Antibodies; B Cells Flashcards
What are the dual functions of B cells?
- Transform into plasma cells and secrete antibodies
- Present processed antigens to T cells
How do antibodies kill antigens?
Agglutination (binding) and neutralization (inactivation) –> this complex is recognized by macrophages, which phagocytose and degrade it
What happens when a B cell becomes tumorgenic?
Myeloma (cancer of plasma cells) –> osteoclasts
What happens when a B cell produces antibodies against self-antigens?
Autoimmune Diseases
What occurs in the primary lymphoid organ?
B-cell development; no antigen interactions. Bone marrow, germinal centers
What occurs in the secondary lymphoid organ?
B cells interact with antigens; differentiate into plasma cells or memory cells. Bone marrow, bursa, lymph
Why can some B cells recognize free (non membrane-bound antigens)?
Their receptors do not require binding to MHCs (of APCs)
What class of antibody is a cell surface-receptor of mature B cells?
IgD
What class of antibody appears first in systemic circulation and is largest in size?
IgM
What class of antibody is most abundant, smallest in size, can penetrate blood vessels and placenta, and performs opsonization?
IgG
What class of antibody causes vasoconstriction and bronchoconstriction (allergic rxns)?
IgE
What class of antibody is found on mucosal surfaces?
IgA
Describe the structure of an antibody.
4 chains - 2 short/light chains and 2 long/heavy chains. 1 light + 1 heavy bonded via glycosidic bond on either side of hinge region (none in IgM). Top portion = “fragment antigen binding (Fab)” region, where a specific “seat” is created for its corresponding antigen.
What is maintained between primary immune response to secondary immune response?
The specificity/Fab region of antibody
What area of an antibody allows the immune system to create a specific BCP for every possible antigen?
recombination of genes in the variable region
