The immunology section of the course may seem very confusing to start off with, especially the when it comes to the adaptive immune system. Here is a brief summary that includes most of the information you'll need to know.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------
The Adaptive Immune SystemCells InvolvedStem cells differentiate into a type of 'parent' cell called a lymphoid progenitor in bone marrow. This cell is able to give rise to B and T lymphocytes. Cells that are intended to become B cells mature in the bone marrow itself whereas those that will become T cells migrate to the thymus and mature there. After maturation, all lymphocytes move to lymph organs (eg: spleen, lymph nodes) or circulate in the blood.
Humoral response: Involves B cells and antibody production
Directed against bacteria, viruses, and their toxins
Cell-mediated response: Involves T cells which have antigen-specific receptors on their surface
Directed against eukaryotic cells such as virus-infected cells, cancer cells, transplanted tissue, fungi
Action of B cellsB cells have antibodies (immunoglobins) specific to only one antigen on their surface. For each specific antigen, there are only very few B cells present. When confronted by an antigen, the B cells with the anitbody specific to that antigen multiply via clonal expansion.
Types of B cellsi. Plasma cells which produce antibodies which survive for a short time (each type of plasma cell can produce only one type of antibody).
ii. Memory B cells which remain for years if not a life time and initiate a quicker response on subsequent exposures to the same antigen.
The antibodies you need to know about are: IgG (these are the main type of antibody present in the humoral respone and can cross the placenta from mother to baby during gestation) and IgE (these are the antibodies involved in the allergic response). They work by attaching to the antigens on the surface of the pathogen, thus neutralising it and flagging it to be destroyed by macrophages. If many antibodies attach to a pathogen, a process called cross-linking can occur whereby the antibodies' effects are amplified.
Action of T cellsSimilarly to B cells, T cells are also antigen-specific and are only found in small numbers for each antigen. They then reproduce rapidly when they encounter the specific antigen.
Types of T cellsi. Helper T cells - recognise antigens and stimulate B cells or other T cells to reproduce. Also secrete a protein that stimulates other T cells and B cells
ii. Cytotoxic T cells - kills virus infected cells, cancer cells and transplanted tissue
iii. Memory T cells - formed during reproduction of T cells
iv. Suppressor T cells (don't need to know this one) - reduce or terminate immune response of other lymphocytes to restore stability
MOD EDIT: Removed All caps in title
Home
Help
Search
Login
