B cells Part I Flashcards
What is the purpose of B cells?
produce antibodies and control EXTRAcellular pathogens
How are B cells produced?
- hematopoietic stem cell in bone marrow
- lymphoid progenitor
- b-cell progenitor (naive b-cell enters circulation)
- B cell in peripheral secondary lymphoid tissues (gets activated)
what does bone marrow contain?
microenvironment/niches populated by hematopoietic cells
What can be found in bone marrow niches?
protein expression of cytokines, chemokine, and growth factors
What do cytokines do?
signalling through out immune response (ex. differentiation)
How do B cells obtain highly specific (unique) receptors?
gene rearrangement for different BCRs to recognize different epitopes
Where does gene rearrangement of b-cells occur?
bone marrow
Why does negative selection of b-cells occur?
self-antigens get eliminated/inactivated before they leave the bone marrow
What are the steps of b-cell development?
- BCR genes get reargued in DNA recombination
- negative selection + cell division
- naive b-cells enter circulation
What BCRs are on naive/mature b-cells?
all mature B cells express IgD and IgM with the same immunoglobulin specificity
(immature is only IgM)
Why do BCRs have the same specificity?
class of immunoglobulin is determined by heavy chain constant region which is encoded in genes
IgM is Cµ encoded
IgD is C(delta) encoded
What do naive B cells developing?
plasma cells, which can only secrete IgM
What is the main role of plasma cells?
secrete antibodies
