Complement and Reactants of Acute Phase of Inflammation in the Processes of Functional Activity of Non-Specific Resistance and Immunoregulation.

Complement system is a family comprising of 20 plasma and membrane proteins, acting in concord by cascade principle. The investigators display great interest to C4b-binding protein (C4bp) which is the main regulatory protein of complement system, regulating of C3 convertase activity in classical way of complement activation. The major regulatory function of C4bp is related to its interaction with activated form of the forth complement component, C4b. C4bp may also interact with one of pentraxins, serum amyloid P component (SAP) that inhibits complement-regulatory functions of C4bp. C4bp forms tight complexes with protein S and SAP. Pentraxin family (proteins with five-ray symmetry, such as C-reactive protein and SAP) became more numerous. Protein PTX3, synthesized by endothelial cells, macrophages and leukocytes, and considered to be local regulator of reaction of non-specific resistance in tissues; serum acute phase protein TSG-14; neuronal pentraxin - protein of cerebellum, hippocampus and brain cortex neurons, binding typoxin of snake venom; Narp (neuronal activity-regulated pentraxin) protein; apexin, acrosomal protein of spermatozoa; female hamster protein; pentraxin XL-PXN1 from Xenopus laevis - are all examples of new pentraxins. Pro-inflammatory cytokines, IL-1 and IL-6, may induce expression of pentraxin genes. Pentraxins are closely integrated not only to non-specific resistance, but to the system of immunoregulation and take part in its key events.