Pathology Immunity

• The immune system consists of two arms: the innate immune response and the adaptive immune response.
• Innate immune cells include macrophages and granulocytes, which perform phagocytosis.
• Adaptive immune cells include B cells and T cells, which produce antibody isotypes and function through T cell activation.
• The immune system must perform four main tasks: immunological recognition, immune effector function, immune regulation, and immunological memory.
• Innate immune cells are produced in the bone marrow and are the first line of defense.
• The immune system has two arms: innate and adaptive.
• Adaptive immune cells include B cells, CD4+ T cells and CD8+ T cells.
• Innate immune cells include phagocytes and granulocytes.
• Antibodies can freely recognise antigen; T cells recognise antigen in the context of MHC molecules.
• Immune cells arise from stem cells in the bone marrow.
• Adaptive immune cells are produced in the bone marrow and are the second line of defense.
• Innate immune cells recognize an invading pathogen immediately but can be inefficient and may not have enough phagocytes for speedy containment of invading pathogens.
• Adaptive immunity amplifies the immune response to contain pathogens and makes the immune response more specific to particular pathogens.
• Secondary immune responses are faster and better because of T cells and B cells, which remember that the body has come into contact with the pathogen before.
• Vaccines harness the property of the immune response where B cells and T cells remember that the body has come into contact with the pathogen before.
• All cells are derived from the bone marrow in a process called haematopoiesis.
• All cells are derived from a common multipotent (or pluripotent) stem cell population.
• Stem cells divide to either a myeloid or a lymphoid progenitor.
• Immune cells are organised into structures known as lymphoid organs, with bone marrow being a primary lymphoid organ.
• Immune cell development occurs in primary lymphoid organs.
• Immune responses are generated in secondary lymphoid organs.
• Secondary lymphoid organs include the spleen, adenoids, tonsils, lymphatic system, Peyer’s patches, and the thymus.
• Cytotoxic CD8+ T cells recognize and lyse virally infected or tumour cells.
• Cytotoxic T cells express adhesion molecule CD8 and respond to intracellular antigen.
• The T cell receptor is unable to recognise antigen in the same way as the B cell receptor on B cells.
• The T cell receptor only recognises antigens in the form of peptides bound to MHC molecules.
• Primary lymphoid organs include the bone marrow and the thymus.
• The MHC molecules bind peptide fragments from pathogens and display them to T cells.
• B cells have surface antibodies (also known as the B cell receptor) on their surface.
• The function of CD4+ T cells is to provide "help" for effector cells of the immune system, hence the name T helper cells.
• Memory B cells confer immunological memory, ensuring that secondary response to pathogen is rapid.
• T cells recognise antigen via the T cell receptor.
• Antibodies are not immunogenic and need to be coupled to a carrier to elicit an immune response.
• Antibody is produced by B cells.
• All T cells express the T cell receptor (TCR).
• CD4+ T cells promote or help: Macrophage activation (phagocytosis), B cells to produce antibodies.
• The variable (red) portion of the surface antibody recognises foreign antigen.
• A single B cell has approximately 150,000 molecules of a single antibody (B cell receptor) on its surface.
• T cells are produced in bone marrow and mature in the thymus.
• CD4+ T cells respond to exogenous antigen.