ABSTRACT
The protein phosphatase activity of peripheral blood T lymphocytes (PBLs) was examined to quantify the contribution of calcineurin and other members of the family of serine/threonine protein phosphatases. Using selective phosphatase inhibitors, the fractional phosphatase activities of calcineurin, protein phosphatases 1 (PP1), 2A (PP2A), and 2C (PP2C) were determined. Okadaic acid was used to inhibit the activity of both PP1 and PP2A while cyclosporin A/cyclophilin or trifluoperazine were used as a specific inhibitors of the calmodulin-dependent phosphatase calcineurin. Using a [32P]labeled 19-residue phosphopeptide substrate, RII peptide, it was found that PP1 and PP2A comprise the majority of the total phosphatase activity in PBLs with okadaic acid inhibiting 80% of the phosphatase activity. The remaining 20% of the phosphatase activity can be attributed primarily to calcineurin since it was Ca2+ dependent, sensitive to inhibition by the calmodulin antagonist trifluoperazine, and inhibited by the complex of cyclosporin A (CsA) and cyclophilin. These results indicate that PBL extracts contain little PP2C activity. In addition, PBLs treated with CsA had measurably lower calcineurin activity in cell lysates. The measurement of calcineurin activity may provide a useful means of assessing the extent of immunosuppression during drug therapy.
Subject(s)
Calmodulin-Binding Proteins/blood , Phosphoprotein Phosphatases/blood , T-Lymphocytes/enzymology , Amino Acid Sequence , Calcineurin , Calmodulin-Binding Proteins/antagonists & inhibitors , Cyclosporine/pharmacology , Drug Resistance , Enzyme Inhibitors/pharmacology , Ethers, Cyclic , Humans , Immunosuppressive Agents/pharmacology , Molecular Sequence Data , Okadaic Acid , Phosphoprotein Phosphatases/antagonists & inhibitors , Trifluoperazine/pharmacologyABSTRACT
OBJECTIVE: To evaluate the clinical impact of essential thrombocythemia on the outcome of pregnancy or vice versa. DESIGN: A retrospective study. SETTING: All patients were seen at our tertiary referral center, and most were followed up by their local physicians. PATIENTS: From 1975 through 1991, 73 women younger than 50 years with essential thrombocythemia were seen at our institution. All patients were followed up through patient or physician contact. A detailed obstetric history, including peripartum complications and management, was obtained. RESULTS: Among the 73 women, 34 pregnancies occurred in 18 patients. There were two uncomplicated elective abortions and one ectopic pregnancy. Of the 31 other pregnancies, 17 (55%) resulted in live birth and 14 (45%) ended in spontaneous abortion (all but two in the first trimester). Abortion could not be predicted from history of disease complications before or during pregnancy or by the presence or absence of specific therapy during pregnancy. Preconception platelet counts in women whose pregnancies resulted in live birth were similar to those of women whose pregnancies ended in abortion. Other complications during pregnancy were rare. CONCLUSIONS: Patients with essential thrombocythemia have an increased risk of first-trimester abortion, which does not appear to be predictable or influenced by therapy. However, most patients are able to carry pregnancies to term with little or no risk of obstetric or thrombohemorrhagic complications during or after delivery. Overall, specific therapy during pregnancy did not appear to modify the clinical outcome, and the benefit of platelet apheresis during delivery could not be substantiated.
