The predominantly human sequence, high-affinity anticocaine monoclonal antibody (mAb) 2E2 was cleared slowly from mouse blood by a first-order process with an elimination t 1/2 of 8.1 days. Infused 2E2 also produced a dramatic dose-dependent increase in plasma cocaine concentrations and a concomitant decrease in the brain cocaine concentrations produced by an i.v. injection of cocaine HCl (0.56 mg/kg). At the highest dose of 2E2 tested (3:1, mAb/drug), cocaine was not detectable in the brain. Pharmacokinetic studies showed that the normal disappearance of cocaine from plasma was described by a two-compartment pharmacokinetic model with distribution t 1/2␣ and terminal elimination t 1/2␤ values of 1.9 and 26.1 min, respectively. In the presence of an equimolar dose of mAb 2E2, there was a 26-fold increase in the area under the plasma cocaine concentration-time curve (AUC) relative to the AUC in the absence of 2E2. Consequently, 2E2 decreased the volume of distribution of cocaine from 6.0 to 0.20 l/kg, which approximated that of 2E2 (0.28 l/kg). However, cocaine was still rapidly cleared from plasma, and its elimination was now described by a single-compartment model with an elimination t 1/2 of 17 min. Importantly, 2E2 also produced a 4.5-fold (78%) decrease in the cocaine AUC in the brain. Therefore, the effect of 2E2 on plasma and brain cocaine concentrations was predominantly caused by a change in the distribution of cocaine with negligible effects on its rate of clearance. These data support the concept of immunotherapy for drug abuse.Despite decades of basic and clinical research there is still no approved pharmacotherapy for the prevention of relapse in cocaine abusers (Vocci and Ling, 2005). The drug-induced reinstatement (priming) of drug self-administration behavior represents an animal model of relapse (DeWitt and Stewart, 1981) with the concentration of cocaine in the body a critical determinant of the probability of reinstating cocaine selfadministration (Norman et al., 1999(Norman et al., , 2002. Because the site of action of cocaine is presumably in the brain, decreasing the concentrations reaching the brain would be expected to decrease the probability of relapse. Antibodies with high affinity and specificity for cocaine would be expected to act as pharmacokinetic antagonists by sequestering cocaine in the peripheral circulation and preventing its entry to the brain. Indeed, active immunization of animals with hapten-carrier conjugates can elicit the production of polyclonal anticocaine antibodies with sufficient levels and affinity for cocaine that they can reduce the amount of cocaine entering the brain (Fox et al., 1996). Active immunization has also been shown to attenuate the behavioral effects (Carrera et al., 1995;Fox et al., 1996;Ettinger et al., 1997) and the priming effect (Carrera et al., 2000) of systemically administered cocaine in rats. Furthermore, the ability of active immunization to produce levels of polyclonal anticocaine antibodies in humans (Kosten et al., 2002) that we...

Apoptosis of leukocytes is known to strongly influence the immunopathogenesis of infection. Herein, we dissected the death pathways of murine Mφ infected with the intracellular pathogen, Histoplasma capsulatum. Yeast cells caused apoptosis of Mφ at a wide range of multiplicity of infection, but smaller inocula resulted in delayed detection of apoptosis. Upon infection, caspases 3 and 1 were activated, and both contributed to cell death but only the former was involved in apoptosis. The principal driving force for apoptosis involved the extrinsic pathway via engagement of TNFR1 by TNF-α. Infected Mφ produced IL-10 that dampened apoptosis. The chronology of TNF-α and IL-10 release differed in vitro. The former was detected by 2 h post-infection and the latter not until 8 h post-infection. In vivo, the lungs of TNFR1−/− mice infected for one day contained fewer apoptotic Mφ than WT whereas lungs of IL-10−/− mice exhibited more. Blockade of apoptosis by a pan-caspase inhibitor or by simvastatin sharply reduced release of TNF-α but enhanced IL-10. However, these treatments did not modify the fungal burden in vitro over 72 h. Thus, suppressing cell death modulated cytokine release but did not alter the fungal burden. These findings provide a framework for the early pathogenesis of histoplasmosis in which yeast cell invasion of lung Mφ engenders apoptosis triggered in part an autocrine TNF-α-dependent manner followed by release of IL-10 that likely prevents apoptosis of newly infected neighboring phagocytes.

The predominantly human sequence anti-cocaine monoclonal antibody (mAb), 2E2, has high affinity and specificity for cocaine and antagonizes cocaine distribution to the brain in mice. To determine whether 2E2 can alter the self-administration of cocaine in rats, both cocaine-induced reinstatement (priming) of self-administration, and the rates of cocaine consumption were assessed during daily sessions. After self-administration training, the rats' cocaine priming threshold values were stable over a 2-week baseline period. Furthermore, the rates of cocaine consumption at unit doses of 0.3 and 3.0 mol/kg were steady within sessions and stable between sessions. Then, 2E2 (120 mg/kg i.v.) or an equivalent dose of nonspecific human polyclonal IgG (control) was infused and daily sessions continued. 2E2 produced an initial, approximately 3-fold, increase in the cocaine priming threshold that declined toward baseline values over the subsequent 3 weeks, with an effect t 1/2 of approximately 4 days. In contrast to the substantial increase in the cocaine priming threshold, 2E2 produced only modest dose-dependent increases (42 and 18%) in the cocaine consumption rates, and these also gradually declined toward baseline values. There was no significant effect of the control IgG on the priming threshold or rates of consumption of cocaine. After infusion, antibody blood concentrations declined over time, and a two-compartment pharmacokinetic model generated values for the distribution and elimination half-lives of 0.5 and 11.6 days for 2E2 and 0.4 and 6.0 days for control IgG. 2E2 had a long-lasting effect on cocaine-induced priming, which may predict its efficacy as an immunotherapy for cocaine abuse.The drug-induced reinstatement (priming) of drug selfadministration behavior represents an animal model of some aspects of the relapse process (de Wit and Stewart, 1981;Shalev et al., 2002) in addicts. The cumulative concentration of cocaine is a critical determinant of the probability of reinstating cocaine self-administration in rats (Norman et al., , 2002. Because the site of action for cocaine is presumably in the brain, decreasing the drug concentrations reaching the brain would be expected to decrease the probability of relapse. Antibodies with high affinity and specificity for cocaine are hypothesized to sequester cocaine in the peripheral circulation and reduce its entry to the brain (Kosten and Owens, 2005). Pharmacokinetic antagonism is defined as a decrease in the concentration of an agonist at its site of action. Typically, the mechanism by which this is achieved is by increasing the rate of agonist clearance (Rang et al., 2007). Although this may occur with antibody Fab fragments targeting slowly cleared drugs such as digoxin (Bateman, 2004), this would not occur with monoclonal antibodies (mAb) targeting rapidly cleared drugs such as cocaine or nicotine (Keyler et al., 2005). Antibodies generally act as chemical antagonists by binding to and thereby reversibly inactivating drugs. As a consequence, anti-drug an...

The current study sought to determine whether prenatal 3,4-methylenedioxy-N-methamphetamine (MDMA) exposure from E14-20 in the rat resulted in behavioral sequelae in adult offspring. Prenatal MDMA exposure results in increased dopaminergic fiber density in the prefrontal cortex, striatum and nucleus accumbens of young rats. Since these areas are critical in response to novelty, reward, attention and locomotor activity, we hypothesized that prenatal MDMA exposure would produce significant changes in the performance of tasks that examine such behaviors in adult rats. Adult rats prenatally exposed to MDMA exhibited greater activity and spent more time in the center during a novel open field test as compared to controls. This increased activity was not reflected in normal home cage activity. Prenatal exposure to MDMA did not affect feeding or food reward. It did not alter cocaine self-administration behaviors, nor did it have an effect on the locomotor response to amphetamine challenge. Finally, while prenatal MDMA did not affect performance in the radial arm maze or the Morris water maze (MWM), these animals demonstrated altered performance in a cued MWM paradigm. Prenatal MDMA exposure resulted in perseverative attendance to a hanging cue when the platform in the MWM was removed as compared to controls. Together, these data demonstrate that prenatal exposure to MDMA results in a behavioral phenotype in adult rats characterized by reduced anxiety, a heightened response to novelty, and “hyperattentiveness” to environmental cues during spatial learning.