The interaction of amphotericin B with cell membrane of rat thymocytes.

Amphotericin B (AB) at micromolar concentrations increases cell membrane permeability and induced swelling of rat thymus lymphocytes. Potassium efflux is a precondition for AB to induce swelling of the cells. The rate constants for potassium loss and volume changes were proportional to the 1.24th and the 2nd power of the antibiotic concentration respectively. The reflection coefficients for nonelectrolytes with different hydrodynamic radii were determined, and the equivalent radius of the amphotericin pore in the thymocyte cell membrane was estimated to be 4.1 +/- 0.3 A at polyene concentrations varying between 2.5 mumol/l and 80 mumol/l. It is suggested that channel formation by AB in cell membranes is actually able to modulate immune responses.