immunology 3,4 Flashcards
describe general features of adaptive/acquired immune system
specific resistance to infection, results in development of immunologic memory, long term protection, recall ability, develops after infection or vaccination, leads to cell mediated (T cells) and humoral (B cells) immunity
what is immunocompetence
ability of an immune system to resist and control infections, babys havent encountered foreign cells yet but they have the potential to respond to them
what is immunodeficinecy
babies born with partially formed thymus gland or removed/unable to fight of infections effectively
where are lymphocytes made
bone marrow
when does lymphocyte development begin
foetal development
for specific immune responses to function, need lymphocytes that…
-mature into cells with defined roles and functions
-encounter and responds to antigens
-activate other cells and production of antibodies
adaptive immunity divides into 2 events which are
antigen independent- cells differentiate from stem cells maturing in either bone marrow or thymus, mature cells reside in lymphoid organs/nodes/tissue
antigen dependent- cells interact with antigens and APCs, activation of T and B cells and cell mediated immunity and humoral immunity
what does APC stand for
antigen presenting cells
what is the major histocompatibility complex (MHC) and where are they found
(also called human leukocyte antigen system)
genetic locus encoding for glycoproteins/group of genes that code for proteins found on surface of cells that help immune system recognise foreign substances, essential for antigen recognition by T cells
found on all nucleated cells and WBCs
describe the different classes of MHCs
class I=on all nucleated cells, display unique self antigens and foreign antigens to T cells, regulate immune response and permit recognition of self molecules
class II=only on certain APC, encode immunoregulatory receptors, present abnormal or non self pathogen antigens for T cell activation, receptor expressed by APCs/B cells/dendritic cells (adaptive)/macrophages (innate)
describe what happens in antigen independent period
lymphocyte development
- subset of stem cells in bone marrow develop into WBCs
- continuous cell division of lymphocyte in embryo
- genetic changes and rearrangements take place
- cell differentiation into T and B cells
- genetically distinct cells produced with antigen specificity
-begins without any antigen interaction, preprogrammed
what is clonal deletion
removing immature lymphocytes that interact with antigens during maturation or lymphocytes that react to self MHC
describe what happens in the antigen dependent period
clonal selection
- antigen interaction with clone (via T cell receptor and MHC antigen)
- mitosis stimulated
- population of lymphocytes formed (specific for the antigen encountered)
- immune response now increased
similarities and differences between T cell receptors and immunoglobulins
similarities- genetic rearrangements and assortments, variable and constant regions, insert and transition through cell membrane, antigen binding sites formed by a pair or parallel polypeptides
differences- TCR smaller, TCR are embedded, immunoglobulins are secreted
what are clusters of differentiation receptors (CD)
T cells other receptors, added to membrane during cell maturation, increases varied and specific functions of T cells, interacts with MHC on WBCs
functions- cell receptors/adhesion/communication
CD4 on T helper cells
CD8 on cytotoxic T cells
