Hemodialysis leukopenia and complement function with different dialyzers.

The relationship between leukopenia and the complement system during hemodialysis was re-examined by studying not only the in vivo effects of four different dialyzer membranes (cellulose hydrate, cuprophan, cellulose acetate, and polyacrilonitrile) on leukocyte counts and complement levels, but especially by investigating the effects of these membranes on complement function in vitro. Whereas from in vivo studies no definite conclusions could be drawn, in vitro investigations provided clear-cut information. When more sophisticated technical approaches were undertaken, it became evident that hemodialysis leukopenia has to be thought of in terms of chemotactic factor generation. In fact, a strict correlation was demonstrated between the degree of leukopenia induced by the dialyzers tested and the ability of the relative membrane to generate chemotactic activity in vitro. Moreover, the previously observed ability of polyacrilonitrile membrane to induce a decrement in complement function was due to the ability of polyacrilonitrile to adsorb complement activity and did not correspond to effective complement consumption. This finding explained why polyacrilonitrile dialysis is not accompanied by a decrease in circulating granulocytes. Taken together, our data strongly point to a pivotal role of complement system in the pathogenesis of hemodialysis leukopenia.