An ATP-activated channel is involved in mitogenic stimulation of human T lymphocytes

We investigated the effect of pharmacologic modulation of the ATP receptor on intracellular ion changes and proliferative response of human peripheral blood lymphocytes (PBLs) and purified T lymphocytes. Extracellular ATP (ATPe) triggered in these cells an increase in the cytoplasmic Ca2+ concentration ([Ca2+]i) and plasma membrane depolarization. Whereas both Ca2+ release from intracellular stores and influx across the plasma membrane were detected in the whole PBL population, only Ca2+ influx was observed in T cells. In the presence of near physiologic extracellular Na+ concentrations (125 mmol/L), Ca2+ permeability through the ATPe-gated channel was very low, suggesting a higher selectivity for monovalent over divalent cations. The selective P2Z agonist benzoylbenzoic ATP (BzATP) increased [Ca2+]i in the presence but not the absence of extracellular Ca2+ and also caused plasma membrane depolarization. The covalent blocker oxidized ATP (oATP), an inhibitor of P2X and P2Z receptors, prevented Ca2+ influx and plasma membrane depolarization, but had no effect on Ca2+ release from stores. Stimulation with ATPe alone had no significant effects on PBL 3H-thymidine incorporation. On the contrary, ATPe or BzATP had a synergistic effect on DNA synthesis stimulated by selective T-cell mitogens such as phytohemagglutinin, anti-CD3 monoclonal antibody, or allogenic PBLs (mixed lymphocyte cultures). Treatment with oATP inhibited mitogenic stimulation by these receptor-directed agents but not by the combined application of the Ca2+ ionophore ionomycin and phorbol myristate acetate. Interleukin-2 partially relieved inhibition by oATP. These results suggest that human T lymphocytes express a plasma membrane channel gated by ATPe that is involved in mitogenic stimulation.     

PROLONGED EXPRESSION OF THE c-kit RECEPTOR IN GERM CELLS OF INTERSEX FETAL TESTES

Stem cell factor (SCF) and its receptor Kit encoded by the c- kit proto-oncogene are crucial for the development and migration of primordial germ cells in rodents. The expression of Kit has been examined immunohistochemically in gonads obtained from five specimens of fetal tissues with intersex conditions which included 45,X/46,XY mosaicism; androgen insensitivity syndrome; and 46,XY/iso(p)Y mosaicism. Individuals with such disorders of sexual differentiation and Y-chromosome material carry a very high risk of developing testicular neoplasms. Fetal testicular germ cells of the intersex subjects expressed Kit at a later developmental age than controls, in which no Kit protein was detectable beyond the 15th week of gestation. This finding may indicate a disturbance of the chronology of germ cell development, or it may suggest a change of the regulation of c- kit expression in subjects with disorders of gonadal development.     

Synthesis of derivatives of phosphonic glutathione analogs*

Five analogs of S-t-butyl glutathione containing phosphonic analogs of glycine and glutamic acid were obtained by standard procedures of MA activation in solution. Simultaneous deprotection of phosphonic, carboxylic and amino groups was achieved in the silylation reaction.     

Blood donation leads to a decrease in natural killer cell activity: a study in normal blood donors and cancer patients

Transfusion-induced immunosuppression has long been known to be beneficial for organ transplantation patients, but recent retrospective studies suggest that blood transfusions may be detrimental for patients with cancer. If autologous blood is used to avoid immunosuppression, the assumption is that the procedure, involving blood donation, is immunologically neutral. In the present study, this assumption was evaluated by monitoring 33 normal blood donors and 16 colorectal cancer patients before and after donation of 1 (500 mL) and 2 units of blood, respectively. The cancer patients belonged to the autologous arm of a randomized trial in which the effects of allogeneic versus autologous blood on cancer prognosis were studied. The patients donated 2 units of blood with an interval of 3 to 4 days between donations. Flow cytometric analysis revealed that blood donation by normal donors and cancer patients had no effect on the proportion of B, T, and natural killer (NK) cells. Only the total number of lymphocytes was significantly decreased in the normal donors on Day 12 after donation. Blood donation had no significant effect on T-cell function assessed by phytohemagglutinin stimulation in normal donors or in cancer patients donating 2 units of blood. A significant depression of NK cell function (88% and 74% of predonation levels) was observed in normal donors on Days 2 and 5 after donation; on Day 12, the activity was again normal. Colorectal cancer patients had a significantly depressed NK cell activity (54% of predonation activity) on Day 12 after the first donation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surprising Pharmacological Activity of Analogues Designed by Substitution of Position 3 in Arginine Vasopressin (AVP) and 8-D-Arginine Vasopressin with l-2-Naphthylalanine

In an attempt to develop more active and selective analogues of arginine vasopressin (AVP), two peptides have been designed, synthesized and tested for vasopressor (V₁-receptors) and antidiuretic (V₂-receptors) activities. We also estimated the uterotonic and anti-uterotonic activities of these compounds in-vitro. The first peptide, [(l -2-Nal)³] AVP is a highly active V₂-agonist. The second analogue, [(l -2-Nal)³, (d -Arg)⁸]VP is among the most potent antagonists of the vasopressor response to AVP. Moreover, it is the first V₁-antagonist devoid of anti-uterotonic activity. High antipressor potency of the second peptide was achieved without modification of position 1.     

PLASMA TESTOSTERONE AND ANDROSTENEDIONE LEVELS DURING MONITORED INDUCTION OF OVULATION IN INFERTILE WOMEN WITH 'SIMPLE' AMENORRHOEA AND WITH THE POLYCYSTIC OVARY SYNDROME

Twenty-seven infertile patients with ‘simple’ amenorrhoea-oligomenorrhoea and eighteen with the polycystic ovary (PCO) syndrome were treated for induction of ovulation with clomiphene, human menopausal gonadotrophin and human chorionic gonadotrophin. The treatment was monitored by plasma oestradiol, testosterone, andfostenedione and progesterone estimation. Women with PCO had significantly higher plasma androgen levels than women with ‘simple’ amenorrhoea (P < 0.01 to P < 0.001) both before treatment and during induction of ovulation. When ovulation was induced the pregnancy rate for women with the PCO syndrome with elevated androgens was 21% while for those with uncomplicated amenorrhoea it was 75%. It is concluded that high levels of circulating androgens might be a factor preventing conception in some patients in whom ovulation is apparently successfully induced.