Mayumi Imoto, Toshinori Kamisako
The low molecular weight ɤ chain was also found to be a half-molecular IgG with a CH2 domain deletion, as inferred from the reactivity of the antibody.
BACKGROUND: Half-molecule immunoglobulins are low-molecular-weight abnormal immunoglobulins composed of one defective heavy chain (H chain) and one light chain (L chain) of normal molecular weight.
METHODS: The molecular weight of the low molecular weight IgG was determined using SDS-PAGE and immunoblotting with patient serum. To prove that the low molecular weight IgGs were L-chain and deficient γ-chain, SDS-PAGE was used to cut out and reduce the entire gel of unreduced, migrated proteins. Then, a second SDS-PAGE was run.
RESULTS: The low molecular weight IgG component was found to consist of normal molecular weight κ chains (32 and 29 kDa) and defective γ chains (37 and 38 kDa). Low molecular weight IgG did not react with anti-γ-CH2 domain antibodies.
CONCLUSIONS: The low molecular weight ɤ chain was also found to be a half-molecular IgG with a CH2 domain deletion, as inferred from the reactivity of the antibody.