4.1.5

the foreign chemical markers on the surface of pathogens are called antigens. Antigens are how we identify a pathogen as foreign. Antigens are proteins or glycoproteins . Antigens are specific to the organism.  Opsonins are proteins. opsonins attach to the antigens on the surface of the pathogen.  opsonins are a type of antibody. opsonins aren't all specific. opsonins allow the phagocytic cells bind and engulf the pathogen. the most common phagocytes are called neutrophils neutrophils have a multi-lobed nucleus neutrophils are manufactured in the bone marrow neutrophils can be found traveling in the blood and in the tissue fluid neutrophils are short lived but released in large numbers neutrophils contain a large number of lysosomes dead neutrophils can collect in an area of infection causing pus macrophages are larger than neutrophils macrophages are manufactured in the bone marrow macrophages travel in the blood as monocytes monocytes mature in the lymph nodes forming macrophages  macrophages engulf pathogens but save their antigen and put it on their cell surface  after becoming the antigen presenting cell it travels in the blood spreading the recognition of a threat APCs have a special protein complex that ensures they don't get mistaken for a foreign cell        

T-lymphocytes can differentiate into: T-helper cells  T-killer cells T-memory cells t-regulator cells T-helper cells release cytokines that stimulate the B cells to develop and stimulate phagocytosis via phagocytes T-killer cells