Mod3: Immunity Flashcards
Normal function of T-lymphocytes differ from B-lymphocytres how
B cells produce antibodies, form recognizable complexes for immune system
T cells- recognizes antigen outside of cell, can attack
Humoral immunity function
Stimulated by
Provides protection against (5)
B-cells stimulated by IL4
Provides immunity against viral, toxin diseases, pneumococci, meningococcal, haemophilus diseases
Cell mediated immunity
T-cells
Against intracellular bacteria/viruses
Defense w CA, fungal, parasitic infections
Responsible for organ transplant rejection
Active acquired immunity
Produced by host after exposure to antigen or immunization
slower acting, long lived, improves w repeat exposure
Passive acquired immunity
Acquired via the transfer of antibodies, or T-cells to the recipient
Natural-fetus
Artificial-immediate,2 wks, tb,rabies,tetanus,hepatitis,snake bite
Self antigen
Production of
Tolerable?
Regulated by
Immunogens=immune response=production of antibodies/Tcells
Most can tolerate own Tcells
Regulated by T regulatory cells
B-lymphocyte
IgA
Main ig in secretions and mucous membranes
Prevents attachment of microorganisms to mucous membrane
B-lymphocyte
IgM
Produced early in primary immune response
High level=recent infection
B-lymphocyte IgG
Binds with viruses, bacteria, toxins Activates complement and binds to macrophages Primary antigen in secondary response Crosses placenta Provide long lasting immunity
B-Lymphocyte IgE
Binds to mast cells, eosinophils and basophils
Involved in parasitic and hypersensitive rxn’s
T-lymphocytes: T-cytotoxic cells
Killer T, CD8, T8 cells
Kill virus infected, tumor, and allograft cells directly thru release of cytotoxic chemicals destroying membrane or =apoptosis
T-lymphocytes
NK Killer
Contain granules that recognize, attack and kill virus infected or cancerous cells
Inhibitory/activation receptors allow differentiation infected/normal cells
Produces cytokines that kill
T-lymphocytes
T-helper
TH1,TH2
Secretes cytokines stimulating differentiation of B to plasma cells Activate macrophages(B-cells, Cytotoxic Tcells + other CD4 cells) Release lymphokines=begins inflammatory process Mediate delayed hypersensitivity rxn’s
How do B lymphocytes recognize and process antigens
Bcell receptor on surface recognize antigen
L4 -> B-cells into plasma cells= antibodies/memory B-cells
antibodies bind to antigen =antigen-antibody complexes
Memory B-cells act during secondaryresponse
How do T lymphocytes recognize and process antigens
Antigen enters->Macrophage (or other APC) engulfs antigen ->antigen
expressed on MHC class II -> secretes IL 1 to attract CD4 cells ->presents it to CD4-cells ->CD4 differentiates into Th1 and Th2->Th1 releases IL2 -> activated cytotoxic T-cells (Tc) ->Tc receptor connects with MHC class I receptor on invader-> cytotoxic chemicals released ->invader killed
Th2 releases IL4 → activates the humoral immune system
Purpose and process of primary immune response
Response in 5-7 days
Bcell differentiation, clonal selection,processing/presenting antigens, Bcell TH cell interaction must occur
^igM initial then ^igG in second
Purpose and process of secondary immune response (2nd exposure)
anamnestic immune response. IgM levels rise during this response, but IgG levels rise much more than in a primary immune response
Age related changes in immune system
60+ decreased T- cell activity vThymus size= vT-cell differentiation T-cell numbers do not decrease. B-cells produce less antibodies vAmount of circulating memory B-cells ^circulation of autoantibodies
Fetal immune function
vPhagocytic activity, antibody production, complement activity
last trimester-fetus can mount a primary immune response and produce IgM antibodies but they are unable to produce a significant amount of IgG antibodies
unable to produce IgA antibodies.
mother’s antibodies are transported across the placenta and provide protection
Neonatal immune function
At birth IgG levels in the umbilical cord blood is near adult levels but then drops off after the cord is cut. Antibody levels reach a minimum point at 5-6 months post birth
Cause recurrent resp infections
Antigen presenting cells
B-lymphocytes
macrophages, dendriticncells
Allergens
Antigens=allergic response
Antibodies
Immunoglobulin Yshaped
Coats pathogen->forms antibody complex->activates complement cascade
T cells differentiated by
expression of antigen on their cell “cluster of differentiation”
