week 8 - adaptive immunity Flashcards
mostly definitions
define lymphocyte
a type of WBC that plays a critical role in the adaptive immune response. they are responsible for recognizing and responding to specific pathogens, infected cells, or foreign substances.
three main types
-B-cells
-T-cells
-NK cells
define B-cell
a type of lymphocyte that plays a key role in adaptive immunity by producing antibodies that target specific antigens on pathogens. some B-cells differentiate into plasma cells which produce antibodies and some differentiate into memory B-cells which provide long term immunity. B-cells develop and mature in the red bone marrow.
define humor
refers to any fluid in the body, such as blood, lymph, etc. in humoral immunity, B-cells are the primary line of defense because they produce antibodies that circulate in the body fluids.
define antibody-mediated immunity
aka humoral immunity; a type of adaptive immune response in which B-cells produces antibodies that target and neutralize specific antigens in body fluids.
*activated by extracellular pathogens (e.g., bacteria)
define cell-mediated immunity
a type of adaptive immune response that involves Tc cells directly attacking infected or abnormal cells. cell-mediated immunity targets intracellular pathogens (e.g., viruses), and involves Tc cells (directly destroying infected cells) and Th cells (which activate other immune cells).
define T-cell
a type of WBC that plays a role in adaptive immunity. they originate in the red bone marrow and mature in the thymus, where they differentiate into either Th cells or Tc cells.
define antigen
antigens are biochemical shapes that the immune system recognizes as belonging to a specific foreign invader. they are found on the surfaces of pathogens (e.g., bacteria, viruses, etc.) as well as other foreign substances (e.g., pollen, transplanted tissues, etc.). the specific region of an antigen that antibodies recognize is a 3D region called an epitope.
define epitope
the specific three-dimensional region on an antigen that is recognized and bound by antibody or a TCR.
what are 3 key characteristics of antigens that make them easy to identify?
1-shape: unique shape of epitopes makes them recognizable to immune cells
2-larger antigens are less likely to avoid detection, and they have more epitopes/binding sites
3-more complex antigens are easier to distinguish
exogenous antigens
antigens that are located on the outside of a cell (e.g. on surface of bacteria or viruses).
*activates the humoral immune response.
endogenous antigens
antigens that are produced inside the cells, but are transported to the cell surface (e.g. virus-infected cells or cancer cells).
*activates the cell-mediated immune response.
auto-antigens
self-antigens that are mistakenly recognized by the immune system as foreign. this triggers an autoimmune response, leading to tissue damage (e.g., rheumatoid arthritis).
BCR components
-2 heavy chains; variable region + constant region
-2 light chains; variable region and constant region
-antigen-binding site; formed by the variable regions
-transmembrane domain; anchors the BCR to the B-cell membrane
*the variable regions of both the heavy and light chains from the antigen-binding site. these regions are specifically shaped to a particular epitope on an antigen.
define plasma cell
a plasma cell is a type of activated B-cell that is responsible for producing and secreting large amounts of immunoglobulins (antibodies) that target specific antigens. they have a cytoplasm that is rich in rough ER for the mass production of immunoglobulins.
define antibodies
antibodies are proteins produced by plasma cells in response to a specific antigen. their primary function is to bind to antigens on pathogens, and help neutralize or mark them for destruction by other immune cells.
structure:
two heavy chains & two light chains, both with variable regions making up the antigen-binding site.
what are the 5 effects of antibodies?
1) neutralization; antibodies bind to pathogens or toxins, blocking toxic activity or attachment to host cells.
2) opsonization; antibodies coat the surface of a pathogen, making it easier for phagocytes to find.
3) agglutination; antibodies bind to multiple antigens, clumping them together, making them easier for immune cells to find.
4) oxidation; some antibodies catalyze the production of ROS, which can directly kill bacteria or damage their structures.
5) antibody-dependent cell-mediated cytotoxicity; antibodies mark infected or abnormal cells, signalling NK cells to bind and induce apoptosis through the release of toxic granules.
define TCR
a membrane bound protein found on the surface of T-cells. it is responsible for recognizing and binding to specific epitopes that are presented by MHC molecules on APCs.
define major histocompatibility complex
the MHC is a group of genes that encode proteins found on the surface of cells. MHC molecules present antigen fragments on the cell surface, allowing T-cells to detect and respond to infections or abnormal cells.
define APC (include 4 examples)
an APC is an immune cell that processes and presents antigen fragments on MHC molecules to activate T-cells.
professional APCs:
-macrophages
-dendritic cell; express MHC I and II
-B-cells
inadvertent APCs:
-tissue cells (when infected with an intracellular pathogen)
define autoimmune disease
a autoimmune disease is a condition in which the immune system mistakenly attacks the body’s own cells, tissues, or organs due to a failure to distinguish between autoantigens and foreign antigens. this leads to chronic inflammation and tissue damage.
major transfusion reaction
-when the recipient’s antibodies attack the donor RBCs due to mismatched ABO or Rh blood types.
-life threatening
minor transfusion reaction
-when donor plasma contains antibodies that recognize and bind to antigens on the recipient’s RBCs
-mild; fever, chills, rash
