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Abstract

Following reports by Shapira et al. that α₂Macro-globulin (α₂M) is abnormal in cystic fibrosis (CF), the author set out to examine the properties of α₂M isolated from the plasma of children with CF and from the plasma of age/sex matched controls. To do so, a technique capable of isolating pure, physiologically "active" α₂M from small plasma samples had to be developed. By a two-step chromatographic technique, involving Cibacron Blue Sepharose chromatography and immuno-adsorption, the author was able to isolate "active" CF and control α₂M of at least 98 percent purity from 5 ml of plasma, regardless of plasma haptoglobin type. Having accomplished this, comparative studies of CF and control α₂M were undertaken. Four parameters were investigated: (1) the molar protease binding of α₂M (2) the interaction of α₂M -bovine cationic trypsin (BCT) complexes with the low molecular weight substrate BAEE, (3) the stability of formed α₂M-BCT complexes, and (4) the subunit structure of α₂M. Contrary to the reports of Shapira and his colleagues, this author found no differences between the subunit structure of CF and control α₂M nor between the abilities of CF and control α₂M to interact with BCT. Based upon these findings, the author believes that no firm evidence exists to implicate an α₂M defect in the pathogenesis of cystic fibrosis.