Tehran University Medical Journal (Jul 2005)
The Comparison Of Immunoassay And Bioassay Methods To Determine TNF- In Supernatants Of Platelet Concentrates
Abstract
Background: Tumor necrosis factor alpha (TNF-) is a major mediator of inflammatory responses and also plays a role in Febrile non-hemolytic reactions (FNHRs) after platelet concentrates (PCs) injection. It is thought contaminating WBCs are the source of these cytokine so inactivating or decreasing of these WBCs will be effective to decline of the cytokines. Due to difference results between different methods for TNF measurement, in this study we compared Immunoassay and Bioassay methods to determine TNF- in supernatants of PCs. Materials and Methods: TNF- was measured by ELISA (Immunoassay) and by the L929 cytotoxicity Bioassay in supernatant of random donor PCs (RD-PC) prepared by platelet rich plasma (PRP). These platelet concentrates were divided in 4 groups: 1-unfiltered , non-irradiated RD-PCs (N=13) 2-unfiltered and -irradiated RD-PCs (N=16) 3-filtered , non-irradiated RD-PCs (N=14) 4-filtered and -irradiated RD-PCs (N=11) Results: Our results showed: •TNF-  was increased (by ELISA) in unfiltered non-irradiated units during storage but not in -irradiated and filtered RD-PCs in day 3. Compared to unfiltered PCs in filtered units, pre-storage filtration and irradiation prevented a rise in the TNF-  in day 3 of storage. •There was no correlation between ELISA and the cytotoxicity L929 bioassay . Conclusion: It has been previously reported that different quantitative results can be obtained when TNF alpha is measured in biological fluids by Bioassay and Immunoassay. This is thought to be related to the presence of antigenic forms of TNF alpha that cannot be detected by bioassay, such as complexes with soluble receptors (sTNF-R) or TNF alpha monomers.
