Adaptive Immuno Flashcards
What is the main cell type that controls the adaptive immune response? What makes them unique?
T cells (which are also crucial effector cells) are unique because they only recognize Ag bound to MHC.
What is SCID? What are the current therapeutic options?
Severe Combined Immuno-Deficiency “Bubble Boy”…Absence of B and T cells because lack enzyme ADA.
Treatments include: bone marrow transplant, gene therapy, and enzyme replacement therapy
What are the important components of the TCR complex?
Consists of
- TCR (with a constant and light region with Ag binding site)
- CD3
- Zeta: Both transmit signal into cell to proliferate
How is the TCR usually found in regards to the membrane? How is this different than B cells with their receptors for Ag?
It is only found as a cell surface receptor and its diversity is achieved through somatic recombination, like with the V region in Ab. However, unlike Ab, TCR cannot be found in the serum…they must be bound to the Tcell membrane
What cells are responsible for activating T cells?
APC such as dendritic, macrophages, and B cells
Where do B and T cells reside? Where are the common sites? Where does activation occur? How can there be a stronger activation?
In lymph nodes…neck, groin, and underarms. T cells are activated by APC in the lymph nodes and then migrate to site of infecion
Stronger activation=more APC binded to TCR= increase intracellular signaling.
What does it mean for a T cell to be activated?
It means that T cells will produce cytokines to increase presence of other leukocytes (CD4) or kill infected cells by ADCC or CTL mediated lysis.
What else is required in a T cell reaction with APC besides MHC/Ag, and CD40L?
Accessory molecules…so adhesion (CD4,CD8, CD2, LFA-1) co-stimulatory (CD28, CD40), or co-receptor molecules (CD4,CD8). Without them, no activation would occur=all APCs must have them
What is the main function of CD4 cells? What are the types of CD4 and which leukocytes do they have an effect on?
Increase immune response by secreting cytokines to activate other leukocytes about 65% of T cells.
(Th0 differentiates into)
Th1- macrophages IFN gamma
Th2-mast cells, eosinophils, plasma cells IL4
Th17- inflammation IL23 and IL17
What determines if Th0 becomes Th1 or Th2?
Nature and concentration of Ag and the cytokine environment
Where are Th17 located and what is their effect?
Located in GI tract and skin… recruit neutrophils to site of infection and promote inflammation
What is the main function of CD8 cells?
They bind with MHC and cause infected cell to die by releasing granules with perforin, enzymes, and protein toxins. This type of killing is Ag specific, controlled, and requires cell contact.
Where do T cells mature? What processes are involved in the maturation?
thymus… The thymocytes contain both CD4 and CD8 receptors…positive selection (to make sure TCR recognize MHC) and negative selection (to make sure TCR don’t recognize self as Ag)…end up expressing CD4 or 8 depending on which receptor reacted most tightly w/MHC
What is DiGeorge syndrome?
Large deletion from chromosome 22= recurrent infection, weakness/tiring, failure to thrive, and heart defect.
What is tolerance? What are the mechanisms?
Inability to make an immune response to an Ag
- Clonal deletion- loss of self reactive lymphocytes
- Clonal anergy- occurs in periphery (co-stimulatory absent)
- Immunological ignorance- interaction doesn’t lead to activation
