B Cells and diseases Flashcards
What is the basic structure of an antibody?
Antibodies consist of two heavy chains and two light chains, with variable and constant regions.
What are the major steps in B-cell development?
B cells develop in the bone marrow, undergoing gene rearrangement to express unique B-cell receptors (BCRs).
What is V(D)J recombination?
A process in which B-cell receptor genes are rearranged to create diverse antigen-binding sites.
How do B cells recognize antigens?
Through surface-bound immunoglobulin (BCR) that binds specific antigens.
What happens after a B cell binds an antigen?
The B cell processes and presents the antigen to T cells, receiving activation signals to differentiate.
What is isotype switching?
A process where B cells change their antibody class (e.g., IgM to IgG) while maintaining antigen specificity.
What is somatic hypermutation?
A mechanism that introduces mutations in the antibody variable region to improve antigen binding.
What is affinity maturation?
The process by which B cells with higher antigen affinity are selected for survival and expansion.
What are primary immunodeficiencies (PIDs)?
Genetic disorders affecting immune function, often resulting in recurrent infections.
What is X-linked agammaglobulinemia (XLA)?
A PID caused by a mutation in BTK, leading to absent B cells and low antibody levels.
How is Common Variable Immunodeficiency (CVID) diagnosed?
By measuring low immunoglobulin levels and poor vaccine responses.
What are monoclonal antibodies?
Lab-engineered antibodies designed to target specific antigens for therapeutic use.
How are monoclonal antibodies used in therapy?
They treat diseases like cancer and autoimmune disorders by targeting specific proteins.
What is immunoglobulin replacement therapy (IRT)?
A treatment for antibody deficiencies using intravenous or subcutaneous IgG.
Why is antibody diversity important?
It allows the immune system to recognize a vast array of pathogens, improving adaptive immunity.
What are the 4 ways of generating BCR diversity
- Random selection & rearrangement of V(D)J minigene segments
- Independant rearrangement at heavy and light chain loci
- Imprecision of junctions - random insertion of nucleotides at junction regions mediated by TdT
- Somatic hypermutation and affinity maturation: single point mutations in hypervariable regions & selection of highest affinity binders
