Improved hepatic and pancreatic localisation of the equine alpha-1-proteinase inhibitor family of serpins using an antigen enhancement technique and a monoclonal antibody.

The research focused on studying the distribution pattern of equine alpha-1-proteinase inhibitor (API) in horse tissue samples and has found novel tissue distribution patterns. The research used improved techniques for Affinity purified sheep polyclonal and protein A purified mouse monoclonal antibodies for antigen recovery and resulted in clearer immunostaining.

Objectives of the Research

• The main objective of this research was to investigate the immunohistochemical localisation of the equine alpha-1-proteinase inhibitor (API) in various equine tissue samples such as the liver, lung, stomach, pancreas, jejunum, and colon.
• The researchers also aimed to observe if any novel tissue distribution patterns could be identified using improved antigen recovery techniques.

Methods Used in the Research

• The research involved the use of paraffin embedded equine tissue samples which were fixed in paraformaldehyde.
• The antibodies used in the study were affinity purified sheep polyclonal and protein A purified mouse monoclonal antibodies. The specificities of these were confirmed using Western blotting.
• For enhanced antigen recovery, the tissue sections were exposed to boiling citrate buffer. This process greatly improved the immunostaining with both the antibodies used.

Key Findings of the Research

• The antigen enhancement technique highlighted novel tissue distribution patterns for equine API.
• In the studied horses, all hepatocytes exhibited varying degrees of cytoplasmic staining, with many showcasing perinuclear intense granular inclusions.
• This finding contrasts with human studies, where staining for human API in hepatocytes of Pi MM phenotype has often proven difficult, despite the molecular evidence proposing hepatocytes as the significant source of serum API.
• The observed discrepancy could be due to the use of different tissue fixation and antigen recovery techniques.
• In all other tissues examined, the distribution of equine API was consistent with findings from human studies.

By improving antigen recovery techniques and using specific antibodies, this study successfully explored the tissue distribution of equine API in horses, revealing novel patterns and contributing new, nuanced insights into this area of equine biology.