Cortisol metabolism in lymphocytes from cancer-bearing patients

Pseudoaromatase in circulating lymphocytes

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.

The effect of fatty acids on the vulnerability of lymphocytes to cortisol

We have shown previously that cortisol-sensitive lymphocytes (thymocytes) have a much lower capacity than cortisol-resistant cells to catabolize cortisol and that linoleic acid inhibits the catabolism of cortisol by lymphocytes and modulates the sensitivity of lymphocytes to cortisol. In the present study, we attempted to see whether other fatty acids are inhibitory and if inhibition of cortisol catabolism by lymphocytes indicates a change in resistance of the cells to cortisol. Measuring the effect of fatty acids on cortisol catabolism by lymphocytes indicated that the polyunsaturated fatty acids, linoleate, arachidonate, and eicosapentaenoic, inhibit cortisol catabolism by lymphocytes. Using prostaglandin PGE2 and indomethacin as a blocker of prostaglandin formation, we observed that the effect of the polyunsaturated fatty acids was not due to the formation of prostaglandins. Examining the effect of fatty acids on the vulnerability of lymphocytes to cortisol, we noted that saturated fatty acids had no significant effect, whereas the aforementioned polyunsaturated fatty acids make lymphocytes more sensitive to cortisol.

Effect of antiglucocorticoids on dexamethasone-induced inhibition of uridine incorporation and cell lysis in isolated mouse thymocytes

We have compared in isolated mouse thymocytes the action of progesterone, cortexolone, DXH (a 17-beta carboxamide derivative of dexamethasone) and RU 38486 (a new antiglucocorticoid molecule), on dexamethasone-induced inhibition of uridine incorporation and cell lysis, with the affinities of these drugs for glucocorticoid receptors. Our results show that progesterone, cortexolone and DXH which possess similar affinities for glucocorticoid receptors may exhibit variable, weak agonist and antagonist activities according to the parameter studied. RU 38486 was a potent competitor of dexamethasone and was able, when present in a 10-fold excess, to counteract almost completely the inhibitory action as well as the lytic action of 5 X 10(-8) M dexamethasone. This compound which exerts almost no agonist activity may therefore represent a useful tool to investigate the mode of action of antiglucocorticoids.

The influence of homologous plasma and fetal calf serum on human lymphocytic cortisol metabolism

The influence of a) tissue culture medium (RPMI), b) homologous plasma (HP), and c) fetal calf serum (FCS) on lymphocytic cortisol metabolism was compared to that of phosphate buffered saline alone. RPMI was found to enhance the conversion rate 1.71 times, whereas HP and FCS enhanced it about 3.2 times. Raising the temperature of the HP and FCS to 100 degrees C before incubation reduced the enhancing effect to the level of that obtained with RPMI.

Metabolism of cortisol by human thrombocytes

A study was made in order to see whether human thrombocytes are capable to metabolize cortisol. Known concentrations of thrombocytes were incubated with 1.23H-cortisol and the products isolated and identified by t.l.c., paper chromatography, and derivations. Two metabolites were found to be produced by thrombocytes: 20beta-hydroxycortisol and tetrahydrocortisol. The enzymatic nature of the reactions was proved by (1) heat treatment (2) finding out NADPH to be a specific cofactor and (3) the dependence of the activity on the number of thrombocytes in suspensions.