NO EFFECT OF A NEW 2ND-GENERATION B-DOMAIN-DELETED RECOMBINANT PRODUCT ON LYMPHOCYTE-TRANSFORMATION IN-VITRO - A STUDY OF PLASMA-DERIVED AND RECOMBINANT PRODUCTS

Immunomodulatory effects of various factor VIII and factor IX clotting factor concentrates (CFCs) and of albumin were evaluated by a sensiti ve assay measuring the incorporation of H-3-thymidine in phytohaemaggl utinin-stimulated lymphocytes in the presence of monodansylthiacadaver ine. In contrast to previous findings by others, we found lymphocyte t ransformation to be inhibited by all plasma-derived factor VIII concen trates at concentrations of 0.02, 0.2 and 2.0 IU/ml, including those p urified by monoclonal antibodies (P<0.05). Kryobulin TIM3 had the most pronounced effect. In addition, three plasma-derived human albumin pr eparations exerted a similar inhibitory effect as the factor Vm concen trates, whereas the corresponding plasma-derived factor IX concentrate s only manifested minor immunomodulatory effects. Of the recombinant p reparations, only Recombinate exerted an inhibitory effect at 0.02 and 0.2 IU/ml, whereas both Kogenate and Recombinate decreased H-3-thymid ine incorporation at 2.0 IU/ml (P=0.01). No immunomodulatory effect at all was observed with r-VIII SQ, a new B-domain-deleted recombinant f actor VIII preparation free from added albumin. The significance of th is finding regarding immunological side-effects including inhibitor de velopment remains to be evaluated, but this second-generation recombin ant product opens up new and interesting perspectives yet to be explor ed.