Membrane viscosity of lymphocytes and influence of phytohemagglutinin.

The research article focuses on measuring the membrane viscosity of peripheral blood lymphocytes from three animal types (equine, bovine, and canine), and analyzing the possible effects of a stimulant called phytohemagglutinin-P on this viscosity.

Measurement of Membrane Viscosity

• The study uses a method known as the time-resolved fluorescence depolarization technique to gauge the viscosity of the membrane of peripheral blood lymphocytes, which are a certain type of white blood cells.
• The fluorescence depolarization technique utilizes a fluorescence dye named 1, 6-diphenyl-1,3,5-hexatriene (DPH), which measures how photons move within the membrane and reveals its viscosity.
• The viscosity was different for each animal: 0.55 poise for equine, 0.59 poise for bovine, and 0.50 poise for canine peripheral blood lymphocytes.

Comparison with Steady-state Anisotropies and Order Parameters

• The calculated viscosity values were then compared with steady-state anisotropies and order parameters. These were measured through a technique called electron spin resonance (ESR), using 5-doxyl stearic acid.
• The researchers observed that the viscosity was directly related to the anisotropies and the order parameters–the higher the viscosity, the higher these two parameters.

The Role of Phytohemagglutinin-P

• The research also investigated the effect of a stimulant named phytohemagglutinin-P (PHA) on the lymphocytes’ membrane fluidity.
• The researchers analyzed the fluid property of the lymphocytes’ membranes once they were exposed to PHA, using steady-state fluorescence anisotropy and electron spin resonance.
• Contrary to what might be expected, the researchers noted little change in the membrane’s fluidity even with the presence of PHA. The results suggest that the process of PHA activation for these lymphocytes does not significantly increase membrane fluidity or accelerate the diffusion velocity of receptors in the membrane.