[Determination of proteinase activity of complement system by immunoenzyme methods].

Modern ELISA for determination of functional activity of component C2 and factors B and D, proteinases of a complement system, and component C3, substrate C3-convertases, key complex enzymes of the complement, have been developed. Essential feature of C3-convertases classical (C4bC2a) and alternative (C3bBb) pathways of the complement activation is that their substrate C3 after proteolytic cleavage is converted into C3b, carrying on the surface thioester covalent bond linking C3b with nucleophilic acceptors that results in immobilization of this proteolytic product near the activating enzyme. Cascade character of an activation of complement system allows to create artificial deficit of separate components in the experimental system and to determine (by ELISA) covalently immobilized component C3 during activation, and also to determine functional activity of any of pre-exhausted components.

[A drop of mink complement kills a mouse].

The phenomenon of fast death of mice after parenteral administration of mink serum was explained by high activity of mink complement in particular by unusually high activity of its alternative pathway of activation. The presence of antibodies to mouse erythrocytes in mink serum was necessary precondition for their lysis under action of mink complement by classical and alternative pathways. However, removal of these antibodies resulting in cancellation of hemolysis did not effect toxicity of mink serum for nice in vivo.

[Inhibition of binding of activated compliment component C4b with its target].

The inhibition of covalent binding of the nascent C4b fragment of the human complement component to its natural target, immunoglobulin G, was studied. To this end, an immunoenzyme system was developed. In this ELISA method, the complement was activated on the sorbed IgG molecules and the resulting nascent C4b fragment acylated IgG or interacted with a competitive inhibitor added to the system.

Action of nonviral gene delivery vectors on human complement system: low anticomplementary activity of lipoplexes based on lacZ plasmid and phospholipid/oligocation liposomes.

A simple test-system has been developed for the first time in order to detect the ability of effectors (lipoplexes) to activate the complement system in an antibody-independent manner to serve as acceptors of nascent C4b and to inhibit formation of the key enzyme of complement, C3-convertase. The effect of plasmid DNA (pCMV-SPORT-LacZ), negatively charged cardiolipin (CL), neutral phosphatidylcholine (PC) vesicles and their lipoplexes, on the complement system was studied using the method developed. It was revealed that PC vesicles did not affect the complement system, while CL vesicles manifested low activation.

[Inborn deficiency of complement C4A and C4B isotypes in persons infected with Chlamydia].

The difference in the functional activity of the isotypes A and B of component C4 of human complement was used to determine their ratio to detect the inherited deficiency of the isotypes. The frequency of deficiency in healthy persons blood donors was equal for C4A and C4B (0.14 for each isotype), i.