Activity of adenosine deaminase and purine nucleoside phosphorylase in erythrocytes and lymphocytes of man, horse and cattle.

This research paper explores the activity of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) in the erythrocytes and lymphocytes of humans, horses, and cattle. Differences in enzyme activity were observed, with bovine hemolysates exhibiting lower activity and horse hemolysates showing virtually no activity.

Overview of Activities of ADA and PNP

• The study started by measuring the activities of ADA and PNP in erythrocytes (red blood cells) and lymphocytes (white blood cells) in humans, horses, and cattle.
• These enzymes are crucial as they play key roles in the degradation of purine nucleosides, which are crucial components of DNA and RNA.

Differences in Enzyme Activities in Bovine and Horse

• The research found that in bovine, or cattle hemolysates, the activities of both enzymes were significantly lower when compared with those in human hemolysates.
• In stark contrast, in horse hemolysates, both enzyme activities were virtually non-existent.

Enzyme Activities in Intact and Sonicated Lymphocytes

• The activities of both enzymes were consistently found to be around 50% lower in intact lymphocytes as compared to sonicated lymphocytes – those that have been disrupted by sound waves.
• This finding indicates that the uptake of nucleosides could be the rate-limiting step for both enzymes in intact lymphocytes, which means that the speed at which these cells absorb nucleosides is potentially controlling the rate of enzyme activity.

ADA Activity in Horse Lymphocytes

• The activity of ADA in horse lymphocytes was found to be similar to the activity level in the lymphocytes of patients with severe combined immunodeficiency (SCID) associated with ADA deficiency.
• Patients with SCID lack functional T and B cells – significant elements of the immune system – complicating the immune response. The similarity in ADA levels between horses and these patients might have interesting implications for veterinary and comparative medicine research.