Effect of methylxanthines,cytochalasin B and FMLP on neutrophil filterability in a constant flow system

Abstract

Granulocyte rigidity was estimated from the pressure-time curves generated by constant flow through Hemafil filters. The curves were used to deduce β, a factor relating the flow resistance presented by a cell to that of suspending medium. The cells were prepared in two buffer systems, one which allowed partial stimulation as evidenced by pseudopod formation and one which did not. β for cells activated by buffer alone was twice that of resting (pseudopod-free) cells, while activation of resting cells by FMLP at ${10}^{-7}$ M raised β ten-fold. In 10 mM pentoxifylline (PTX) β of buffer- or FMLP-activated cells fell to a level similar to that of resting cells, but PTX had no effect on resting cells. Cytochalasin B (CB) lowered β more than PTX. The effect of other methylxanthines (HWA 285 and HWA 448) was similar to PTX. β was found to be shear stress dependent, and differences between activated and PTX-treated cells were magnified at lower pressures. The behavior of granulocytes in this simple model system suggests that activation might lead to significant increases in the precapillary resistance, and that treatment with pharmacological agents might prevent this.