Interleukin (IL)-1beta, IL-6 and IL-8 in nasal secretions: a common role for innate immunity in viral bronchial infection in infants?
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Bronchial Diseases↗
Biomedical subjects
M Pino
Publications and source records attributed to M Pino.
Atomic force microscopy measurements of topography and friction on dotriacontane films adsorbed on a SiO2 surface.
We report comprehensive atomic force microscopy (AFM) measurements at room temperature of the nanoscale topography and lateral friction on the surface of thin solid films of an intermediate-length normal alkane, dotriacontane (n-C32H66), adsorbed onto a SiO2 surface. Our topographic and frictional images, recorded simultaneously in the contact mode, reveal a multilayer structure in which one to two layers of molecules adsorb adjacent to the SiO2 surface oriented with their long axis parallel to the interface followed by partial layers of molecules oriented perpendicular to the surface. The thicknesses of the parallel and perpendicular layers that we measured with the AFM agree with those inferred from previous x-ray specular reflectivity measurements on similarly prepared samples. We also observe bulk dotriacontane particles and, in contrast with our previous measurements, are able to determine their location. Above a minimum size, the bulk particles are separated from islands of perpendicularly oriented molecules by regions of exposed parallel layers that most likely extend underneath the particles. We find that the lateral friction is sensitive to the molecular orientation in the underlying crystalline film and can be used effectively with topographic measurements to resolve uncertainties in the film structure. We measure the same lateral friction on top of the bulk particles as on the perpendicular layers, a value that is about 2.5 times smaller than on a parallel layer. Scans on top of parallel layers indicate a constant height but reveal domains having different sublevels of friction. We explain this by the domains having different azimuthal orientations of the molecules.
Journal Article↗
In vitro evaluation of platelet reactivity toward annuloplasty devices treated with heparin coating: studies under flow conditions.
We have applied an in vitro perfusion model to explore the potential thrombogenicity of polyester annulolasty fabric used in valve repair and to investigate the possible thromboresistance characteristics conferred by a special heparin coating (Duraflotrade mark treatment). Samples of human blood from i) untreated or ii) heparin-coated extracorporeal circuits were recirculated through annular perfusion chambers containing a) untreated or b) treated annuloplasty cloth material. Perfusion experiments were performed at a shear rate of 600 s(-1) for 20 min. Platelet interaction with the material was morphometrically evaluated. In experiments performed with blood from untreated circuits and cloth material, the average cross-sectional area of platelet mass was 615 +/- 135 microm2. Treatment of cloth material with Duraflotrade mark statistically decreased the area of interacting platelets to 319 +/- 101 microm2 (*p < 0.05, n = 10). Blood samples from heparin-coated extracorporeal circuits showed a decrease of total area of platelets (308 +/- 58 microm2 vs 138 +/- 30 microm2, *p < 0.05, n = 9). The combined treatment of Duraflotrade mark in extracorporeal circuits and cloth material caused a more consistent reduction (p < 0.05). The in vitro perfusion experimental model was sensitive to evaluate the thrombogenic potential of Duraflotrade mark treatment. Our results indicate that the heparin coating of cloth material and extracorporeal circuits improves the biocompatibility of the original material and reduces the thrombogenic profile.
Aged↗
Antithrombotic effect of a new nitric oxide donor (LA419) on experimental thrombogenesis.
BACKGROUND: The ability of nitrous compounds to donate nitric oxide (NO), an agent with vasodilating and inhibitory effects on platelet function, has been considered a useful pharmacologic strategy for cardiovascular complications. The purpose of this study was to investigate the effects of a new NO donor, LA419, on platelet interaction in an ex vivo model with human blood circulating through collagen-rich surfaces. MATERIALS AND METHODS: Platelet adhesive and cohesive function were analyzed by morphometric procedures after perfusion techniques. Treated blood was exposed to thrombogenic surfaces and platelet interactions were morphometrically evaluated. RESULTS: All the concentrations studied of LA419 (10 microM, 20 microM and 100 microM) reduced overall platelet interaction with a collagen surface (27.19 +/- 4.72; 25.52 +/- 3.52; and 23.44 +/- 3.01, P < 0.05, respectively, vs. 32.31 +/- 1.61% in the control). The antithrombotic effect was confirmed by results in cross-sectional studies performed in arterial vessels exposed to circulating blood. Values of thrombus and covered surface at 20 microM LA419 were, respectively, 13.67 +/- 4.97% and 19.01 +/- 5.89%; respect to controls 34.80 +/- 5.29% and 37.93 +/- 5.34% (P < 0.05). Moreover, LA419 reduced significantly thrombus area (88.45 +/- 21.97 microm(2); P < 0.05) with respect to controls (168.45 +/- 21.97 microm(2)) and thrombus height, from an average of 10.27 +/- 1.05 microm in nontreated blood to 7.16 +/- 0.6 microm in treated samples (P < 0.05). CONCLUSION: From the present data we can conclude that LA419 possesses a strong antiplatelet action, as demonstrated by its ability to significantly inhibit the interaction of platelet with highly thrombogenic collagen surfaces.
Animals↗
Critical period for a teratogenic VLA-4 antagonist: Developmental effects and comparison of embryo drug concentrations of teratogenic and non-teratogenic VLA-4 antagonists.
BACKGROUND: Integrins such as VLA-4 (Very late antigen 4, integrin alpha4beta1) play key roles in cell-cell interactions that are critical for development. Homozygous null knockouts of the VLA-4 alpha4-subunit or VCAM-1 (VLA-4 cell surface ligand) in mice result in failure of the allantois and chorion to fuse leading to interrupted placentation and cardiac development and embryo lethality. Embryo-fetal studies of three VLA-4 antagonists, IVL745, IVL984, and HMR1031 [Crofts et al., Birth Defects Res B 71:55-68 (this issue), 2004] with exposure on gestation days (GD) 6-17 (rat), 6-18 (rabbit) or 6-15 (mouse) showed that only IVL984 treatment resulted in embryo lethality and cardiac defects. Objectives of the current study were to determine the critical period for inducing IVL984-related embryo-fetal effects, and to test the hypothesis that these effects were due to higher embryo drug concentrations. METHODS: IVL984 was administered at 40 mg/kg/day to pregnant rats on GD 4 and 5, GD 6 and 7, GD 8 and 9, GD 10 and 11, or GD 12 and 13. Animals were euthanized on GD 21 and uteri and fetuses were examined. A treatment period of GD 10-12 was selected for subsequent toxicokinetic (TK) studies in which IVL984, HMR1031, or IVL745 was administered to pregnant rats and rabbits. On GD 12, maternal plasma, extra-embryonic tissue (placenta and amniotic fluid), and embryonic tissue were collected and analyzed for drug concentrations. RESULTS: In the IVL984 critical period study in pregnant rats, treatment on GD 10 and 11 resulted in increased post-implantation loss, skeletal variations, and spiral septal defects similar to those observed in standard embryo-fetal development studies with treatment throughout organogenesis. There were no embryo-fetal effects after treatment on GD 4 and 5, GD 6 and 7, or GD 8 and 9. There was a single aorta malformation after treatment on GD 12 and 13. In the TK studies, IVL745, HMR1031, and IVL984 were all detectable in embryonic tissue and there was no evidence for accumulation. Rat and rabbit embryo exposures (AUC or dose-adjusted AUC) on GD 12 could not explain the observed teratology (IVL984<HMR1031<IVL745). Further analyses incorporating pharmacological activity, clearance, and protein binding data provided a positive correlation between embryonic exposure and teratogenic potency. CONCLUSIONS: The critical period for IVL984 in the rat, GD 10 to 11, corresponds to the expression of alpha-4 integrin on the chorion and VCAM-1 on the allantois and myocardium as well as chorioallantoic fusion and formation of the spiral septum. Embryo drug levels adjusted for pharmacological activity, clearance, and protein binding provide a possible explanation for the differing teratogenic potency of IVL984, HMR1031, and IVL745.
Abnormalities, Drug-Induced↗
Different embryo-fetal toxicity effects for three VLA-4 antagonists.
BACKGROUND: VLA-4 (Very late antigen 4, integrin alpha4beta1) plays an important role in cell-cell interactions that are critical for development. Homozygous null knockouts of the alpha4 subunit of VLA-4 or VCAM-1 (cell surface ligand to VLA-4) in mice result in abnormal placental and cardiac development and embryo lethality. Objectives of the current study were to assess and compare the teratogenic potential of three VLA-4 antagonists. METHODS: IVL745, HMR1031, and IVL984 were each evaluated by the subcutaneous route in standard embryo-fetal developmental toxicity studies in rats and rabbits. IVL984 was also evaluated in mice. Fetuses were examined externally, viscerally, and skeletally. RESULTS: IVL745 did not cause significant maternal or fetal effects at doses up to 100 or 250 mg/kg/day in rats or rabbits, respectively. HMR1031 treatment resulted in marked maternal toxicity and slight fetal toxicity at the highest tested doses of 200 and 75 mg/kg/day in rats and rabbits, respectively. HMR1031 embryo-fetal effects consisted of slightly lower body weight and crown-rump length in rats and minor sternebral defects in rabbits. IVL984 treatment resulted in minimal maternal effects at doses up to 40, 15, and 100 mg/kg/day in rats, rabbits, and mice, respectively (excluding abortions in rabbits). However, marked developmental effects were observed at the lowest tested IVL984 doses, 1, 0.2, and 3 mg/kg/day in rats, rabbits, and mice, respectively. IVL984 embryo-fetal effects consisted of increased total post-implantation loss due to early resorptions and high incidences of cardiac malformations and skeletal malformations and/or variations. Notably, spiral septal defects were observed in up to 76% of rat fetuses and up to 58% of rabbit fetuses. CONCLUSIONS: Dramatic differences in teratogenic potential were observed: IVL745 was not teratogenic, HMR1031 caused slight embryo-fetal effects at maternally-toxic doses, and IVL984 was a potent teratogen at doses where direct maternal toxicity was limited to abortions in rabbits. Prominent effects of IVL984 included embryo lethality and cardiac malformations including spiral septal defects in three species.
Abnormalities, Drug-Induced↗
The PFA-100 detects sub-optimal antiplatelet responses in patients on aspirin.
Although it is suspected that some patients with acute coronary syndromes (ACS) could have a sub-optimal response to aspirin (SASAR), currently a fixed dose of ASA is long-term used in all individuals. This study was designed to determine SASAR and whether a SASAR is a predictor for recurrence of ischemic events in patients on low-dose ASA with a previous ACS. One hundred patients taking ASA 100 mg/day were assessed at 1 and 6 months after a first ACS. SASAR was initially defined as a failure of the ASA treatment to significantly prolong the closure time in the Platelet Function Analyzer (PFA-100). SASAR in these samples was reconfirmed by conventional aggregometry. TXB2 levels were determined in plasma. At one month 49 patients showed SASAR in the PFA-100; only 25 of them showed SASAR by conventional aggregometry. At six months, 39 of 81 patients showed SASAR by PFA-100, but conventional aggregometry detected SASAR in only 12 of the 39 patients. TXB2 levels were significantly higher in patients with SASAR. Five patients with SASAR, by both tests, died during follow-up (p = 0.013). The PFA-100 detected a high rate of SASAR in patients with ACS. This instrument could be used to screen for suboptimal response to the antiplatelet action of ASA. Whether persistence of SASAR could relate to a higher risk of recurrence and how adjusting the dose of ASA could reduce the rate of SASAR are issues that deserve further investigations.
Aspirin↗
Evaluation of effects of rofecoxib on platelet function in an in vitro model of thrombosis with circulating human blood.
BACKGROUND: Cyclooxygenase (COX)-2-selective non-steroidal anti-inflammatory drugs have been used for anti-inflammatory therapy. However, it has also been described that they may increase risk of cardiovascular events. OBJECTIVES: To study the effects of COX2 inhibitor rofecoxib on platelet function using in vitro tests. Results were compared with those obtained in a parallel experiment with acetyl salicylic acid (ASA). METHODS: Studies of platelet aggregation, using different agonists, were performed by a turbidimetric method. Adhesive and cohesive function of platelets were analyzed by perfusion techniques, treated blood was exposed to thrombogenic surfaces and platelet interaction was morphometrically evaluated. RESULTS: Twenty-five micro M of rofecoxib induced a prolonged lag time and a reduction in the percentage of aggregation when arachidonic acid, ADP or collagen were used as agonists. In perfusion studies with parallel chamber rofecoxib 50 microM and ASA 500 microM reduced overall platelet interaction with the collagen surface (17.4 +/- 3.7, P < 0.05; vs. 32.1 +/- 2.6%P < 0.05 and 17.9 +/- 2.4, vs. 31.9 +/- 3.24, P < 0.05, respectively). In studies performed on annular chambers, 25 micro M of rofecoxib reduced platelet interaction; values of the thrombus and covered surface were 17.4 +/- 4.5%; P < 0.05 and 21.1 +/- 4.1%; P < 0.05, respectively, vs. 30.4 +/- 7.5% and 33.5 +/- 6.5 in the control. ASA did also impair thrombus formation but differences did not reach the levels of statistical significance. Moreover, rofecoxib but not ASA reduced significantly thrombus height and thrombus area (7.4 +/- 0.5 microM; P < 0.005 and 96.0 +/- 21.2 microM(2); P < 0.05 vs. control 11.2 +/- 0.9 microM and 220.0 +/- 47.7 microM(2), respectively). CONCLUSION: We conclude that under our experimental conditions, rofecoxib diminished platelet aggregation induced by different agonists and inhibited platelet-mediated thrombogenesis in an in vitro model of thrombosis.
Adenosine Diphosphate↗
Concentrates containing factor IX could improve haemostasis under conditions of thrombocytopenia: studies in an in vitro model.
BACKGROUND AND OBJECTIVES: We explored the effect on haemostasis of different factor IX (FIX) concentrates under thrombocytopenic conditions using an in vitro perfusion technique. MATERIALS AND METHODS: A moderate experimental thrombocytopenia (25 000-30 000 platelets/microl) was induced by means of a filtration procedure in blood anticoagulated with low-molecular-weight heparin. The effects of three different FIX concentrates - a prothrombin complex concentrate (PCC), an intermediate-purity concentrate (FIX/X), and a high-purity concentrate (HPFIX) - on platelet deposition and fibrin formation on subendothelium were assessed at two different shear rates (600/second and 1200/second). Activation of the coagulation system was monitored through assessment of prothrombin activation fragment 1 + 2 (F1 + 2). RESULTS: Fibrin deposition increased after addition of FIX concentrates, but only showed a significant increase in experiments performed after incubation of PCC at the lower shear rate (600/second) (64.25 +/- 9.61% vs. control 31.22 +/- 8.02%; P < 0.05). Addition of FIX concentrates caused a small increase in the percentage of platelet deposition and area of those aggregates. These differences reached levels of statistical significance in the presence of FIX/X and HPFIX in experiments performed at a shear rate of 600/second. F1 + 2 baseline values in anticoagulated thrombocytopenic blood were 1.15 +/- 0.13 nm and reached levels of 2.49 +/- 0.24 and 3.60 +/- 0.33 nm at shear rates of 600 and 1200/second, respectively. Increments in F1 + 2 observed after addition of different FIX concentrates always remained in the previous ranges. CONCLUSIONS: Data from the present study provide experimental support favouring the concept that FIX concentrates containing other activated factors could improve haemostasis under conditions of moderate thrombocytopenia.
Animals↗
[Merkel cell carcinoma].
The authors present 2 cases of Merkel cell carcinoma in the head and neck district, evaluating the characteristics and evolution. Merkel cell carcinoma is a rare, highly aggressive neuroendocrine cutaneous neoplasm which is often located in the head and neck district. This carcinoma has the same characteristics as small cell tumors and tends to significant metastatization both through the lymph nodes and through the blood. It is also prone to frequent recurrence. Today diagnosis is facilitated by electron microscopy and immunohistochemistry to search for neurofilaments and cytocheratin 20. The treatment of choice is radical surgery ensuring a tumor-free edge of at least 3 cm, associated with supplementary local radiotherapy. Recurrence is quite frequent despite the treatment strategies applied.
Aged↗
Benign symmetric lipomatosis (Madelung's disease).
We report on a 50-year-old man who presented with benign, symmetric lipomatosis and chronic alcoholic liver disease. The characteristic clinical features and a brief review of the current literature are presented.
Journal Article↗
Infusible platelet membranes improve hemostasis in thrombocytopenic blood: experimental studies under flow conditions.
BACKGROUND: The potential hemostatic effect of infusible platelet membranes (IPM; Cyplex, Cypress Bioscience) prepared from outdated human platelets is investigated. STUDY DESIGN AND METHODS: Increasing concentrations of IPM were added to blood samples anticoagulated with low-molecular-weight heparin, in which platelets and WBC counts had been experimentally reduced by a filtration procedure. Thrombocytopenic blood with IPM was circulated in a perfusion chamber at various shear rates (300, 600, and 1200/sec(-1)), and platelet and fibrin deposition on the surface of a damaged vessel was measured. Prothrombin fragments 1 and 2 (F1+2) levels were also monitored. RESULTS: Under conditions of severe thrombocytopenia (<6000 platelets/microL) IPM did not increase platelet deposition. However, a dose-dependent increase in fibrin deposition was observed with concentrations of IPM ranging from 0.5 to 2 mg per kg in perfusions at 300 and 600 per sec(-1) (p<0.05 vs. thrombocytopenic blood). Experimental studies performed under conditions of moderate thrombocytopenia and higher shear rates (25, 000-30,000 platelets/microL; at 600 and 1200/sec(-1)) showed that IPM concentrations equivalent to 0.5 or 1 mg per kg improved fibrin deposition (33.5 +/- 9.5% and 37.7 +/- 12.8%, respectively, vs. 22.7 +/- 5.2% in controls) and also promoted a moderate increase in platelet deposition, with a concomitant significant increase in the size of platelet aggregates (p<0.05). Exposure of thrombocytopenic blood to a damaged vessel resulted in an increase of F1+2 levels from 0.8 +/- 0.15 to 1.7 +/- 0.22 nM at 300 per sec(-1) and 1.94 +/- 0.46 nM at 600 per sec(-1). Postperfusion levels of F1+2 after the addition of IPM were always similar to levels in untreated controls. CONCLUSION: IPM promotes local procoagulant activity at sites of vascular damage under conditions of severe and moderate thrombocytopenia. IPM also appears to facilitate platelet cohesive functions under conditions of moderate thrombocytopenia.
Blood Platelets↗
Evaluation of acquired platelet dysfunctions in uremic and cirrhotic patients using the platelet function analyzer (PFA-100 ): influence of hematocrit elevation.
BACKGROUND AND OBJECTIVE: Patients with end-stage renal disease or advanced cirrhosis develop bleeding disorders characterized by defective interaction of platelets with damaged subendothelium. The anemia associated with both clinical entities has a negative influence on hemostasis. We evaluated alterations of platelet function in patients suffering from end-stage renal disease (n=21) or hepatic cirrhosis (n=20) using standard aggregometric techniques and the recently developed platelet function analyzer (PFA-100 ). The impact of low hematocrit was also analyzed. DESIGN AND METHODS: The hemostatic capacity of platelets was tested in the PFA-100 using citrated blood and standard cartridges containing collagen-ADP (COL-ADP) or collagen-epinephrine (COL-Epi). The hemodynamic influence of hematocrit was also evaluated in blood aliquots in which hematocrit was experimentally increased by adding red blood cells from the same patient. RESULTS: Aggregation studies demonstrated abnormal responses to several agonists in both group of patients. Closure times obtained by the PFA-100 for control blood samples were 87+/-3 sec for COL-ADP and 113+/-5 sec with COL-EPi cartridges. Closure times in uremic and cirrhotic patients with average hematocrits of 0.26 and 0.27 respectively were significantly prolonged (139+/-12 and 125+/-14 sec, respectively with COL-ADP and 194+/-29 and 151+/-15 sec with COL-Epi cartridges). A 5% increase in the hematocrit caused a reduction in the closure time to 111+/-7 sec (COL-ADP) and 143+/-14 sec (COL-Epi) in the uremic group and to 86+/-4 sec (COL-ADP) and 115+/-16 sec (COL-Epi) in the cirrhotic group. Our studies confirm the platelet dysfunction in uremic and cirrhotic patients. INTERPRETATION AND CONCLUSIONS: The PFA-100 device proved to be useful for testing alterations of primary hemostasis in these acquired disorders and was sensitive enough to detect modifications in hemostasis caused by elevations in hematocrit. Conventional aggregometric tests were able to identify the intrinsic platelet abnormality in uremic and cirrhotic conditions, while the PFA-100 seemed more sensitive in detecting the negative influence of the hematocrit reduction.
Adult↗
[Functionality of von Willebrand factor present in Fanhdi: adhesion to the vascular subendothelium in vitro].
PURPOSE: To study the ability of VWF present in a plasma derived high purity factor VIII concentrate (> or = 100 UI FVIII/mg of protein, Fanhdi) to promote deposition and platelet adhesion on the injured vessel wall, as an indicator of the functionality of said VWF. MATERIAL AND METHODS: An in vitro perfusion system was employed. Adequate proportions of platelets and red cells were suspended in a human albumin solution. Aliquots of the studied product were added to obtain levels of 0.4 and 0.8 VWF:AG U/mL in the perfusates. As a comparative group, cryoprecipitate was assayed at similar VWF:Ag doses. Perfusions were performed on rabbit de-endothelialized abdominal aorta segments, placed in annular perfusion chambers, at 37 degrees C and at a flux of 140 mL/min (800 s-1) for 10 min. Results were evaluated as surface covered by platelets and as the percentage ratio between thrombus and surface covered by platelets. FVIII activity was determined by one stage clotting assay. VWF:RCo activity was determined by aggregometry and VWF:Ag by ELISA. RESULTS: The VWF:Ag/FVIII:C ratio of Fanhdi is 1.57, while VWF:Roc/FVIII:C ratio is 1.15. The values of platelet deposition obtained, expressed as times of increase in the surface covered by platelets, considering the basal value (without VWF added) as 1, were: Cryoprecipitate 0.4 = 1.93; Cryoprecipitate 0.8 = 2.21; Fanhdi 0.4 = 2.99; Fanhdi 0.8 = 3.40. The ratios between thrombus and surface covered are 13.23%, 23.84%, 42.23%, 21.93% and 26.25% respectively. CONCLUSIONS: These data show that VWF present in Fanhdi maintains a high degree of functionality, promoting platelet adhesion on subendothelium under flow conditions, after its incorporation into an albumin-platelet-red cell preparation and resulting in a significant increase in platelet adhesion when compared to the VWF-free basal control.
Animals↗
Proteinuria and albumin homeostasis in the nephrotic syndrome: effect of dietary protein intake.
Nephrotic syndrome is analyzed in the light of interventions designed to decrease proteinuria and renal injury. The effect of dietary protein intake on urinary protein losses and albumin homeostasis are discussed on the basis of the pathophysiologic mechanisms known to account for changes in renal function of nephrotic patients. In addition, the effect of angiotensin-converting enzyme inhibitors for reduction of proteinuria is discussed in terms of the modulation of glomerular permselectivity and hemodynamics.
Albumins↗
Protein structure-based design of potent orally bioavailable, nonpeptide inhibitors of human immunodeficiency virus protease.
A class of potent nonpeptidic inhibitors of human immunodeficiency virus protease has been designed by using the three-dimensional structure of the enzyme as a guide. By employing iterative protein cocrystal structure analysis, design, and synthesis the binding affinity of the lead compound was incrementally improved by over four orders of magnitude. An inversion in inhibitor binding mode was observed crystallographically, providing information critical for subsequent design and highlighting the utility of structural feedback in inhibitor optimization. These inhibitors are selective for the viral protease enzyme, possess good antiviral activity, and are orally available in three species.
Administration, Oral↗
[Fluconazole in treatment of urinary candidiasis. Experience with 24 patients].
Since fluconazole achieves high urine concentrations, we assessed its usefulness in the treatment of urinary candidiasis. We studied 24 patients (8 male) aged 23 to 97 years old, that presented pyuria with a negative urine culture for bacteria and fungal colony counts in urine of 10(4) CFU/ml or more. Isolated strains were Candida albicans in 20 cases, Candida kefyr in one case, Candida glabrata in one case and Candida spp in two cases. All patients were treated with fluconazole in doses of 50 to 100 mg/day for 2 to 4 weeks. The fungus was eradicated in 21 patients (88%), the infection persisted in two (8.5%) and one had a relapse (4.2%). Two patients had transient elevations of transaminases, one had abdominal pain and one, a purpuric syndrome without thrombocytopenia in whom the drug was discontinued. It is concluded that fluconazole is efficacious and safe in the treatment of urinary candidiasis.
Adult↗
Phenotypic and functional characterization of T cells from patients with myasthenia gravis.
A study of cell surface phenotypes of PBL of myasthenia gravis (MG) patients showed that their T cells had a significantly higher percentage of 4B4+ T cells (the helper/inducer subset) than age- and sex-matched controls. The PBL of MG patients proliferated significantly higher than those of normal subjects (NS) in response to the purified alpha chain of the acetylcholine receptor (AChR). Anti-AChR antibody was present in sera of 88% of MG and none of the NS. The PBL B cells from MG only, when cultured with autologous T cells and stimulated with either pokeweed mitogen (69%), or AChR-alpha chain (38%), secreted antibody to AChR-alpha chain, whereas T and B cells alone secreted no antibody. T cells from PBL of MG patients were more readily cloned than T cells of NS, by limiting dilution, in the presence of recombinant IL-2 and in the absence of AChR-alpha chain. About 50% of T cell clones from MG patients, compared to none from NS, proliferated to AChR-alpha chain. This response was HLA-DR restricted. MG T cell clones did not display significant cytotoxic activity, as compared to control T cell clones. Our results indicate that in MG, 4B4+ regulatory T cells play their role in the pathogenesis of MG, not by cytotoxicity, but more likely by their ability to stimulate specific antibody production by B cells.
Adult↗