IgG subclass deficiency in acute myeloid leukemia.

Serum IgG subclass levels were measured using a competitive indirect immunoenzymatic assay with monoclonal antibodies in 22 acute myeloid leukemia patients at presentation and prior to specific therapy. Three patients had moderate IgG1 deficiency and 1 moderate IgG3 deficiency. Two of the three IgG1 deficient patients (and only one other) failed to respond to induction chemotherapy and the third died of bone marrow aplasia during induction.