The role of plasma in the transfer of Escherichia coli cytokine-inducing substances across high-flux cellulosic membranes.

It has been previously reported that the presence of plasma in the blood side compartment of cellulosic membranes enhances the transfer of cytokine-inducing substance (CIS) present in the dialysate compartment. This apparent enhancement could either be a result of (1) improved membrane permeability to CIS, (2) transfer of plasma components to the dialysate compartment thereby causing dissaggregation of CIS with subsequent backtransfer to the blood compartment, or (3) improved detection of transferred CIS resulting from carryover of plasma from the blood compartment to the mononuclear cell incubation step. An in vitro dialysis model was used to determine which of the above mechanisms were involved in this phenomenon. Results showed that enhanced detection of CIS could not be attributed to improved detection resulting from carryover plasma. Both addition of plasma to the dialysate compartment of pre-exposure of membranes to plasma resulted in enhanced transfer of CIS in a fashion similar to that seen when plasma was added to the blood compartment. These observations suggest that the transfer of Escherichia coli culture filtrate-derived CIS across cellulosic membranes is enhanced on exposure to 10% plasma because of alterations in the permselectivity of the membrane.