The different threshold of activation for memory T cells compared to that of naïve T cells makes them resistant to immunomodulation, thus representing a barrier to tolerance. Recently it has been demonstrated that homeostatic proliferation and heterologous immunity represent two naturally occurring and distinct processes that can generate memory T cells. Homeostatic proliferation refers to the process by which, in a lymphodeficient host, normal T cells 'spontaneously' proliferate in response to self-MHC-peptide complexes. Heterologous immunity refers to a process in which a response to one or more infectious agents generates effector/memory T cells with cross-reactive specificities. Recent new studies have defined the importance of these processes in transplantation models and implicated strategies to induce transplantation tolerance.
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http://dx.doi.org/10.1016/j.coi.2004.07.007 | DOI Listing |
Vaccines (Basel)
January 2025
International Centre for Diarrhoeal Disease Research, Bangladesh, 68, Shaheed Tajuddin Ahmed Sarani, Dhaka 1212, Bangladesh.
Background: Vaccination has played a crucial role in mitigating the spread of COVID-19 and reducing its severe outcomes. While over 90% of Bangladesh's population has received at least one COVID-19 vaccine dose, the comparative effectiveness of homologous versus heterologous booster strategies, along with the complex interplay of factors within the population, remains understudied. This study aimed to compare antibody responses between these booster approaches.
View Article and Find Full Text PDFRev Inst Med Trop Sao Paulo
January 2025
Universidade de São Paulo, Faculdade de Medicina, Hospital das Clínicas, Divisão de Clínica de Moléstias Infecciosas e Parasitárias, Laboratório de Investigação Médica em Imunologia (LIM-48), SSão Paulo, São Paulo, Brazil.
Immunocompromised individuals were considered high-risk for severe disease due to SARS COV-2 infection. This study aimed to describe the safety of two doses of COVID-19 adsorbed inactivated vaccine (CoronaVac; Sinovac/Butantan), followed by additional doses of mRNA BNT162b2 (Pfizer/BioNTech) in immunocompromised (IC) adults, compared to immunocompetent/healthy (H) individuals. This phase 4, multicenter, open label study included solid organ transplant and hematopoietic stem cell transplant recipients, cancer patients and people with inborn errors of immunity with defects in antibody production, rheumatic, end-stage chronic kidney or liver disease, who were enrolled in the IC group.
View Article and Find Full Text PDFDengue virus (DENV) remains a significant public health threat in tropical and subtropical regions, with effective antiviral treatments and vaccines still not fully established despite extensive research. A critical aspect of vaccine development for DENV involves selecting proteins from both structural and non-structural regions of the virus to activate humoral and cellular immune responses effectively. In this study, we developed a novel vaccine for dengue virus serotype 2 (DENV2) using a heterologous Prime-Boost strategy that combines an adenoviral vector (Ad) with subunit vaccines.
View Article and Find Full Text PDFXenotransplantation
January 2025
Beijing Key Laboratory of Preclinical Research and Evaluation for Cardiovascular Implant Materials, Animal Experimental Centre, National Centre for Cardiovascular Disease, Department of Cardiac Surgery, Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Organ transplants are used to treat many end-stage diseases, but a shortage of donors means many patients cannot be treated. Xenogeneic organs have become an important part of filling the donor gap. Many current studies of kidney, heart, and liver xenotransplantation have used gene-edited pig organs on brain-dead recipients.
View Article and Find Full Text PDFElife
January 2025
Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, Israel.
Trained immunity (TI) is the process wherein innate immune cells gain functional memory upon exposure to specific ligands or pathogens, leading to augmented inflammatory responses and pathogen clearance upon secondary exposure. While the differentiation of hematopoietic stem cells (HSCs) and reprogramming of bone marrow (BM) progenitors are well-established mechanisms underpinning durable TI protection, remodeling of the cellular architecture within the tissue during TI remains underexplored. Here, we study the effects of peritoneal Bacillus Calmette-Guérin (BCG) administration to find TI-mediated protection in the spleen against a subsequent heterologous infection by the Gram-negative pathogen Typhimurium (.
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