Immunology

…death from overwhelming opportunistic infection

(Born with it) Bruton’s disease Congenital thymic aplasia (Di George Syndrome) SCID - severe combined immune deficiency

Congenital agammaglobulinaemia Absence of B cells No germinal centres, small tonsils Maternal transfer of IgG protects baby for 6-9 months Treated by gamma-globulin injections • or patient dies from staph, strep + haemophilus influenzae

Absence of T cells, no secondary antibody response Patients cannot control viral infections Fetal thymus transplant required

T cells do not mature Adenosine deaminase deficiency Agammaglobulinaemia Extreme susceptibility to infection 2 year survival time w/out Bone Marrow transplant

Irradiation Cytotoxic drugs (suppress immune system) Glucocorticoids

HIV infecting + killing CD4 T cell = immune deficiency HIV lives inside T cells

Physical barriers (skin, mucus membrane) Innate immune system (consists of phagocytes -phagocytosis) Adaptive immune system (dependent on antigen receptors on lymphocytes; includes acquired)

ability to distinguish foreign, harmful antigenic threats (infection) from self - dependent on specific antigen receptors ability to then amplify that response by selectively expanding the clone of the crosslinked B cell or T cell + protective manner to protect against infection

Control blood-borne infection

Arise in bone marrow but mature in the thymus gland Start immune responses - have antigen specific T cell receptor (CD3) 2 populations of T cells • T helper • Cytotoxic T lymphocytes CD = cluster of differentiation = surface markers distinguishable by specific antibody reagents

Differentiate into plasma cells + secrete antibodies Function as a antigen-presenting cells (APCs)

Focus antigen onto the T + B cell antigen receptors causing a more powerful immune response

Immunoglobulin M (IgM) Immunoglobulin G (IgG) Immunoglobulin A (IgA) Immunoglobulin D (IgD) Immunoglobulin E (IgE)

Antibodies are also called immunoglobulins They co-purify with the globulin fraction of plasma There are 5 classes Each class has a specific receptor on its surface called Fc receptor. For phagocytosis to occur, antibodies crosslinked to antigen bind to Fc Region on phagocyte.

On basophils + mast cells They possess granules containing mediators e.g. histamine Mediators are released after contact with allergen

Act as chemical messengers

MHC is also known as Human Leukocyte Antigens (HLA) Function of MHC is to present antigen to T cells to distinguish between self + nonself