The new bioaffinity membranes comprise mammalian blood and tissue cells immobilized in the polymer matrix. The method of immobilization does not assume the retention of physiological and enzymatic activity of immobilized cells, but it ensures the safety of cellular membrane receptors that are used as specific ligands. Macroporous polymer carriers based on polyacrylonitrile maintain the accessibility of the cellular receptors for all blood plasma components including immunoglobulins and viral particles. The sorption capacity of membranes with respect to model substances in a batchwise technique is evaluated. Although the results are of a preliminary nature, the membranes may be used in crossflow modules for selective blood plasma correction of endogenous substances.