What is the Role of the ‘T Cell’ in ‘B Cell’ Activation and Function?

Even though certain T cell independent antigens are capable of activating B cells, without T cells cooperation B cells cannot induce an effective and competent response. B and Th cells interaction is essential for proper activation and optimal function of B cells.

Binding of antigen with surface immunoglobulin of mature B cells initiates changes in membrane bound class II MHC molecules, and B7 Molecules that start appearing in large number to have better chances of TH cell interaction.

Through MHC class II molecules, B cells present the processed antigen peptide to TH cells, like an antigen presenting cell. The surface B_, molecule supports the reactions.

Generally antigen presentation through B cells occurs when antigen concentration is low and the macrophages, dendrite cells fail to catch and present them to TH cells.

Exposure of antigenic peptide over MHC class II molecules of B cells initiates Th cells interaction with B cells through them. The TH cells interaction with B cells induces release of different cytokines from TH cells that in turn initiates further activity in B cells.

CD19- It is functionally operative and transmits pleiotropic signals throughout the pro-B, pre-B, early B, and mature B cell stages of human B-cell ontogeny.

CD21-receptor for complement system,

CD22 – receptor is a sugar binding transmembrane protein, which specifically binds sialic acid with an immunoglobulin (Ig) domain located at its N-terminus. The presence of Ig domains makes CD22 a member of the immunoglobulin super family. (CD22 functions as an inhibitory receptor for B cell receptor (BCR) signaling.)

CD23 – is the “low affinity” receptor for IgE, an antibody isotype involved in allergy and resistance to parasites and is important in regulation of IgE levels.

B cell growth factor receptor – it is a receptor which binds to growth factor.

Histotope – The part of the MHC molecule recognized by the TH cell is referred as “Histotope”.

Desetope – The region of MHC that binds with antigen is “desetope”

Agretope – the region of antigen that binds with MHC is “Agretope”.

Epitope – Epitope is the region that binds with T cell receptor.

Paratope – Paratope is the T cell raptor region that binds with antigen “epitope”

Regulation of Antibody Production:

In a biological system regulation of any activity is equally important to initiation of the action. In the same way regulation of antibody production is also important to keep the body in healthy and normal condition.

Feedback mechanism, cross linking of receptors and idiotypic net works are some of the mechanisms through which antibody production is regulated.