Detection and effects on platelet function of anti-platelet antibody in mule foals with experimentally induced neonatal alloimmune thrombocytopenia.

The research article discusses an experimental study on mule foals to investigate the occurrence and effects of anti-platelet antibody in neonatal alloimmune thrombocytopenia (a condition called NAIT, which can cause low platelet levels and bleeding). It was conducted on pregnant horse mares carrying mule foals and induced by immunization with acid-citrate-dextrose-anticoagulated donkey blood. The findings suggest that antibodies, potentially against a donkey platelet antigen, may be causing the thrombocytopenia in mule foals.

Experiment Design

• The researchers immunized horse mares carrying mule foals in their last trimester with whole acid-citrate-dextrose-anticoagulated donkey blood to experimentally induce neonatal alloimmune thrombocytopenia.

Results of the Study

• Thrombocytopenia (low platelet count leading to bleeding) occurred in mule foals born to these immunized mares within 24 hours of drinking their mothers’ colostrum. Conversely, mule foals born to mares not immunized with donkey blood did not develop thrombocytopenia.
• This indicated the possibility of antibodies being directed against a donkey platelet antigen present in the mule foals but not their mothers.

Objectives of the Study

• The primary goals of this study were to determine if anti-platelet antibody can be detected in affected mule foals, to identify any platelet proteins recognized by serum antibody in these foals, and to ascertain if the platelet function was altered by sera from these mule foals.

Methodology

• An indirect enzyme-linked immunosorbent assay demonstrated significantly higher absorption of platelet-bindable immunoglobulin G in serum from thrombocytopenic mule foals compared with foals that were not thrombocytopenic.
• Sera from thrombocytopenic and nonthrombocytopenic mule foals produced similar binding patterns in western immunoblots with donkey platelet proteins separated on sodium dodecyl sulfate polyacrylamide gels.

Conclusions

• Maximum platelet aggregation and the relative slope of aggregation in response to collagen were significantly inhibited after incubation with sera from thrombocytopenic mule foals.
• The results suggest that mule foals with induced alloimmune thrombocytopenia have serum antibodies that bind to platelets. This binding may compete with collagen binding sites, ultimately impairing platelet aggregation.