Propranolol efficacy as a novel adjuvant for immunization against Toxoplasma gondii tachyzoites.

Severe or lethal damages, caused by Toxoplasma gondii infection in congenital cases and immunocompromised patients implies the necessity for development of a vaccine and an appropriate adjuvant would be needed to elicit a protective Th1 biased-immune response. The adjuvant activity of propranolol was surveyed and compared with alum by immunization of BALB/c mice with protein components of T. gondii tachyzoites. Five groups of BALB/c mice were immunized with phosphate buffered saline (negative control), Toxoplasma lysate antigen (TLA), alum plus TLA, Propranolol plus TLA, and alum, propranolol and TLA. Immunization efficacy was evaluated by lymphocyte proliferation and DTH tests, challenge with live tachyzoites, IFN-γ production by spleen cells, serum TNF-α concentration and anti- Toxoplasma total IgG, IgG1 and IgG2a measurements. Mice of the PRP-TLA group induced significantly more IFN-γ and TNF-α production and lymphocyte proliferation than other groups. This group of mice also showed more anti-T. gondii IgG2a and DTH responses and showed a significantly increased survival time after challenge. These findings indicate that propranolol as an adjuvant in combination with TLA, may enhance cellular immunity against T. gondii.

A novel adjuvant, mixture of alum and the beta-adrenergic receptor antagonist propranolol, elicits both humoral and cellular immune responses for heat-killed Salmonella typhimurium vaccine.

OBJECTIVE: To determine the efficacy of the mixture of propranolol (PRP), a beta-adrenergic receptor antagonist, and alum, as a new adjuvant, in the induction of humoral and cellular immunity in response to heat-killed Salmonella typhimurium (S. typhimurium) (HKST) as a model vaccine. METHODS: BALB/c mice were divided into five groups. Mice in the experimental groups received either the HKST vaccine alone or in combination with the adjuvant alum, PRP or the alum-PRP mixture. Mice in the negative control group received phosphate-buffered saline. All mice were immunized two times on days 0 and 14. Two weeks after the last immunization, immune responses to S. typhimurium were assessed. RESULTS: Administration of the alum-PRP mixture as an adjuvant increased the ability of the HKST vaccine to enhance lymphocyte proliferation, shifted the immune response towards a T-helper (Th) 1 pattern and increased S. typhimurium specific IgG, IgG2a and IgG1. This resulted in improved protective immunity against S. typhimurium. CONCLUSION: Administration of the alum-PRP mixture as an adjuvant in combination with the HKST vaccine, can enhance both humoral and cellular immunity and shift the immune responses to a Th1 pattern.

Combination of recombinant human growth hormone and propranolol decreases hypermetabolism and inflammation in severely burned children.

OBJECTIVE: Recombinant human growth hormone (rhGH) is a salutary modulator of posttraumatic metabolic responses. However, rhGH administration is associated with deleterious side effects, such as hyperglycemia, increased free fatty acids, and triglycerides, which limit its use. Administration of beta-blocker attenuates cardiac work and resting energy expenditure after severe thermal injury and improves fat metabolism and insulin sensitivity. Therefore, the combination of rhGH plus propranolol appears ideal. The aim of the present study was to determine whether rhGH plus propranolol improves hypermetabolism and the inflammatory and acute phase response after severe burn without causing adverse side effects. DESIGN: Prospective randomized control trial. SETTING: Shriners Hospitals for Children. PATIENTS: Fifteen pediatric patients with burns > 40% total body surface area, 0.1-16 yrs of age, admitted within 7 days after burn. Fifteen children were matched for burn size, age, gender, inhalation injury, and infection and served as controls. INTERVENTIONS: Patients in the experimental group received rhGH (0.2 mg/kg/day) and propranolol (to decrease heart rate by 15%) for > or = 15 days. MEASUREMENTS AND MAIN RESULTS: Outcome measurements included resting energy expenditure, body composition, acute phase proteins, and cytokines. Both cohorts were similar in age, burn size, gender, and accompanying injuries. Percent predicted resting energy expenditure significantly decreased in patients receiving rhGH/propranolol (Delta -5% +/- 8%) compared with controls (Delta +35% +/- 20%) (p < .05). rhGH/propranolol administration significantly decreased serum C-reactive protein, cortisone, aspartate aminotransferase, alanine aminotransferase, free fatty acids, interleukin-6, interleukin-8, and macrophage inflammatory protein-1beta when compared with controls, while growth hormone/propranolol increased serum insulin-like growth factor-I, insulin-like growth factor binding protein-3, growth hormone, prealbumin, and interleukin-7 when compared with placebo (p < .05). CONCLUSIONS: rhGH in combination with propranolol attenuates hypermetabolism and inflammation without the adverse side effects found with rhGH therapy alone.

Role of leukotrienes in post-allergic propranolol-induced bronchoconstriction in guinea-pigs.

BACKGROUND: Administration of propranolol can provoke bronchoconstriction only in asthmatic patients. Recently we developed an animal model for propranolol-induced bronchoconstriction (PIB). Our working hypothesis is that such bronchoconstriction may result from the inflammatory mediators released by an allergic reaction. OBJECTIVES: Our goal in this study was to determine which products of arachidonate 5-lipoxygenase pathway are involved in the PIB. METHODS: Propranolol at a concentration of 10 mg/mL was inhaled 20 min after antigen challenge in passively sensitized, anaesthetized and artificially ventilated guinea-pigs. Two different sulfidopeptide leukotriene (s-LT) antagonists, ICI198 615 in the doses of 0.03 and 0.3 mg/kg and vehicle and KCA757 in the doses of 1 and 5 mg/kg and vehicle, and a LTB4 antagonist ONO4057 in the doses of 1 and 10 mg/kg and vehicle were injected intravenously 15 min after antigen challenge. Effects of an anticholinergic agent atropine sulphate (5mg/kg) and an alpha-adrenergic blocker phentolamine (0.3 and 3 mg/kg) were examined in the same way. RESULTS: Bronchoconstriction occurred when 10 mg/mL of propranolol was inhaled 20 min after antigen challenge. Both ICI198 615 and KCA757 administered intravenously 15 min after antigen challenge reduced the PIB in a dose-dependent manner while ONO4057 did not alter the PIB. Atropine or phentolamine did not change the PIB. CONCLUSIONS: These results suggest that mediator mechanism, but not cholinergic or alpha-adrenergic nerve, is important in the PIB which developed after the allergic bronchoconstriction in our guinea-pig model and that s-LTs but not LTB4 have an important role in the pathophysiology of the PIB.

Towards artificial antibodies prepared by molecular imprinting.

The new technique of molecular imprinting has increasingly been adopted by research laboratories worldwide during the last few years. We have studied the use of such imprints against drugs as artificial antibody-binding mimics in competitive radioimmuno-style binding assays. The recognition sites "molded" in the polymers mimic the binding sites of natural antibodies in their interactions with the target antigen. Binding constants are as low as 4.0 nmol/L for a small number of well-defined sites, and cross-reactivities are similar to or better than those observed with biological antibodies. In some cases, the polymers have been used to determine drug concentrations in human serum specimens.

Immunoaffinity isolation of the sulfate conjugate of 4'-hydroxypropranolol from plasma.

Selective extraction of sulfate conjugates of basic drugs from biological matrices has been difficult because of their highly polar nature. Immunoaffinity isolation may be the best solution to this analytical problem. This was tested for a model compound, the metabolite 4'-hydroxypropranolol sulfate (HOPS), which was effectively extracted from plasma by a column containing antibodies to the parent drug propranolol. The specificity was very high, giving little interference from the biological material in subsequent high-performance liquid chromatographic analysis with fluorometric detection. The method for HOPS was highly reproducible and provided a sensitivity of 1 ng/ml plasma. The technique was applied to measurements of HOPS in plasma after therapeutic doses of propranolol as well as to the individual enantiomers after chiral derivatization.

Selective antibodies to propranolol enantiomers produced from a new conjugate.

A selective antibody to (S)-propranolol enantiomer was produced in rabbits by immunization with a new conjugate of N-aminopropylpropranolol-albumin. A hapten was first prepared by condensing (S)-propranolol or the racemate with 3-bromopropylphthalimide followed by hydrazinolysis, and the resulting compound conjugated to serum albumin by means of a glutaraldehyde- or carbodiimide-mediated reaction. Rabbits were immunized, and titres and specificity of antibodies were determined by ELISA. The antibodies obtained were tested with (S)-, (R)-, (R,S)-propranolol, and other structural analogs. Selective (S)-antibodies recognized (S)-propranolol 20 times more avidly than (R)-isomer while an antiserum against (R,S)-propranolol recognized both (S)- and (R)-isomers to about the same degree.

The effect of adrenoceptor agonists and antagonists on histamine-induced wheal response in the skin of normal subjects and atopic patients.

The role of the adrenergic mechanism in the pathogenesis of atopic diseases is controversial. Recent experimental and clinical reports have suggested that beta-2 adrenergic stimulation impairs and beta-2 adrenergic blockade enhances the histamine effect on vascular permeability. This led us to study the effect of salbutamol and of propranolol on histamine-induced cutaneous response in 13 healthy subjects and in 16 patients with allergic oculo-rhinitis. Both in normal subjects and in atopic patients salbutamol attenuated the whealing response to histamine and the protective effect of salbutamol was counteracted by propranolol. The ability, however, of salbutamol to inhibit histamine-induced response was significantly reduced in 50% of atopic patients. These findings suggest that beta-2 adrenergic hyporesponsiveness is present in some allergic patients.

Stereospecific antibodies to propranolol.

The beta-adrenergic antagonist propranolol was activated through its side chain, coupled to bovine serum albumin, and injected into BALB/c mice. After fusion of the splenocytes from these immunized mice with the NS-1 myeloma cell line, two hybridomas, producing monoclonal anti-propranolol antibodies, were isolated. Clone P-49 was monospecific for propranolol, with a significant preference for the 1-stereoisomer, as compared to the d form. On the other hand, clone P-28 cross-reacted with alprenolol as well as some other beta-antagonists. Both classes of antibodies competed with A431 epidermoid carcinoma beta 2-adrenoceptors for the binding of [3H]propranolol. When ascites cells from clone P-28 were fixed with glutaraldehyde, the anti-propranolol monoclonal antibody became cell bound. These cell-bound P-28 antibodies bind propranolol and other beta-adrenergic ligands with a similar ranking order to the soluble monoclonal antibody. The cell-bound antibody displayed a 5-fold higher affinity towards 1-propranolol than the soluble monoclonal antibody. The practical implications of these findings are discussed.

Monoclonal antibodies embedded in their hybridoma cells: an immunodiagnostic concept.

Aldehyde fixation of hybridoma cells during active production of monoclonal antibodies (MAbs) resulted in the formation of an insoluble phase because a large number of immunologically active antibody molecules were immobilized on the fixed hybridoma cells. Such MAb preparations specific to large protein molecules and small haptens were used for the development of a homogeneous immunoassay concept.

Comparison of acebutolol and propranolol in essential hypertension.

A multicenter, double-blind study compared oral acebutolol (n = 186) with propranolol (n = 190) in the treatment of mild to moderately severe essential hypertension (diastolic greater than or equal to 95 to 129 mm Hg). Both beta blockers produced significant and comparable reductions in diastolic, systolic, and mean arterial blood pressures of 16%, 12%, and 14% on acebutolol and 15%, 12%, and 14% on propranolol (all p less than 0.01). At equipotent, antihypertensive doses, acebutolol induced significantly less reduction in resting heart rate than propranolol (13% on acebutolol, 17% on propranolol, p = 0.02). The mean effective doses of acebutolol and propranolol were 738 mg and 231 mg, respectively. Significantly fewer acebutolol patients experienced central nervous system side effects (acebutolol, n = 50; propranolol, n = 75; p = 0.01) or withdrew from the study prematurely due to side effects (acebutolol, n = 11; propranolol, n = 29; p less than 0.01). No clinically significant trends in abnormalities of laboratory parameters were seen, and there were no statistically significant differences in the development of positive antinuclear antibody titers between the two treatment groups. It is concluded that acebutolol is as effective as propranolol in the treatment of hypertension, and acebutolol was better tolerated on the basis of heart rate and central nervous system side effects.

Effect of beta-adrenergic blockade, pertussis vaccine and Freund's adjuvant on reaginic antibody response in mice.

IgE synthesis has been reported to be inhibited by theophylline and dibutyryl cyclic adenosine monophosphate and increased by pertussis vaccine. This study was done to determine if chronic beta-adrenergic blockade affects IgE antibody production. 72 C57BL/10J mice were sensitized with egg albumin (EA, 125 microng). Groups included: (1) EA alone; (2) EA + complete Freund's adjuvant (FA); (3) EA + B. pertussis (8 X 10(9) organisms); (4) EA + propranolol (0.5 mg/kg) 3 times/day; (5) EA + FA + propranolol; (6) saline alone. Booster was given on day 49. Group 1, given EA alone, failed to develop any passive cutaneous anaphylaxis (PCA) antibodies even after booster, whereas the 72-hour PCA titers ranged from 1/64 to 1/256 for groups treated with propranolol and propranolol + FA, respectively. The results suggest that chronic beta-adrenergic blockade enhances IgE antibody formation.

Stereospecific radioimmunoassay for propranolol isomers.

Antisera against propranolol were produced in rabbits immunized with propranolol conjugated to bovine serum albumin. The antiserum against dl-propranolol recognized both d- and l-propranolol to the same degree. However, antiserum against l-propranolol was able to discriminate the l-propranolol selectively. The antisera were used to develop radioimmunoassays for dl-propranolol and l-propranolol. The assay can detect as little as 10 pg of propranolol. Metabolites of propranolol do not interfere with the assay unless concentrations are very high. Serum and heart levels of l-propranolol and the d-isomer were determined in the rat after i.v. injection (1 mg/kg) of dl-propranolol. l-Propranolol declines rapidly in the blood after the injection. Concomitantly, there is a rapid accumulation of l-propranolol by the heart. The d-form of propranolol remains in the blood and is metabolized rapidly as reflected by a shorter half-life (23.8 minutes) than the one found for l-propranolol (5.20 minutes).