How do cells recognise each other?
The proteins, in particular glycoproteins, that protrude from the cell surface membrane are thought of to be important in cell recognition in a few ways. Similar sugar recognition sites can bind to each other to hold cells together. When tissues & organs form in embryonic development, this binding can be very significant. Glycoproteins also act as antigens which are recognised by white blood cells during specific responses to infection. An antigen is a substance that stimulates the production of an antibody when it enters the body. They are mainly chemicals on the surface of the cell like proteins, glycoproteins, and carbohydrates. They can also be toxins made by bacteria, or are whole microorganisms like bacteria or viruses.
Early evidence for cell recognition
Sponges are thought to be the most primitive of multicellular animals. Until 1765, people thought they were plants. They are made up of simple cells that group together, but don't move. The cells show some differentiation into several types concerned with food extraction and water flow, but they don't have organs or organ systems. Early in the 20th Century, H.V. Wilson split sponges into their individual cells by passing them through sieves. The cells started moving and kept moving until they met another cell. Groups of sponge cells formed, demonstrating cell recognition, and the clusters of sponge cells became new animals altogether.
Inflammation
Fever
Phagocytosis
Interferons
Interferon in medical treatments
Blah -_-