Immunohistochemical distribution of adult T-cell leukemia-derived factor/thioredoxin in epithelial components of normal and pathologic human skin conditions.

Tissues from normal human skin and various skin diseases were studied with the immunoperoxidase technique using an antibody to adult T-cell leukemia-derived factor (ADF), a homologue of human thioredoxin. Normal human skin showed positive immunostaining for ADF/thioredoxin in the outer root sheath of hair follicle, sebaceous glands, and secreting components of apocrine and eccrine sweat units, but not in the unexposed interfollicular epidermis and other parts of both hair follicles and the sweat units. Immunoreactivity of benign skin tumors gave similar distribution to their normal counterparts; trichilemmal cyst, nevus sebaceus, senile sebaceous hyperplasia, and mixed cell tumor were positive for immunostaining, whereas epidermal cyst and pilomatricoma were not. No immunoreactivity was detected in malignant skin tumors such as basal cell carcinoma and poorly differentiated squamous cell carcinoma. Solar keratosis, well-differentiated squamous cell carcinoma, some of metastatic lesions of squamous cell carcinoma, and extramammary Paget's disease reacted with the antibody. These immunoreactivities reflected numerous functions of thioredoxin in higher organisms. Our findings suggest that the expression of ADF/thioredoxin in both normal and abnormal human skin is related to epithelial cell differentiation.