rabbit integrin β3 is a viable antigen for oral tolerance therapy. A protein database was used for animal and human integrin β3 comparison for examination of theoretical binding capabilities of DRB3*01:01 and mAb 26.4 to various integrins and showed rabbit integrin β3 as compatible for both. TNF-α and proliferation assays were performed and showed rabbit integrin β3 is a viable activator of HPA-1a specific cells both for immediate and long term T-cell responses. integrin β3 isolation via affinity chromatography was attempted but shown to be unsuccessful via western blot. Thus, rabbit integrin β3 in platelet, protein or peptide form could potentially be used for oral tolerance therapy development.