LDH結合性免疫グロブリン3症例の生化学的検討

抄録

Biochemical properties of LDH linked immunoglobulin complexes found in sera of three cases (IgG-κ, IgA-κ, IgG-κ, λ) were studied. The complexes were completely dissociated by gel filtration at pH 3.0 and the dissociated LDH with normal molecular size showed a normal zymogram. When the dissociated immunoglobulins were incubated with each of the LDH isozymes (LDH_1-5), the two IgG type immunoglobulins recombined with all isozymes, but the IgA type immnoglobulin showed limited combination with only LDH_{2, 3, 4} fractions, indicating a difference in binding specificity between IgG and IgA.
Subclass specificity tested in two IgG types was not detected by Protein A affinity chromatography. The binding site of IgG was confirmed to exist on the Fab portion by the method of papain digestion. 5'-AMP-Sepharose 4 B affinity chromatography revealed different affinity between LDH linked IgG (broad pattern) and LDH linked IgA (extra band). This finding suggests the presence of conformational heterogeneity.