The role of CTLA-4 in tolerance induction and ttigen administration cell differentiation in experimental autoimmune encephalomyelitis: i. v. antigen administration

Interactions between B7 molecules on antigen-presenting cells and CTLA-4 on T cells have been shown to be important in establishing tolerance. In the present study, we examined the kinetics of tolerance induction following i.v. administration of myelin basic protein (MBP) Ac1-11 in mice transgenic for a TCR V(beta)8.2 gene derived from an encephalitogenic T cell clone specific for MBP Ac1-11. Examination of the lymph node cell (LNC) response 10 days after antigen administration demonstrated an accentuation of i.v. tolerance induction with anti-CTLA-4 blockade. Anergy was induced in splenocytes by i.v. antigen administration as shown by a decrease in MBP-specific proliferation and IL-2 production, and anti-CTLA-4 potentiated this effect. In addition, i.v. antigen plus anti-CTLA-4 and complete Freund's adjuvant was not encephalitogenic. Interestingly, i.v. tolerance (a single injection) did not inhibit experimental autoimmune encephalomyelitis (EAE) and anti-CTLA-4 administration did not alter this phenotype. These results suggest that while the majority of MBP-specific T cells are tolerized by i.v. antigen and that this process is potentiated by anti-CTLA-4 administration, a population of T cells remains that is quite efficient in mediating EAE.

The role of CTLA-4 in tolerance induction and T cell differentiation in experimental autoimmune encephalomyelitis: i.p. antigen administration

Recent evidence suggests that co-stimulation provided by B7 molecules through CTLA-4 is important in establishing peripheral tolerance. In the present study, we examined the kinetics of tolerance induction and T cell differentiation following i.p. administration of myelin basic protein (MBP) Ac1-11 in mice transgenic for a TCR V(beta)8.2 gene derived from an encephalitogenic T cell clone specific for MBP Ac1-11. Examination of the lymph node cell response after antigen administration demonstrated a dependence on CTLA-4 for i.p. tolerance induction. Examination of splenocyte responses suggested that i.p. antigen administration induced a T(h)2 response, which was potentiated by anti-CTLA-4 administration. Interestingly, i.p. tolerance was able to inhibit the induction of experimental autoimmune encephalomyelitis and anti-CTLA-4 administration did not alter this phenotype, suggesting that CTLA-4 blockade did not block tolerance induction. Thus, T cell differentiation and the dependence on CTLA-4 for tolerance induction following i.p. antigen administration differs between lymph node and spleen in a model of organ-specific autoimmunity.

Regulation of experimental autoimmune encephalomyelitis with insulin-like growth factor (IGF-1) and IGF-1/IGF-binding protein-3 complex (IGF-1/IGFBP3)

Insulin-like growth factor (IGF)-1 is a cytokine that promotes oligodendrocyte development and myelin production. This study investigated whether treatment of chronic, relapsing murine experimental autoimmune encephalomyelitis (EAE) with IGF-1 or IGF-1 associated with its binding protein, IGFBP3, altered the course of disease. Administration of IGF-1/IGFBP3 (1-100 mg/kg per day) delayed the onset of disease in a dose-dependent manner and histologic examination showed a delay in inflammatory cells entering the central nervous system. However, once signs of EAE developed, disease was enhanced in the mice that had been given the highest dose of IGF-1/IGFBP3. Treatment with IGF-1/IGFBP3 after the onset of signs resulted in a severe relapse. Administration of free IGF-1 (10 mg/kg per day) provided mild protection when given before disease onset, but did not significantly alter the course of disease if given after disease onset. Possible mechanisms that could explain the altered disease in IGF-1/IGFBP3-treated mice included (a) IGF-1/IGFBP3 administration delayed the onset of EAE by downregulating ICAM-1 gene expression in the central nervous system, and (b) IGF-1/IGFBP3 treatment of EAE resulted in more severe disease due to enhanced expansion of encephalitogenic T cells. Although IGF-1 may enhance remyelination, these results indicate that administration of IGF-1 associated with IGFBP3 may also accentuate autoimmune demyelinating disease.

Aerosolized amiloride: dose effect on nasal bioelectric properties, pharmacokinetics, and effect on sputum expectoration in patients with cystic fibrosis

Aerosolized amiloride normalizes the excessive sodium absorption cystic fibrosis (CF) respiratory epithelium. The aims of this study were to assess the dose-effect relationship and the duration for which amiloride inhibits Na+ transport, to determine acute and chronic pharmacokinetics, and to test the effect of acute aerosolized amiloride on the amount of sputum expectorated. The effect of inhaled amiloride was assessed principally by nasal potential difference (PD) measurements. Amiloride serum levels were measured in 23 patients after inhalation of different doses of aerosolized amiloride. Twenty CF patients inhaled amiloride (10(-3)M) or a placebo in a double-blinded, randomized order, and sputum production was quantitated. The results of this study showed that maximal initial PD inhibition was achieved by 6 x 10(-3)M of amiloride. The duration of inhibition of PD (effective time until return to 50% delta PD [ET50] after nasal administration) was dose dependent (10(-3)M, 39 +/- 0.8 minutes; 10(-2)M; 133 +/- 14 minutes). Amiloride serum levels were below 2.5 ng/ml in 20 of 28 patients; levels were above 5 ng/ml only within 4 hours after high dose inhalation (10(-2)M). In the double-blinded, crossover study, more sputum was expectorated after amiloride inhalation as compared with that after a placebo (P < 0.05). In conclusion, the bioelectric effects of amiloride and serum levels after inhalation are dose dependent, and amiloride is effective at inducing sputum expectoration in CF.

Conventional and modified nasal potential-difference measurement in cystic fibrosis

Cystic fibrosis (CF) is associated with impaired ion transport across epithelial membranes and an increased transepithelial potential difference (PD) that can be measured in airway epithelium. The aim of this study was to investigate the diagnostic value of nasal PD in CF, and to test a modified approach to the measurement of this PD. The reproducibility and diagnostic sensitivity and specificity of nasal PD measurements were tested with the perfusion technique and with a simplified modification of the technique done with a novel, solid-state exploring electrode. With the perfusion method, basal PD values were different in CF patients (mean +/- SEM: -51.6 +/- 0.9 mV, n = 104) than in normal (-15.5 +/- 0.9 mV, n = 58, p < 0.01) subjects. CF patients with acute rhinitis or other nasal pathology had mean PD values that were intermediate between those of the patients and normal and disease-control groups (-28.3 +/- 1.2 mV, n = 40, p < 0.01, different from normal). The diagnostic sensitivity of the perfusion method for CF was 91.3%, and the specificity was 96.4%. PD measurements with the modified technique correlated highly with the results achieved with the perfusion method (r = 0.94, n +/- 158). The measurement of nasal PD effectively distinguishes CF from control subjects. Care must be taken in the interpretation of measurements made on acutely inflamed epithelium. The modified method was simpler than the conventional perfusion technique, and equally effective.

[Elimination of secretions in CF patients under amiloride inhalation]

Inhaled amiloride reduces active absorption of sodium of respiratory epithelium in CF patients and so, transiently, diminishes loss of water. 10 CF patients, 8 to 28 years of age, were examined on two days. First day, they inhaled in a randomised order isotonic saline and a solution of amiloride hydrochloride (0.3 mg/ml) one after another, each inhalation taking twenty minutes. Second day, inhalations were performed in an inverse order. To intensify the effect of inhalation, the inhalation procedure was combined with "autogenic drainage", a special kind of physiotherapy. Main criterion for evaluation was the amount of expectorated sputum. Mean increase of sputum during amiloride inhalation in comparison to saline was +50.4%. Patients and physiotherapist observed a liquefaction of secretion and a decrease of coughing by amiloride and a support of physiotherapy. These results suggest a beneficial clinical effect of regular amiloride inhalation in CF patients.

[Therapy of pituitary dwarfism with recombinant human growth hormone. A multicenter study]

During the period from 1982 to 1985, biosynthetic growth hormone (methionyl-hGH) was administered to 55 children with pituitary growth deficiency, 49 with idiopathic, six with other forms of the disorder. Preparations with a relatively high content of Escherichia coli polypeptides (ECP) were given to 32 children (group I), those with a markedly reduced ECP content to 12 (group II), while 11 children received almost ECP-free preparations (group III). The treatment achieved an intensive rise of growth acceleration in all three groups. At the same time, somatomedin C, biological somatomedin activity and alkaline phosphatase rose steeply, reaching a maximum after six months and remaining at high concentrations even thereafter. High antibody titres against ECP and hGH (with high binding capacity) were demonstrated in group I children, significantly lower titres with little binding capacity in those of group II, while most of those in group III had no measurable antibodies. Even in high concentrations the antibodies did not have any inhibiting effect on growth. No positive correlation between antibody titre and growth velocity was demonstrable. An exception was a boy with an allergy in group I, who had a maximal antibody titre and, at the same time, a high serum concentration of IgE. He had marked delay in growth which, however, quickly became normal on administration of extractive hGH.