Preparation of soluble apolipoproteins A-I, B, and C-II by a chromatofocusing column method, and evaluation of their concentrations in serum in pulmonary disease

Abstract

A chromatofocusing column method for isolating ApoB is described. LDL is first isolated by sequential ultracentrifugation and delipidated with n-butanol/diisopropyl ether. Chromatofocusing of ApoLDL yielded a large ApoB peak at pI 5.0-5.3. ApoA-I and ApoC-II were prepared analogously, with HDL and VLDL as the source of apoprotein. Antisera were raised in rabbits, and electroimmunoassay techniques were used for determination. ApoB was water-soluble after chromatofocusing. Intra-assay precision (CV) was 4.7% for ApoA-I, 7.8% for ApoB in the 'rocket' electrophoresis. Interassay precision (CV) was 6% for ApoA-I and 8% for ApoB. Apolipoprotein concentrations were measured in subjects who had undergone lung resection and patients with obstructive pulmonary disease. After lung resection, the concentration of ApoA-I in serum was significantly decreased (p < 0.001) and that of ApoB significantly increased (p < 0.001) as compared with controls. The ApoA-I/ApoB ratio was significantly lower in the lung-resection group. ApoA-I and ApoB concentrations were unchanged in chronic obstructive pulmonary disease. ApoC-II concentrations in each group were similar to those for control subjects. Of the lipids, values for total cholesterol were above normal after lung resection (p < 0.002), as were those for triglycerides (p < 0.02).