monocytes
Cells of the monocytic lineage play an essential role in initiating and maintaining immune responses by acting as antigen-presenting cells. They process and present antigenic peptides via and express costimulatory molecules such as b7.1 and B7.2. Antigen presenting cells can internalize antigen by phagocytosis, endocytosis, or both.
Monocytes circulate in the blood stream for about 8 hours during which time they enlarge, migrate into the tissues and differentiate into specific tissue macrophages which with the neutrophils are the main phagocytes in the body. Monocytes also give rise to which are also migratory cells that can ingest foreign substances but which have a main role as presenters of foreign antigens to lymphoctyes.
Identification of:
Monocytes can be stained for CD14 and CD11b.
Factors secreted by Monocytes:
–secretion of TNF-alpha: Monocytes are most notably known for the production of TNF-alpha, one of the most potent inflammatory cyotokines.
Activation of:
Monocytes are activated via binidng of C3a and C5a to their responstive receptors. (see components of the complement system)