CHARACTERIZATION OF DIFFERENT SOLUBLE TNF RECEPTOR (TNFR8O) DERIVATIVES - POSITIVE INFLUENCE OF THE INTRACELLULAR DOMAIN ON RECEPTOR LIGANDINTERACTION AND TNF NEUTRALIZATION CAPACITY/

Different soluble human TNFR80 derivatives, a solubilized form of the complete TNFR80, the TNFR80 extracellular domain, a secretory TNFR80 m utant (TR80TM(-)) with a deleted transmembrane region, and a TNFR80 im munoadhesin were produced in insect cells and characterized side by si de with a recombinant human TNFR60 extracellular domain with respect t o TNF binding affinity and neutralization of TNF bioactivity. The cons truct TR80TM(-) and the solubilized complete TNFR80 revealed a similar TNF binding and neutralization capacity, which was superior to the mo novalent TNFR80 extracellular domain and comparable to the bivalent TN FR80 immunoadhesin, already known as a potent TNF antagonist, Determin ation of ligand off rate constants of the various receptor constructs by surface plasmon resonance revealed a correlation of low off rates w ith a high TNF neutralization capacity, We propose that the high TNF b inding and neutralization capacity of the solubilized complete TNFR80 and TR80TM(-) in comparison with the monovalent extracellular TNR80 do main is due to a noncovalent self-aggregation of the receptors via the ir intracellular domain. This finding suggests that efficient soluble TNF antagonists can be derived from TNFR themselves without the need o f construction of TNFR Ig Fc fusion proteins.