Adjuvants LT-K63 and CpG enhance the activation of dendritic cells in neonatal mice.

Dendritic cells (DC) play a major role in the priming of T cells and initiating specific immune responses. We assessed the effects of the adjuvants LT-K63 and CpG on neonatal DC in vivo and in vitro. Cytokine levels (IL-10, IL-12p70 and IL-12p40/IL-23p40) were measured and the expression of the activation markers CD86, CD40 and MHCII on CD11c+ DC was analysed by using FACS. The proportion of MHCII high CD11c+ DC was higher in neonatal mice immunized with a pneumococcal conjugate (PncTT) and LT-K63 or CpG compared with that when PncTT was alone. In vitro stimulation with LT-K63 enhanced the expression of CD86 more on CD11c+ DC from spleens of mice immunized as neonates than those immunized as adults, whereas in vitro stimulation with CpG enhanced the expression of CD86 and CD40 on CD11c+ DC similarly in both age groups. CpG stimulation in vitro enhanced IL-10 and IL-12(p70) production in mice immunized as neonates with PncTT and either adjuvant, but not PncTT alone. The adjuvants LT-K63 and CpG enhance the activation of CD11c+ DC in mice immunized as neonates and can thereby overcome one of the limiting factors in the initiation of the immune response to conjugate vaccines in early life. The fact that neonatal DC are more susceptible to stimulation with either adjuvant, LT-K63 or CpG, could imply that neonatal CD11c+ DC are more easily activated than adult CD11c+ DC, and /or be a consequence of the predominance of different DC subsets in neonatal and adult mice.

Effects of LT-K63 and CpG2006 on phenotype and function of murine neonatal lymphoid cells.

The immature state of the immune system of neonates makes them vulnerable to infectious agents, including Streptococcus pneumoniae. The aim of our study was to analyse and compare the effects of Escherichia coli heat-labile enterototoxin (LT)-K63 and CpG2006 on cells and key molecules of the neonatal immune system, using a previously established immunization model with pneumococcal polysaccharide of serotype 1 conjugated to tetanus toxoid (TT) (Pnc1-TT). The cellular response was evaluated by measuring cytokine secretion and proliferation upon in vitro stimulation with TT, the protein moiety of Pnc1-TT, and antibody (Ab) to both the polysaccharide (PS) and protein parts of the vaccine were measured by enzyme-linked immunosorbent assay (ELISA). Antigen (Ag)-presenting and co-stimulatory capacity of neonatal B-cells was evaluated by staining for major histocompatibility complex (MHC)II, CD80, CD86 and CD40. The results showed that both LT-K63 and CpG2006 significantly enhanced the neonatal Ab response to Pnc1-TT. Spleen cells from mice receiving LT-K63 showed enhanced proliferation and interferon (IFN)-gamma, interleukin (IL)-4, IL-5 and IL-10 secretion upon TT stimulation, whereas cells from mice receiving CpG2006 could only enhance IL-10 secretion. LT-K63 and to a lesser extent CpG2006 enhanced the capacity of B-cells to up-regulate the expression of co-stimulatory and activation markers compared with those of mice receiving Pnc1-TT alone. Thus, we conclude that LT-K63 markedly improves T-cell activation whereas the direct adjuvant effect of CpG2006 on neonatal B-cells may partly compensate for lower T-cell help resulting in enhanced neonatal Ab responses to both the TT and PS parts of the vaccine by both adjuvants.

Helivax Antex Biologics.

Antex Biologics is developing an oral vaccine against Helicobacter pylori infection as a potential treatment and prophylaxis for gastric ulcers. The vaccine incorporates a mucosal adjuvant and is in phase II trials [376332]. Enrollment for the trial was completed in September 2000 and results are expected in 2001 [382128]. In July 2000, Antex started a two-part phase Ib/II clinical trial of the vaccine. The first part was an open-label study to assess the general safety of the vaccine in uninfected and asymptomatic Helicobacter pylori-infected individuals. The second part was an expanded placebo-controlled study to evaluate safety and immunogenicity of the vaccine. The vaccine was generally well-tolerated and it generated an immune response in both infected and non-infected individuals [312681].

Immobilization of white-tailed deer with xylazine hydrochloride and ketamine hydrochloride and antagonism by tolazoline hydrochloride.

Fourteen penned and 17 free-ranging white-tailed deer (Odocoileus virginianus Rafinesque) were singularly or repeatedly immobilized with 100 mg xylazine hydrochloride (HCl) and 300 mg ketamine HCl. The mean times from intravenous injection to ambulation for 1.0, 2.0, and 4.0 mg/kg body weight doses of tolazoline HCl were 13.5, 10.5, and 9.2 min. Deer not receiving tolazoline HCl recovered in an average of 168 min. Heart rates significantly (P less than 0.001) increased from 47 to 83 beats/min after tolazoline HCl administration, representing a return to normal rate. Tolazoline HCl had no effect on respiratory rate. A total of 85 reversals with tolazoline HCl resulted in no apparent adverse reactions.

Yohimbine hydrochloride as an antagonist to xylazine hydrochloride-ketamine hydrochloride immobilization of white-tailed deer.

Thirteen captive and one free-ranging white-tailed deer (Odocoileus virginianus) were immobilized one to six times each with ketamine hydrochloride and xylazine hydrochloride during winter and spring in northern Minnesota. Administration of 0.09 to 0.53 mg of yohimbine hydrochloride per kg IV after each trial reversed the immobilization. The deer raised their heads within a median time of 2.0 min, stood in 6.0 min and walked away in 9.5 min. No adverse side effects were observed for several weeks following the immobilization.