Determination of IgG Subclasses in Patients With Pemphigus With Active Disease and in Remission

• IgG subclasses were determined in perilesional skin of 13 patients with pemphigus with active disease and of 14 patients in a state of clinical remission. Using indirect immunofluorescence technique, frozen sections were incubated with mouse monoclonal antihuman IgG₁, IgG₂, IgG₃, and IgG₄ followed by a second incubation with fluorescein isothiocyanate-conjugated goat antimouse IgG. The results showed that among patients with active disease, IgG₁ was found in all of them and IgG₄ in 85%, while IgG₂ and IgG₃ were found in 54% and 77%, respectively. For patients in remission the most common subclass was IgG₄ in 79% of patients, and in a decreased order IgG₁, 50%; IgG₃, 29%; and IgG₂, 14%. It appears that IgG₁ and IgG₄ are predominant among patients with active lesions. IgG₁ seems to be the most sensitive indicator for activity of the disease. IgG₄, normally found in the lowest concentration in human serum, is the most common subclass in patients who are in remission. IgG₃ and C3 may have a predictive value for remission.

(Arch Dermatol. 1989;125:787-790)