A macrophage extends a semiliquid projection (a so-called pseudopodium) towards some bacteria in the foreground.
A macrophage extends a long, thin projection towards a foreign protein body.
Macrophages move more slowly than granulocytes but, on the other hand, are tougher and can handle larger prey. They are the armoured tanks of the immune system. Here they are in the process of enclosing microscopic glass fibres, which are also indigestible and can only be captured and transported away.
The Wars Within. Washington D.C.: National Geographic Society. bijschrift: One of mankind's greatest inorganic threats, asbestos fibers (left) are engulfed by a macrophage, which will probably die from its indigestible meal.
The structure of an MHC class I molecule, determined by X-ray crystallography.
Peptides are bound to MHC class I molecules by their ends. Peptides bind to MHC molecules through structurally related anchor residues.
MHC class II molecules resemble MHC class I molecules in structure.
Peptides are bound to MHC class II molecules by interactions along the length of the binding groove. Peptides that bind MHC class II molecules are variable in length and their anchor residues lie at various distances from the ends of the peptides.
Human MHC genes are highly polymorphic. In humans MHC genes are referred to as HLA (human leukocyte antigens). Expression of MHC genes is codominant. Polymorphism and polygeny both contribute to the diversity of MHC molecule expression by an individual.
Allelic variation occurs at specific sites within the MHC molecule. T-cell recognition of antigen is MHC-restricted.