Function
IgD's function has always been a puzzle in immunology since its discovery in 1964. IgD was recently found to be present in species from cartilaginous fish to human (probably with the exception of birds). This nearly ubiquitous appearance in species with an adaptive immune system demonstrates that IgD is as ancient as IgM and suggests the notion that IgD has important immunological functions.
In B cells, IgD's function is to signal the B cells to be activated. By being activated, they are ready to take part in the defense of the body in the immune system. During B-cell differentiation, IgM is the exclusive isotype expressed by immature B cells. IgD starts to be expressed when the B-cell exits the bone marrow to populate peripheral lymphoid tissues. When a B-cell reaches its mature state, it co-expresses both IgM and IgD. It is not well understood whether IgM and IgD antibodies are functionally different on B cells. Cδ Knockout mice (mice that have been genetically altered so that they do not produce IgD) have no major B-cell intrinsic defects. IgD may have some role in allergic reactions.
Recently, IgD was found to bind to basophils and mast cells and activate these cells to produce antimicrobial factors to participate in respiratory immune defense in humans. It also stimulates basophils to release B-cell homeostatic factors. This is consistent with the reduction in the number of peripheral B cells, reduced serum IgE level and defective primary IgG1 response in IgD knockout mice.
Read more about this topic: Immunoglobulin D
Famous quotes containing the word function:
“The more books we read, the clearer it becomes that the true function of a writer is to produce a masterpiece and that no other task is of any consequence.”
—Cyril Connolly (19031974)
“The press and politicians. A delicate relationship. Too close, and danger ensues. Too far apart and democracy itself cannot function without the essential exchange of information. Creative leaks, a discreet lunch, interchange in the Lobby, the art of the unattributable telephone call, late at night.”
—Howard Brenton (b. 1942)
“Any translation which intends to perform a transmitting function cannot transmit anything but informationhence, something inessential. This is the hallmark of bad translations.”
—Walter Benjamin (18921940)