Please enable JavaScript.
Coggle requires JavaScript to display documents.
B- LYMPHOCYTES, SANDHYA A 191822016 - Coggle Diagram
B- LYMPHOCYTES
DEFINITION
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system by secreting antibodies
DEVELOPMENT
-
HSCs first differentiate into multipotent progenitor (MPP) cells, then common lymphoid progenitor (CLP) cells.
From here, their development into B cells occurs in several stages (shown in image to the right), each marked by various gene expression patterns and immunoglobulin H chain and L chain gene loci arrangements, the latter due to B cells undergoing V(D)J recombination as they develop
ACTIVATION
B cell activation occurs in the secondary lymphoid organs (SLOs), such as the spleen and lymph nodes.
After B cells mature in the bone marrow, they migrate through the blood to SLOs, which receive a constant supply of antigen through circulating lymph.
At the SLO, B cell activation begins when the B cell binds to an antigen via its BCR.
At the SLO, B cell activation begins when the B cell binds to an antigen via its BCR.
When a BCR binds an antigen tagged with a fragment of the C3 complement protein, CD21 binds the C3 fragment, co-ligates with the bound BCR, and signals are transduced through CD19 and CD81 to lower the activation threshold of the cell
-
-
Memory B cell activation
Memory B cell activation begins with the detection and binding of their target antigen, which is shared by their parent B cell
Some memory B cells can be activated without T cell help, such as certain virus-specific memory B cells, but others need T cell help
TYPES
Plasmablast - A short-lived, proliferating antibody-secreting cell arising from B cell differentiation.Plasmablasts are generated early in an infection and their antibodies tend to have a weaker affinity towards their target antigen compared to plasma cell.
Plasma cell - A long-lived, non-proliferating antibody-secreting cell arising from B cell differentiation.There is evidence that B cells first differentiate into a plasmablast-like cell, then differentiate into a plasma cell.
Lymphoplasmacytoid cell - A cell with a mixture of B lymphocyte and plasma cell morphological features that is thought to be closely related to or a subtype of plasma cells.
Memory B cell - Dormant B cell arising from B cell differentiation.Their function is to circulate through the body and initiate a stronger, more rapid antibody response (known as the anamnestic secondary antibody response) if they detect the antigen that had activated their parent B cell (memory B cells and their parent B cells share the same BCR, thus they detect the same antigen).
-
B-1 cell - Arises from a developmental pathway different from FO B cells and MZ B cells. In mice, they predominantly populate the peritoneal cavity and pleural cavity, generate natural antibodies (antibodies produced without infection), defend against mucosal pathogens, and primarily exhibit T cell-independent activation
Regulatory B (Breg) cell - An immunosuppressive B cell type that stops the expansion of pathogenic, pro-inflammatory lymphocytes through the secretion of IL-10, IL-35, and TGF-β. Also, it promotes the generation of regulatory T (Treg) cells by directly interacting with T cells to skew their differentiation towards Tregs
B-CELL RELATED PATHOLOGY
Autoimmune disease can result from abnormal B cell recognition of self-antigens followed by the production of autoantibodies.
-
-
-
-
-
FIGHTING INFECTION
B-cells fight bacteria and viruses by making Y-shaped proteins called antibodies, which are specific to each pathogen and are able to lock onto the surface of an invading cell and mark it for destruction by other immune cells.
-
IMPORTANCE
B-cells are as important as T-cells and are much more than just a final clean-up crew. They make important molecules called antibodies. These molecules trap specific invading viruses and bacteria. Without this line of defense, your body would not be able to finish fighting most infections.
-