Concentration of nucleotides and deoxynucleotides in peripheral and phytohemagglutinin-stimulated mammalian lymphocytes. Effects of adenosine and deoxyadenosine.

This study investigates the concentrations of purine and pyrimidine ribonucleotides in the lymphocytes of several mammals and consider how these concentrations are affected by substances such as adenosine and deoxyadenosine. The researchers discovered that the ATP concentration was highest in all species, but variations were observed across different mammals. The study also revealed that ATP concentrations decreased during culturing with or without phytohemagglutinin.

Methodology

• The researchers used high-performance liquid chromatography (HPLC) to measure concentrations of purine and pyrimidine ribonucleotides in the lymphocytes of humans, horses, pigs, sheep, and rat thymocytes.
• The ATP concentration was also measured with a luciferin-luciferase assay in the lymphocytes of humans, horses, and pigs.
• During the culture period, both with and without phytohemagglutinin, ATP concentrations were monitored and found to decrease.
• The team used a DNA polymerase assay to measure TTP and dATP concentrations, which revealed that the concentration of TTP increased in a phytohemagglutinin-induced environment for all three species, while dATP concentration increased only in humans.

Findings

• When lymphocytes were cultured in the presence of adenosine or deoxyadenosine, monitoring found an increase in the ATP concentration in porcine and equine lymphocytes but not in human lymphocytes.
• Of note, adenosine and deoxyadenosine did not affect the TTP concentration.
• In certain conditions with EHNA (an adenosine deaminase inhibitor), deoxyadenosine decreased the ATP concentration only in human lymphocytes, but increased it in other situations as well as in equine and porcine lymphocytes.
• The introduction of deoxyadenosine in conjunction with EHNA boosted the dATP concentration by 3-fold in human, 10-fold in equine and 9-fold in porcine lymphocytes, whilst significantly reducing thymidine incorporation.
• However, deoxyadenosine, without EHNA, increased the dATP concentration by 2-5 fold, decreased thymidine incorporation in human and equine lymphocytes but stimulated the incorporation in porcine lymphocytes by about 5-fold.

Conclusion

• The researchers concluded that the accumulation of dATP is not always associated with the inhibition of cell proliferation, challenging a common belief on the relationship between these biochemical factors.