Haematologia 17. (1984)
1984 / 1. szám - Dierich, M. P. - Schulz, T.: Physiological and pathological effects of activated complement
4 M. P. Dierich, Th. Schuh: Effects of activated complement Table 1 Physico-chemical characteristics of factors of the complement system also by a direct interaction of certain membrane proteins of murine leukaemia viruses with Clq and Cls in the absence of antibody [5, 6]. The resulting C5b is the nucleus for the formation of the C5b-9 complex. APCA is activated by bacteria, their lipopolysaccharides, dextransulfate and appropriate surfaces [7-9]. From C3 and factor B the complex C3b, B is derived. The mechanism which leads to the ‘first’ C3b in the ‘first’ C3b, B complex could not be explained until recently; the explanation will be discussed below. B is cleaved into Bb and Ba by factor D in a reaction depending on Mg+ + . C3b, Bb, the alternative pathway C3 convertase is capable of splitting C3 into C3a and C3b, the latter being deposited on the activating surface close to the C3b, Bb complex. This gives rise to C3b, Bb, C3b formations which cleave C5 and thus trigger the terminal complement sequence. Like C2a in the convertase of CPCA. Bb functions as the enzymatic centre of the convertase built up by APCA. There exist striking biochemical similarities between C2a and Bb [10]. In addition both are coded for by genes of the major histocompatibility complex (MHC) [11, 12]. Apart from the genes for C2 and B only the genes for C4 are located in the MHC, while genes for the other components are found on other chromosomes [11, 12]. Activation of C3 by cleavage into C3a and the large fragment C3b can be brought about not only by C4b, C2a, the classical pathway C3 convertase, or C3b, Bb, the alternative pathway C3 convertase, but also by proteases like elas- MW Chains Serum concentration /ig/ml Electrophorectic mobility pH 8.6 Clq 410 000 18 150 yl Clr 83 0001 50ß Cls 83 0001 50 ßl C4 206 0003 640 ßl C2 117 0001 25 ßl C3 190 0002 1200-1500 ßl C5 180 0002 75 ßl C6 128 0001 64 ßl C7 121 0001 54 ßl C8 154 0003 54y 1 C9 79 0001 58a B 93 0001 240 ßiD 24 0001 2 a P 220 0004 20/ H 150 0001 450ß J 93 0002 35ß Cl INA 105 0001 240 oc S-protein 71 0001 500 17, 1984 Haematologia