Failure of covalently cross-linked human IgG myeloma subclass protein to release histamine from human leukocytes.

We have examined the ability of IgG subclass antibodies to release histamine from human leukocytes using covalently cross-linked oligomers of human myeloma proteins. Purified IgG1, G2, G3, G4, (or IgE) was incubated with dimethyl suberimidate to induce cross-linking. The resulting dimers, trimers, and higher molecular weight oligomers were isolated using gel filtration columns (Sephadex G200 and Ultrogel AcA 22) connected in tandem. None of the oligomers of IgG1, G2, G3, or G4 released histamine from leukocytes of donors whose basophils released histamine when challenged with IgE dimer. Furthermore, preincubation with subclass specific oligomers did not desensitize cells to challenge with IgE dimer or to anti-IgE. We conclude that, under our experimental conditions, oligomers of human IgG myeloma subclass antibodies do not trigger histamine release nor modulate IgE-mediated reactions.