Suppressor lymphocyte activity in normal and immunodeficient horses.

Area of Science:

• Immunology
• Veterinary Science
• Cell Biology

Background:

• Mixed lymphocyte reactions (MLRs) are crucial for assessing cellular immune responses.
• Understanding lymphocyte function is key to diagnosing and treating immune deficiencies in horses.

Purpose of the Study:

• To investigate the presence and characteristics of Concanavalin A (Con A)-induced suppressor lymphocytes in horses.
• To determine the role of these suppressor cells in various equine immune states.

Main Methods:

• Equine lymphocytes were incubated with Con A and isolated using BSA density gradients.
• The ability of these isolated lymphocytes to suppress MLRs was assessed.
• Radiosensitivity of suppressor lymphocytes was evaluated.
• Lymphocyte populations from different tissues and horses with specific immune conditions were analyzed.

Main Results:

• Con A-treated lymphocytes suppressed MLRs in a dose-dependent manner.
• Suppressor lymphocytes were radiosensitive, even post-Con A incubation.
• Consistent suppressor activity was observed in peripheral blood mononuclear leukocytes from normal horses.
• Suppressor activity was absent in thymus cells and variable in lymph node cells.
• Suppressor lymphocytes were present in horses with selective IgM deficiency and lymphosarcoma.
• Suppressor cells were not detected in most horses with severe combined immunodeficiency.

Conclusions:

• Equine lymphocytes can develop Con A-induced suppressor activity, primarily from peripheral blood.
• These suppressor cells are radiosensitive and their presence varies with immune status and tissue origin.
• The findings suggest a role for these suppressor lymphocytes in equine immune regulation and disease states.