Antigen-receptors, MHC, and antigen-presentation Flashcards
What are antigen-receptors?
Specialized receptors on B and T cells that recognize specific antigens, triggering immune responses.
What is MHC (Major Histocompatibility Complex)?
Molecules on the surface of cells that present antigens to T cells, aiding in the recognition of pathogens or infected cells.
What does MHC Class I do?
Presents endogenous antigens (e.g., from viruses) to CD8+ cytotoxic T cells.
What does MHC Class II do?
Presents exogenous antigens (e.g., from bacteria) to CD4+ helper T cells.
What is antigen presentation?
The process by which cells display antigen fragments on their MHC molecules to activate T cells.
What is a BCR (B-cell receptor)?
A membrane-bound antibody on B cells that binds to specific antigens, initiating an immune response.
What is a TCR (T-cell receptor)?
A receptor on T cells that recognizes processed antigens presented by MHC molecules on the surface of other cells.
What is cross-presentation?
The process where dendritic cells present exogenous antigens on MHC Class I molecules to activate CD8+ T cells.
What are endogenous antigens?
Antigens originating from inside the cell, such as viral proteins, presented on MHC Class I molecules.
What are exogenous antigens?
Antigens from outside the cell, such as bacterial proteins, presented on MHC Class II molecules.
What is antigen-processing?
The breakdown of proteins into smaller peptides for presentation on MHC molecules.
What are CD8+ T cells?
Cytotoxic T cells that recognize antigens presented by MHC Class I molecules and kill infected cells.
What are CD4+ T cells?
Helper T cells that recognize antigens presented by MHC Class II molecules and assist other immune cells in responding.
What are APCs (Antigen-presenting cells)?
Cells like dendritic cells, macrophages, and B cells that present antigens to T cells.
What are dendritic cells?
The most potent APCs, crucial for initiating immune responses by presenting antigens to T cells.
What are cytotoxic T cells (CD8+)?
T cells that kill infected or cancerous cells upon recognition of antigens on MHC Class I molecules.
What are helper T cells (CD4+)?
T cells that activate other immune cells, such as B cells and cytotoxic T cells, in response to antigens presented on MHC Class II.
What is a peptide-MHC complex?
The combination of an antigenic peptide and an MHC molecule that is recognized by T-cell receptors.
What is clonal selection?
The process by which a specific T or B cell is selected for activation and proliferation upon recognition of its specific antigen.
What is an immune synapse?
The interface between an antigen-presenting cell and a T cell, where antigen recognition and signal transduction occur.
What is T-cell activation?
The process by which T cells become activated upon binding to antigen-MHC complexes on APCs.
What is B-cell activation?
The process by which B cells become activated after binding an antigen with their BCR, leading to antibody production.
What is MHC polymorphism?
The genetic diversity in MHC molecules that allows the immune system to recognize a wide variety of antigens.
What is antigenic variation?
The ability of pathogens to alter their surface antigens to evade immune recognition.
What is self-tolerance?
The ability of the immune system to recognize and ignore the body’s own cells to prevent autoimmunity.
What are superantigens?
Pathogen-derived proteins that can activate a large number of T cells by binding to the MHC Class II molecules and TCRs, leading to excessive immune activation.