Adaptive Immunity Flashcards
(26 cards)
What are the hallmark features of adaptive immunity?
Specificity, tolerance, and memory.
What is the difference between an antigen and an immunogen?
An immunogen generates an immune response; an antigen binds to B or T cell receptors.
What does BCR stand for and what does it do?
B Cell Receptor; binds antigen directly.
What does TCR stand for and what does it do?
T Cell Receptor; binds antigen presented with MHC.
What is clonal expansion?
The rapid multiplication of B or T cells after activation.
What causes receptor diversity in B and T cells?
Somatic recombination of V, D, J gene segments.
What is somatic hypermutation?
Mutation in BCR genes to increase antibody affinity.
What are the isotypes of antibodies?
IgM, IgA, IgG, IgE, IgD.
Which cells present antigen via MHC class I?
All nucleated cells.
Which cells present antigen via MHC class II?
Professional antigen presenting cells (e.g., dendritic cells, macrophages, B cells).
What are the two signals required for T cell activation?
- Antigen recognition by TCR
- Co-stimulation (e.g., CD28 binding B7).
What is the immunological synapse?
Interface where T cell and APC interact, enabling activation.
What are T cell-independent antigens?
Antigens that activate B cells without T cell help (e.g., polysaccharides).
What are T cell-dependent antigens?
Protein antigens that require T cell help for B cell activation.
What does CD40 on B cells do?
Provides co-stimulatory signals for B cell activation.
What is immunological memory?
The ability of B and T cells to respond more rapidly upon re-exposure to an antigen.
What is the difference between primary and secondary immune responses?
Primary is slower and weaker; secondary is faster and stronger.
What is the goal of vaccination?
To induce immunological memory without causing disease.
What is central tolerance?
Elimination of self-reactive T and B cells during development.
What is peripheral tolerance?
Control of self-reactive mature lymphocytes via anergy, suppression, or deletion.
What is CTLA-4?
An inhibitory receptor on T cells that regulates immune activation.
What are regulatory T cells (Tregs)?
Cells that suppress immune responses and maintain tolerance.
What is autoimmunity?
Failure of tolerance leading to immune attack on self-tissues.
What are the four types of hypersensitivity?
Type I (IgE-mediated), Type II (antibody-mediated), Type III (immune complex), Type IV (T cell-mediated).
