Immunology 1 Flashcards
what are the main cells of the adaptive immune response, and how do they interact with the environment?
B and T lymphocytes - sense and respond to their environment via antigen specific cell surface receptors
two main types of immunity and how they differ
innate: no learning, no specificity or random diversity in cells. adaptive: can have a memory, infomration rich responses
non specific host defences: 4 main categories and examples
anatomic: skin and mucous membranes. physiologic: temperature, pH, chemical mediators. phacocytic/endocytic barriers. inflammatory barriers.
T cell receptors: how they bind to antigens
can’t bind free floating antigens (like B cells can), but only when they are chewed up into short peptides and presented on Class I (CD8) or Class II (CD4) MHC molecules.
CD4 vs 8? MHC Class?
4 = helper, MHC Class II. 8 = cytotoxic, MHC Class I
two main branches of the adaptive immune system?
humoral response (B cells making antibody), and the cellular response (T helper cells and T cytotoxic cells).
extracellular vs. intracellular microbes: which type of immune cells + MHC Class?
humoural immunity for extracellular pathogens. CD4 helper cells (Class II) for phagocytosed microbes. intracellular (Viruses) via CD8, Class I
virus infected cell: what happens + what cells are involved
viral proteins shown on outside of infected cell via Class I - cytotoxic CD8 T cell
CD4 regulatory/helper cells can see
presented on antigen presenting cells, which are the only ones that have Class II MHC. include macrophages + Bcells + dendritic cells
which antigens go on Class I vs II MHC?
endogenous antigens (viral peptides) on class I. exogenous (bacteria) on Class II.
what is critical for initiating adaptive immune response
movement of microbes/antigen into the draining lymph node - since lots of lymphocytes are in the lymph nodes and “sample” the antigens that are delivered there
what happens during maturation of B lymphocytes? when does it happen?
occurs in the absence of antigen: produces antigenically B cells so each expresses an antibody with single antigenic specificity
what happens during clonal selection of B lymphocytes
occurs when a given antigen binds to a B cell whose membrane bound antibody molecules are specific for epitopes of that antigen. then you get clonal expansion = get a bunch of memory and effector (plasma) B cells
what is the cellular basis of immunological memory?
clonal expansion of B or T cells with particular specificities and the production of long lived memory cells with this same specificity
antibodies: all consist of what structure containing what? two regions?
four chain structure with 2 heavy chains + 2 light chains. N terminus = variable region. C terminus = constant region
antibodies: what pairs with what and how is it stabilized?
each light chain pairs with one heavy chain: attached via interchain disulfide bonds. the two heavy chains also pair with each other, via interchain disulfide bonds
antibodies: each heavy/light chain made up of ___ of? stabilized by?
domains of ~110 aas with significant homology to one another, stabilized via intrachain disulfide bonds
light chain: what domains? what domains in heavy chain?
each light chain has 2 domains: VL (variable light) and CL (constant light). heavy chain has one variable domain, VH, and several constant domains numbered sequentially CH1, CH2, etc.
within the light and heavy chain variable regions, there are ___ regions of? forms what?
three regions of extreme variability = hypervariable regions. when folded, these 3 regions are brought together = antigen binding region (so total of 6 hypervariable loops. two of these sites per antibody
