Composition of a Suppressor Factor That Inhibits the Immune Response to Lactate Dehydrogenase B

Hybridomas obtained by fusion of lactute dehydrogenase B (LDH_B)-aciivatcd suppressor T (Ts) cells with the BW5147 thymoma produce a suppressor factor (TsF) that inhibits the proliferation of LDH_B-activated helper T (Th) cells. A similar factor (TsE) is contained in the extract of suppressor hybridomas. Both TsF and TsE are specifically retained by LDH_B-immunoadsorbent columns. Both consist of two components, an antigen-binding component (ABC) and possibly a major histocompatibility complex (MHC) component. The latter reacts with certain monoclonal antibodies specific for MHC determinants. The two components arc covalently associated in the IsF and noncovalcntly associated in TsE. Mixing of the two components reconstitutes the activity of the TsF or TsE. Disruption of the ABC's tertiary structure results in its inability to reconstitute suppressive activity on mixing with the MHC components. The ABC may contain an intrachain disulphide hond(s). Suppression is obtained when Th cells are incubated first with the ABC and then with the MHC component or vice versa, provided that the incubation period is at least 4 h. The MHC component is also produced by nonsuppressor hybridomas but not by mitogen-stimulated blasts or by the parental thymoma. The TsF is a glyeoprotein with a molecular weight ot about 120.000 to 160.000. The molecular weight of the ABC is about 76,000–86,000 and of the MHC component about 30,000–37,000.     

Induction of Human T Colony Formation by Phorbol Myristate Acetate

Phorbol myristate acetate (PMA) is a potent inducer of T colony formation by peripheral blood lymphocytes. A mean cloning efficiency of 0.3% (0.05-0.5%) is obtained with PMA concentrations of 100-1000 ng/ml. PMA-induced T colony formation does not require the presence of monocytes and therefore differs from other mitogens in this respect. Purified T-colony-promoting activity (TCPA) (devoid of phytohaemagglutinin (PHA)) increases PMA-induced T colony numbers and induces T colony formation at low PMA doses (0.01 to 1 ng), concentrations at which no T colonies are detected in the absence of added TCPA. PMA-induced colonies are mainly composed of cells bearing Fc receptors for IgM (54%), which is not the case for colonies obtained with PHA (11%). PMA-induced colony cells do not bind OKT3 and OKT4 monoclonal antibodies, whereas 23% are able to bind OKT8 antibody. These results demonstrate that PMA is a potent inducer of T colony formation and may therefore serve as a useful tool for the study of T-cell differentiation.     

Transcatheter Closure of Patent Foramen Ovale (PFO) in Patients with Paradoxical Embolism: Procedural and Follow‐Up Results after Implantation of the Amplatzer®‐Occluder Device

Background: Prevalence of patent foramen ovale (PFO) with detectable right‐to‐left shunt is higher in young adults with transient ischemic attack (TIA) and stroke compared to the general population. So far, published series included different occluder systems, various indications and regimens of postprocedural anticoagulation. In our experience, occluder systems may be associated with an increased prevalence of thrombus formation, which has also reported by other groups. The aim of the present study was to evaluate the follow‐up results after implantation of the Amplatzer® occluder in patients with PFO using a consistent anticoagulation regimen. Methods and Results: One‐hundred and fourteen patients with PFO (60 men; age: 47 ± 13 years) and ≥1 thromboembolic event were included. Other causes for embolism were excluded. PFO‐closure was successful in all patients. All patients were treated with aspirin (100 mg/day) and clopidogrel (75 mg/day) for 6 months. TEE was repeated at a mean of 10.3 months. Mean clinical follow‐up period was 18 ± 9 months. After a mean of 10 months, no patient had either a significant residual shunt nor a suspected thrombus formation on the occluder. During follow‐up, 5 patients suffered from neurological events (1 stroke, 2 TIAs, 2 epileptic seizures), though complete closure of the PFO was documented by TEE. One patient suffered from bleeding complications (upper GI‐bleeding). Conclusion: Percutaneous closure of PFO in symptomatic patients by Amplatzer® occluder represents an effective therapy with a low incidence of peri‐interventional complications and recurrent thromboembolism. Thrombus formations on the occluder system were not detected in this cohort. (J Interven Cardiol 2011;24:85–91)