Adaptive Immunity - T Cells Flashcards
What is the role of specific immunity?
Recognise and respond to pathogens/danger but must discriminate ‘non self’ from ‘self’
What does failure of specific immunity lead to?
Death from infectious disease
Autoimmune diseases
What are the main types of T lymphocytes and their function?
Cytotoxic
surface marker: CD8
secreted product: perforins, granzmes, cytokines
target cell: any nucleated cells
effect: kill abnormal or virus infected cells
Th1
surface marker: CD4
secreted product: cytokines
target cell: macrophages
effect: stimulus/activation of immune cells
Th2
surface marker: CD4
secreted product: cytokines
target cell: B cells
effect: proliferation of b lympphocytes and secretion of antibodies
Regulatory
surface marker: CD4
secreted product: b cells
target cell: T cells, B cells & macrophages
effect: inhibition (of immune system)
Do antibodies deal with antigens outside or inside the cell?
Antibodies typically deal with antigens outside of the cell.
If antibodies cannot detect pathogens inside the cell, how are they eliminated?
By CD8+ cytotoxic T cells
How do cytotoxic T cells eliminate pathogens?
T cells are arise in the bone marrow and are then matured in the thymus where they become activated.
What is a native T cell?
A T cell before it comes into contact with its specific antigen
How do cytotoxic T cells and T-helper cells recognise pathogens?
Via antigen presentation on the cells surface by major histocompatibility complex (MHC) found on all nucleated cells.
MHC molecules have special grooves that antigen fragments slot into.
T cells recognise linear peptide antigens which are bound to MHC molecules on the cells surface
What is the difference in structure between immuoglobulins and T cell receptors?
Both have constant and variable regions however the TCR remains membrane-bound - not secreted to do their job
What are the forms of T cell receptors
alpha-beta = majority 90-99% of T cells
gamma-delta - 1-10% of T cells
How can T cells recognise so many antigens?
Diversity is generated by ‘mixing and matching’ (shuffling, cutting and pasting) gene segments within 4 genes that encode TCRs - alpha, beta, gamma and delta.
What is the role of recombinant activating genes (RAG)?
recombinant activating genes - encode parts of a protein complex that plays important roles in the rearrangement and recombination of the genes encoding immunoglobulin and T cell receptor molecules.
