Functional assessment of pathogenic IgG subclasses in chronic autoimmune urticaria

Purification of IgG subclasses from patients with chronic urticaria demonstrates functional antibody in IgG1 and IgG3 and occasionally IgG4. Nonfunctional antibody within IgG2 plus nonfunctional antibody mixed with functional antibody within IgG1, IgG3, and IgG4 and effects of complement are responsible for a lack of correlation of histamine release with binding assays even if subclass-specific.