Inter-alpha-trypsin inhibitor (ITI): use of new antisera for qualitative studies and discrete quantitation of ITI and its derivatives.

Inter-alpha-trypsin inhibitor (ITI) is a human protease inhibitor characterized by its coexistence with several physiological derivatives displaying immunological cross-reactivity when analyzed in plasma with usual anti-ITI antisera. Taking advantage of the presence in urine of a particular ITI derivative, antisera with restricted specificity for either ITI or its derivatives could be prepared. Some applications of these new reagents are given, including qualitative studies and discrete quantitation--by electroimmunoassay--of ITI and ITI derivatives. The procedures herein described should prove useful for qualitative and quantitative analysis to investigators dealing with mixtures of antigenically related proteins.