Pseudoaromatase in circulating lymphocytes.

ABSTRACT

A variety of data suggesting a relationship between estrogens and the immune system prompted a study of aromatase activity in blood lymphocytes. A tritiated water aromatase assay detected activity of 1.9 to 25.1 pmol/g protein/h in 14 samples of human lymphocytes. To confirm these results, additional tritiated water and product isolation assays were performed on a large pool of lymphocytes obtained from 4 U of blood. An assay using [1 beta-3H]androstenedione generated high apparent aromatase activity, 943 pmol/g protein/h, but this activity could not be blocked by the aromatase inhibitor, CGS 16949A. More direct methods of evaluation yielded the following results: (1) PCR demonstrated no aromatase mRNA production in lymphocytes; (2) direct product isolation using [1,2,6,7-3H]androstenedione yielded insignificant production of estrone and estradiol; (3) immunostaining of fixed lymphocyte smears with a polyclonal antibody to aromatase yielded equivocal results. These data suggest the presence of pseudoaromatase in blood lymphocytes. Since circulating lymphocyte pseudoaromatase levels can be correlated with various factors in patients, such as age, menopausal status, and glucose ingestion, further studies of this activity are warranted.