What is meant by Alloreactive?
(al″ō-rē-ak′tiv) [ allo- + reactive] Pert. to certain classes of T lymphocytes, immunologically reactive against a transplanted tissue or organ.
Why are T cells Alloreactive?
The prevailing explanation for alloreactivity is still that the response of allogeneic T cells to complexes of peptide and MHC (pMHC) is less peptide specific than is conventional (immune) T cell recognition of foreign pMHC complexes and that this so-called ‘degenerate’ response explains the high frequency of …
What is an allogeneic response?
Allogeneic responses are potent immune responses that cause allograft rejection. They are characteristically polyclonal, involving many TCR specificities, and are brought about by the activation of both naïve and preexisting, cross-reactive memory T cells.
What are allo antigens?
Medical Definition of alloantigen : a genetically determined antigen present in some but not all individuals of a species (as those of a particular blood group) and capable of inducing the production of an alloantibody by individuals which lack it. — called also isoantigen.
Are NK cells Alloreactive?
Importantly, infused NK cells were demonstrated ex vivo to be alloreactive by killing in vitro the recipient’s cells, including leukemia (5). Several biological factors, both of recipient and donor origin, may be implicated in the therapeutic effect of NK cells after infusion into AML patients.
What is allogeneic stimulation?
Abstract. THE theory of allogeneic stimulation1 postulates that transplantation antigens, such as H-2 in the mouse or H-LA in man, are not strong immunogens for allogeneic animals, but are rendered highly immunogenic when presented to the immune system in conjunction with an allogeneic stimulus.
What is allogeneic MHC?
Abstract. Direct allorecognition is the process by which donor-derived major histocompatibility complex (MHC)-peptide complexes, typically presented by donor-derived ‘passenger’ dendritic cells, are recognised directly by recipient T cells.
What is meant by the term allogeneic?
1 usually allogeneic : involving, derived from, or being individuals of the same species that are sufficiently unlike genetically to interact antigenically allogeneic stem cells allogeneic marrow transplantation — compare syngeneic. 2 allogenic : caused by the action or influence of abiotic environmental factors …
Are all T cells Alloreactive?
Key Points. A high frequency of T cells are alloreactive and are involved in transplant rejection and graft-versus-host disease (GVHD). Many alloreactive T cells are much more peptide specific than previously thought, and few if any recognize only the MHC molecule.
Why are Alloantibodies problematic for transplantation?
Preexisting alloantibodies to blood group antigens and polymorphic MHC antigens can cause rapid rejection of transplanted organs in a complement-dependent reaction that can occur within minutes of transplantation. This type of reaction is known as hyperacute graft rejection.
What is tissue transplantation?
A transplant is an organ, tissue or a group of cells removed from one person (the donor) and transplanted into another person (the recipient) or moved from one site to another in the same person. A skin graft is a common example of a transplant from one part of a person’s body to another part.
What does alloreactive mean in medical terms?
/al·lo·re·ac·tive/ (-re-ak´tiv) pertaining to the immune response in reaction to a transplanted allograft. alloreactive. Pert. to certain classes of T lymphocytes, immunologically reactive against a transplanted tissue or organ.
What is an alloreactive T cell clone?
We defined alloreactive T cell clones as those observed in at least 10 cells in the proliferated sample and unobserved in the uncultured T cell sample, or T cells whose frequency in the proliferated sample was at least ten-fold higher than in the uncultured T cell sample.
What is alloreactive T-cell activation?
Alloreactive T-cell activation requires antigen-specific engagement of the T-cell receptor with major histocompatibility complex molecules, followed by antigen nonspecific ligation of a variety of receptor–ligand combinations. Blockade of costimulation effectively prevents T-cell activation and so reduces the risk of allograft rejection.
How to study the alloreactive T cell repertoire?
It is our hypothesis that the alloreactive T cell repertoire can be studied by performing mixed lymphocyte reaction cultures , , followed by molecular analysis of clonotypes thus generated.