IMMUNOHISTOCHEMICAL STUDY OF CYTOCHROME B5 IN HUMAN ADRENAL-GLAND ANDIN ADRENOCORTICAL ADENOMAS FROM PATIENTS WITH CUSHINGS-SYNDROME

Cytochrome b5, a component of the electron transfer system increases t he relative activity of 17,20-lyase to 17 alpha-hydroxylase of P450c17 in vitro. In the present study, immunohistochemical analysis of cytoc hrome b5 was performed in the human adrenal gland and in adrenocortica l adenomas from patients with Cushing's syndrome. In the human adrenal gland, cytochrome b5 was stained in all three adrenocortical layers b ut the staining was most remarkable in the zona reticularis. All of th e adenomas were composed mainly of compact cells, which exhibited immu noreactive staining for cytochrome b5 as well as for P450c17 and 3 bet a-hydroxysteroid dehydrogenase (3 beta-HSD). The distribution of b5 in the adenomas was correlated with that of P450c17 rather than with tha t of 3 beta-HSD. The immunoreactive staining for cytochrome b5 appeare d to be more prominent in the two adenomas that produced relatively hi gh concentrations of adrenal androgens than in adenomas that produced low concentrations of adrenal androgens. These results immunohistochem ically support the functional association of b5 with androgen producti on through interaction with P450c17 and the previous finding that high er concentrations of cytochrome b5 are associated with greater product ion of adrenal androgens in adrenocortical adenomas from patients with Cushing's syndrome.