Fluorescent detection of major Abs was performed using Alexa Fluor 555 goat anti rabbit IgG (Life technologies, Grand Island, NY) at a 1:500 dilution for anti-PPD Ab, and Alexa flour 488 or 555 Donkey anti-mouse IgG (Life technologies) at 1:500 for anti-human CD4, CD8, and CD68, and anti-mouse F4/80 Abs. stimulation of splenocytes, interferon (IFN)–producing cells were detected by ELISPOT from infected, but not uninfected NSG-A2-BLT mice. However, the levels of secreted IFN-, determined by ELISA, were not significantly elevated by antigenic stimulation. NSG-A2-BLT mice were susceptible to BCG infection as determined by higher lung bacillary load than the non-engrafted control NSG-A2 Aciclovir (Acyclovir) mice. BCG-infected NSG-A2-BLT mice developed lung lesions composed mostly of human macrophages and few human CD4+or CD8+T cells. The lesions did not resemble granulomas typical of Rabbit polyclonal to TrkB human TB. == Conclusions == Engrafted human immune cells in NSG-A2-BLT mice showed partial function of innate and adaptive immune systems culminating in antigen-specific T cell responses to mycobacterial infection. The lack of protection was associated with Aciclovir (Acyclovir) low IFN- levels and limited numbers of T cells recruited to the lesions. The NSG-A2-BLT mouse is capable of mounting a human immune response toM. tuberculosisin vivo but a quantitatively and possibly qualitatively enhanced effector response will be needed to improve the utility of this model for TB research. Keywords:Animal model, BCG, Tuberculosis, BLT mice, NSG mice == Background == Tuberculosis (TB), caused byMycobacterium tuberculosis(Mtb), Aciclovir (Acyclovir) remains a serious human health threat, killing 1.4 million people annually (Tuberculosis Fact Sheet, 2011, World Health Organization, Geneva, Switzerland). Despite numerous Aciclovir (Acyclovir) TB vaccine candidates being tested, the prospects for their success have dimmed following the failure of the MV85A TB vaccine in a recent clinical trial [1]. A major obstacle to TB vaccine development is the incomplete understanding of the human immune response to TB and the correlates of protection. Animal models, including mice, guinea pigs, rabbits and non-human primates have contributed to our current knowledge on Mtb-host interactions. The availability of genetically modified mice enabled researchers to identify crucial components of protective immunity including interferon (IFN)-, tumor necrosis factor (TNF)-, and interleukin (IL)-12 [2]. The roles of these factors have been verified in humans with mutations in the IFN- or IL-12 receptor genes and in patients treated with TNF- blockers [3,4]. Despite the usefulness of traditional animal models, they are criticized for not accurately reflecting human TB. The most critical difference lies in their homogenous susceptibility; 100% of mice, rabbits and guinea pigs infected with Aciclovir (Acyclovir) Mtb develop disease and eventually die with progressive lung pathology, while only 5-10% of Mtb-infected humans develop active TB disease [5]. Most infected individuals mount an effective immune response that maintains latency throughout their lifespan [5]. Latent TB infection is a unique feature of human TB, for which there is no optimal animal model. Non-human primates are capable of enforcing latency but nonetheless have a much higher rate of TB progression than humans, while rodent models are incapable of enforcing latency [6]. Another characteristic feature of human TB is the formation of organized, caseating granulomas with a macrophage core and a peripheral rim of lymphocytes [7]. Although TB lesions in mice contain macrophages and lymphocytes, they are poorly organized and generally not necrotic. Non-human primate (NHP) models mirror human TB pathology, but the use of NHP is limited by high cost and the lack of genetic models. These considerations emphasize the need for new and more tractable animal models that better reflect the unique features of human immunity to TB. Recent advances in humanized mice hold promise for an enhanced model of human immunity. Successful human cell engraftment requires an immunodeficient recipient. Advances in humanized mouse models have followed the generation of mouse strains with increasingly broader deficiency in host innate immunity and expression of human-specific cytokines and other factors. Attempts to engraft mice with human hematopoietic cells began with CB-17-Prkdcscid, severe combined.
