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Molecular structure alteration of IgG increased anticomplementary activity of intravenous immunoglobulin
Aim:
To study the cause of anticomplementary activities (ACA) of intravenous immunoglobulins (IVIG).
Methods:
ACA were determined by two assays (limit test and 100CH50 test), distributions of IgG molecular size (polymer, dimer, monomer and fragment) by HPLC, IgG subclasses and IgA contents by radial immunodiffusion, prekallikrein activator (PKA) and kallikrein (KK) activities by chromogenic assay, potency of antibody against hepatitis B surface antigen (Anti-HBs) by enzyme-linked immunosorbent assay (ELISA).
Results:
The two ACA assays showed good correlation. However, ACA levels were not associated with distributions of IgG molecular size, IgG subclasses and IgA contents, PKA and KK activities. After heating incubation, ACA levels increased markedly and Anti-HBs decreased notably, distributions of IgG molecular size remained relatively constant.
Conclusion:
Molecular structure alteration of IgG increased spontaneous complement activation of IVIG.