Immunology Lecture 4. Flashcards
In what 7 ways does the secondary immune response differ from the first?
1 - shorter lag time 2 - higher rates of antibody synthesis 3- higher peak of antibody titer 4 - longer persistence of antibody 5 - IgG predominance 6 - higher affinity of antibody 7 - requires less antigen to begin
What is the difference between a toxin and a toxoid?
toxoid has toxicity inactivated/suppressed, while the immunogenicity is maintained - used to induce an immune response
What is the role of a B cell?
express surface immunoglobulin
What do B cells need to proliferate?
T cell help
What happens during clonal expansion of B cells?
increase in affinity by selective expansion -only the clones with the highest affinity will be stimulated ——> also make class switch to IgG from IgM and memory cells
What is the role of helper T-cells? (CD4)
limit B cells from making antibodies that attack self
What type of antigen do T-cells react to?
proteins or peptides on surface of presenting cell - these T cells will proliferate and stimulate B cells
What is the mechanism of a T-independent antigen?
cause a cross linking of the immunoglobulin on the B cell —> also through Toll receptors
What is an antigen presenting cell?
1 - initiate the interaction with antigen by endocytosis or phagocytosis, digest antigen for antigen presentation on MHC complex 2 - provide a co-stimulatory signal
What happens when there is presentation of antigen without co-stimulation?
nothing - NO IMMUNITY
What is the co-stimulatory signal?
B7
Are B-cells capable of processing antigen, expressing class II antigen, and expressing co-stimulators?
YES
What is MHC Class I?
presents endogenous antigens that originate in the cytoplasm (both self and foreign proteins) - on most cells
What is MHC Class II?
only on specialized immune cells - present exogenous proteins and are recognized by helper T cells
What two signals do T cells need for an antigen specific response?
antigen + MCH AND costimulator
