Graft versus host reactions in foals with combined immunodeficiency.

This study investigates the reactions (graft versus host reactions) in foals (young horses) who have combined immunodeficiency and are given cells from non-related horses or fetuses. These reactions were observed in the form of clinical signs and lesions, with changes in blood counts and other markers indicating noticeable severity in liver lesions.

Study Objectives and Method

• This research was conducted on nine foals (young horses) who had combined immunodeficiency, a condition that affects the immune system making the organism more susceptible to infections and diseases.
• The research used hepatic (liver) and thymus cells from fetuses aged between 68 to 110 days or peripheral blood lymphocytes from non-related horses and administered them to these foals.

Observations

• Eight out of nine foals exhibited signs and developed lesions that were indicative of graft versus host reactions (reactions caused when transplanted donor cells attack the recipient’s body).
• The symptoms included diarrhea in all eight foals and ulcerative dermatitis, stomatitis, or glossitis in six out of the eight foals.
• The investigators also found histopathologic changes (abnormal cells examined under a microscope) consisting of necrosis (cell death) and lymphocyte infiltration (white blood cells entering tissue) in various tissues including the liver, skin, and alimentary tract. These changes were less frequent in lymphoid tissues.

Correlation to Blood Count Changes

• The study also observed changes in complete blood counts, plasma bilirubin concentration, and serum sorbitol dehydrogenase activity. These were compared with observed histopathologic alterations in the liver of two combined immunodeficiency foals given peripheral blood lymphocytes from unrelated donor horses.
• The researchers found that elevations in serum sorbitol dehydrogenase, an enzyme often associated with liver damage, corresponded with the onset and subsequent increase in severity of hepatic lesions in the foals, indicating a strong correlation between the two.