Explore the vast range of titles available.

► Repeat-dose toxicity (mice) – no vaccine related adverse findings. ► Neurobehavioral toxicity (mice) – no vaccine related adverse findings. ► Local reactogenicity (rabbits) – no vaccine related adverse findings. ► All study designs reviewed by FDA prior to implementation. ► Enabled execution of Phase 1 clinical study. A recombinant botulinum vaccine (rBV A/B) is being developed to protect adults 18–55 years of age from fatal botulism caused by inhalational intoxication with botulinum neurotoxin complex (BoNT) serotype A, subtype A1 (BoNT/A1) and BoNT serotype B, subtype B1 (BoNT/B1). Fundamental to the advanced development process is an initial demonstration of product safety in animals. A comprehensive series of studies was conducted to evaluate the general toxicity, neurobehavioral toxicity and local reactogenicity of the rBV A/B vaccine prior to first use in humans. Toxicity was evaluated in CD-1 mice vaccinated with control material and three dosages of rBV A/B with or without Alhydrogel® by intramuscular (IM) injection on Study Days 0, 28, 56 and 70 in a volume of 100μL. Total immunizing protein given in each dose was either 0, 2, 4 or 8μg/animal. Local reactogenicity was evaluated in mice at the dosages given and in New Zealand white (NZW) rabbits using the same injection volume (0.5mL) and formulations (10, 20 and 40g/mL total antigen with 0.2% (w/v) Alhydrogel®) intended for human use. The rBV A/B vaccine produced no apparent systemic or neurobehavioral toxicity and only transient mild inflammation at the injection site. Together these results indicated a favorable safety profile for rBV A/B and supported its use in a Phase 1 clinical trial.

Background: To understand how the high-affinity IgE receptor (FcΕRI) communicates with downstream effectors, we focused on exploring the functional importance of the FcΕRI-mediated formation and localization of a signaling complex that contains the hematopoietic cell-specific scaffolding protein linker for activation of T cells (LAT) and the guanine nucleotide exchange factor Vav1. Methods: Using the mast cell line RBL-2H3, we explored the localization of these proteins by confocal microscopy and cell fractionation. Additionally, the mechanism of function and the importance of LAT and Vav1 to mast cells was studied in genetically disrupted mice and in mast cells derived from their bone marrow. Results: We found that LAT, Vav1 and the adapter molecule SLP-76 associated in detergent-resistant microdomains (lipid rafts) found in the plasma membrane upon FcΕRI stimulation. In the absence of LAT, mast cells showed a remarkable loss of the secretory response and reduced cytokine responses. Vav1 deficiency also affected secretion, although not to the extent of LAT deficiency, and inhibited IL-2 and IFN-γ production. LAT- and Vav1-deficient mice showed reduced blood histamine levels after a systemic anaphylaxis challenge as compared to their normal counterparts. Conclusions: The results demonstrate that LAT is a central mediator in IgE receptor signaling by regulating multiple signaling pathways that affect mast cell degranulation and cytokine production. Vav1, a component of this LAT-containing signaling complex, regulates a specific subset of these responses.

There remains a need for a rapid, reproducible method to identify chemicals with the capacity to elicit irritation, IgE-mediated, or T cell-mediated hypersensitivity responses in man. To fulfill this need, an irritancy/phenotypic analysis method was developed in female B6C3F1 mice. Following four consecutive days of dermal exposure (ear pinna), this method relies upon examination of three parameters: percent ear swelling and percent of B220+ and IgE+B220+ cells in the lymph nodes draining the dermal exposure site. Chemicals known to induce human irritation, IgE-mediated, or T cell-mediated hypersensitivity responses were utilized for the establishment of this procedure following their characterization in existing murine hypersensitivity assays. The draining lymph node IgE+ population was characterized as a possible end point for the identification of IgE inducing allergens. Time course experiments determined this population was optimal in animals ten days following initial dermal IgE-mediated or T cell-mediated allergen exposure, and its development positively correlated with total serum IgE levels in the IgE-mediated allergen exposed animals. The development of the IgE+ draining lymph node population was dose responsive, and was maximal in the draining lymph nodes when compared to distal lymphoid sites. Sensitizers (IgE and T cell-mediated) but not irritant exposure increased the draining lymph node B220+ population. Irritant exposure produced a significant increase in ear swelling. Based upon these results, a paradigm was developed for future studies: Irritant exposure will result in a significant ear swelling without altering the B220+ or IgE+B220+ populations. Exposure to sensitizers (IgE-mediated or T cell-mediated) will increase the B220+ population. The percent ear swelling will remain unchanged or significantly increase depending on the irritancy capacity of the sensitizer. Both the IgE+B220+ and B220+ populations will become elevated at the same test concentration following exposure to IgE-mediated hypersensitivity inducing allergens. At its peak, the percent of IgE+B220+ cells will equal-the percent of B220+ cells. Following exposure to T cell- mediated hypersensitivity inducing allergens, the B220+ population will become increased at a lower test concentration than the IgE+B220+ population. At its peak, the percent of IgE+B220+ cells will be less than half that of the percent of B220+ cells.