Primers of contact system activity in asthmatic patients and contrast material reactors.

An accelerated prekallikrein transformation is present at 4 degrees C in plasmas obtained from asthmatic patients (asthma plasmas) and in prereaction plasmas from contrast material (CM) reactors. Preliminary data show that (1) higher levels of alpha 2-macroglobulin bound kallikrein (alpha 2M-KK) may be found in asthma plasmas and pre-contrast medium reactor plasmas in comparison with control plasmas. In the asthma plasmas, these differences approach, but do not quite attain, significance; (2) complexes of alpha 2M-KK potentiate prekallikrein activation in buffer (BA) and dextran sulfate activation (DSA) assays; and (3) polybrene (factor XII inhibitor) induces an early blockage in the production of kallikrein activity in BA and DSA, indicating the presence in these plasmas of cryptic surfaces with a function analogous to dextran sulfate. These results indicate that, in asthma and probably in CM reactors plasmas, cryptic surfaces and alpha 2M-KK may each contribute to contact system activity induced at 4 degrees C.