Comparison of the carbohydrate composition of alpha 2-macroglobulin from patients with cystic fibrosis and normal controls.

The putative involvement of alpha 2-macroglobulin (alpha 2M) in the pathogenesis of cystic fibrosis has long been a subject of controversy. Previous reports have indicated that there are alterations in the carbohydrate moieties of alpha 2M in the disease. In the present study the carbohydrate composition of alpha 2M isolated from the plasma of six patients with CF was compared to that of alpha 2M from six age- and sex-matched normal controls. The carbohydrate composition of CF alpha 2M expressed as mean mumol carbohydrate +/- SD per 100 mg protein was: fucose 0.70 +/- 0.12; mannose 14.07 +/- 1.31; galactose 6.72 +/- 0.65; glucosamine 15.38 +/- 1.59; sialic acid 5.52 +/- 0.33 while that of normal control alpha 2M was: fucose 0.69 +/- 0.11; mannose 14.42 +/- 1.21; galactose 6.91 +/- 0.52; glucosamine 16.13 +/- 1.77; sialic acid 5.58 +/- 0.31. Therefore, contrary to previous reports, this paper demonstrates that there is no difference in the carbohydrate composition of alpha 2M in cystic fibrosis.