Immunohistochemical localization of carbonic anhydrase I and II in eccrine sweat glands from control subjects and patients with cystic fibrosis.

Isozymes of carbonic anhydrase (CA) were localized immunohistochemically by the immunoglobulin-peroxidase bridge technique on fixed paraffin sections of human eccrine sweat glands. Low-activity CA I was identified in the cytoplasm of the myoepithelial cells in the secretory coil and in the luminal and basal cells of both the coiled and straight segments of the duct. High-activity CA II was found in the cytoplasm of clear cells of the secretory coil. Although evidence has suggested that CA activity is altered in cystic fibrosis (CF), the present immunohistochemical comparison of CF sweat glands revealed a distribution of and, semiquantitatively, a prevalence of CA isozymes identical to those of normal sweat glands. Abnormal enzyme activity cannot be ruled out, however, on the basis of immunocytochemical staining which depends solely on the antigenic properties of CA.