Dendritic cells (DCs) are a kind of the immune cells and as such it forms the part of the mammalian immune system. As far as the main process is concerned I must say that its main job is to process the antigen material and current it on the surface to other cells of the immune system, thus functioning as antigen-presenting cells.

The dendretic cells are present in the small quantities in the tissues that are in contact with the external environment which is mainly the skin and the inner lining of the stomach, lungs, nose and the intestine. We can also find them in the immature state of the blood.

As soon as they are activated they move to the lymphoid tissues where they react with the T cell and the B cells to initiate and shape the adaptive immune response. At definite expansion stages they grow branched projections, the dendrites that give the cell its name. However, these do not have any particular relation with neurons, which also have similar appendages. Undeveloped dendritic cells are also called veiled cells, in which case they possess large cytoplasmic ‘veils’ rather than dendrites.

History
Dendritic cells were first described by Paul Langerhans (Langerhans cells) in the late nineteenth century. It wasn’t until 1973, on the other hand, that the term “dendritic cells” was given by Ralph M. Steinman and Zanvil A. Cohn. In 2007 Steinman has been awarded the Albert Lasker Award for Basic Medical Research for his discovery.

Types of Dendritic cells
There are generally two kinds of the dendritic cells. I must say that the two kind of the dendritic cells are myeloid and plasmacytoid which is also called the lymphoid.

I would at first like to discuss the myeloid dendritic cells.

1. Myeloid dendritic cells
These are most similar to the monocytes. The MDC are made up of two subsets:

  • The more common mDC-1, which is a major stimulator of T cells.
  • The extremely rare mDC-2, which may have a function in fighting wound infection.

2. Plasmacytoid dendritic cells
These look like the plasma cells but have the certain characteristic of the myeloid dendritic cells.

  • Characteristic of the immature dendritic cells
  • High intracellular MHC II in the form of MIICs.
  • Expression of CD1a.
  • Active endocytosis for certain particulates and proteins; presence of FcgR and active phagocytosis.
  • Deficient T cell sensitization in vitro.
  • Low/absent adhesive and costimulatory molecules (CD40/54/58/80/86).
  • Low/absent CD25, CD83, p55, DEC-205, 2A1antigen.
  • Responsive to GM-CSF, but not M-CSF and G-CSF.
  • Maturation inhibited by IL-10.

Similarly there are some characteristic of the mature dendritic cells and I must tell you that these cells are really of great importance.