Immunologic aspects of combined immunodeficiency disease in Arabian foals.

The research focuses on investigating a primary severe immune disease identified as a combined immunodeficiency disease (CID) in Arabian foals. The study deploys tests for T and B cells, looking into their quantity and function within the immune response.

Development of Immunological Tests

• The researchers developed tests to quantify T and B cells and assess their function in Arabian foals. This critical step allowed them to understand the specifics of the immune system in these foals better and the role of T and B cells play in combating diseases.
• Foals with CID showed severe lymphopenia, a condition characterized by low levels of lymphocytes in the blood. They also had minimal or zero B cells. This was determined through the application of various methodologies including immunofluorescence of surface immunoglobulin (Ig), erythrocyte-antibody-complement rosetting, and staphylococcal protein A rosetting.

Immunodeficiency in CID Foals

• In their findings, serum IgM was undetectable in four CID foals aged between 25 and 71 days. This indicates that these foals lacked necessary antibodies to initiate a proper immune response.
• The study also found that the foals could not produce antibodies in response to the potent antigen phage phi X-174, further supporting the conclusion that these foals have a severe immunodeficiency.

Potential Equine T Cell Marker

• The researchers examined nonspecific esterase (NSE) staining in a single vesicle format as a possible marker for equine T cells in the study. For normal foals, 64.0% of peripheral blood lymphocytes exhibited NSE staining. However, the percentages in CID foals varied dramatically, suggesting that the level of NSE-positive lymphocytes may be distinctive for horses with CID.

Tests for T Cell Function

• To fully understand the role of T cells in the immune response of the foals, the researchers conducted in vitro T-cell function tests. In these tests, lymphocytes from 12 normal foals didn’t show a response.
• Subsequent testing involving the intradermal injection of a specific molecule (phytohemagglutinin) resulted in visible reactions in normal foals, and skin grafting induced a significant response of mononuclear cells. Such reactions were absent or negligible in CID foals, signifying a deficiency in their immune response.

Conclusion

• The research findings are significant as they provide a comprehensive examination of CID in Arabian foals, including its effects and identifiable markers for diagnosis, establishing baseline for potential treatment approaches in the future.