T-kinin and T-kininogen--an historical overview.

Abstract

It is well known that bradykinin liberation of trypsin from mammalian plasmas reflects the levels of high (HMW) and low molecular weight (LMW) kininogens of the plasma. Consequently the addition of trypsin to plasma is classically used to measure the total kininogen content of plasma of all species1,2 by measuring the liberation of kinin. Kinin is generally measured by bioassay or by radioimmunoassay. It is important to understand that until 1983, when our laboratory on HPLC separation of kinins,3 investigators could not differentiate clearly between bradykinin and its analogs by the bioassay or radioimmunoassay techniques. Many assumptions were made particularly in terms that HMW and LMW kininogens were the important proteins liberating kinins in all species. One piece of evidence that seemed to indicate that a third kininogen other than LMW or HMW was present in some fluids was the isolation of leukokininogen from human ascites fluid by Roffman and Greenbaum.4 Leukokininogen was a poor substrate for kallikreins but did liberate a kinin (termed leukokinin by our laboratory) by either cathepsin D or trypsin. Hiroshi Okamoto joined our laboratory in 1982 and began a study on the relative concentration of leukokininogen compared to HMW and LMW kininogens in human, rabbit and rat plasmas. In order to obtain the total kininogen content, the classic concentration of 0.1 mg trypsin added to 1 ml of plasma was initially used.