TY - JOUR
T1 - Complement membrane attack complexes induce in human leukemic cells rapid expression of large proteins (L-CIP)
AU - Reiter, Yoram
AU - Fishelson, Zvi
N1 - Funding Information:
Protection against pathogenic organisms is mediated in part by the twenty plasma proteins which comprise the complement system (Miiller-Eberhard, 1988). The lytic activity is executed by the membrane attack complex (MAC) which is composed of the C5b, C6, C7, C8 and C9 proteins (Miiller-Eberhard, 1988). Upon binding to the C5b-8 complex, the C9 molecules polymerize to form in target cell membranes the typical cylinder-like complement channel observed under the electron microscope (Miller-Eberhard, 1988; Tranum-Jensen et al., 1978; Tschopp et al., 1982). Analysis of the action of complement on mammalian cells indicated that one functional MAC channel is sufficient to cause lysis of an erythrocyte (Mayer, 1961). However, multiple channels are required *This work was supported in part by a grant from the Israel Cancer Association and by a Research Development Award from the Israel Cancer Research Fund. tIncumbent of a Bareeha Foundation Career Development Chair established by the Bareeha Foundation, Geneva. To whom correspondence should be addressed.
PY - 1992/6
Y1 - 1992/6
N2 - The effect of sublytic doses of the complement membrane attack complexes (MAC)1 on protein synthesis in human leukemic cells was examined. As shown herein, rapid protein synthesis is evident in K562 erythroleukemic cells upon exposure to sublytic complement doses. Analysis of cell extracts by SDS-PAGE revealed high molecular weight proteins which appeared in the cells already after 15 min treatment with complement at 37°C, reaching a maximal level after 40-50 min. These large complement-induced proteins (L-CIP) were clearly observed in gels stained by Coomassie blue and in autoradiograms following [35S]-Met or [3H]-Leu incorporation. Rabbit antibodies prepared against L-CIP were reactive in immunoassays with extracts of MAC-treated cells but not of non treated cells. They also bound to the surface of intact K562 cells (as determined by immunofluorescence), but only after treatment of the cells with complement. Both heterologous (rabbit and guinea pig) and homologous (human) sera induced L-CIP synthesis. The induction of L-CIP was indeed mediated by the complement MAC since L-CIP could not be detected in K562 cells exposed to heat-inactivated human serum or C6-deficient rabbit serum. Similarly, C7- or C8-deficient human sera could not induce L-CIP production unless they were reconstituted with purified human C7 or C8, respectively. The synthesis of L-CIP was largely inhibited by the protein synthesis inhibitors cycloheximide and puromycin and partially inhibited by the RNA synthesis inhibitor actinomycin D. L-CIP was similarly induced in two other human leukemic cell lines, U937 and HL-60, but not in K562/S, a subline of K562 which is highly sensitive to complement damage. These results are discussed with respect to the resistance of leukemic cells, and nucleated cells in general, to complement-mediated immune damage.
AB - The effect of sublytic doses of the complement membrane attack complexes (MAC)1 on protein synthesis in human leukemic cells was examined. As shown herein, rapid protein synthesis is evident in K562 erythroleukemic cells upon exposure to sublytic complement doses. Analysis of cell extracts by SDS-PAGE revealed high molecular weight proteins which appeared in the cells already after 15 min treatment with complement at 37°C, reaching a maximal level after 40-50 min. These large complement-induced proteins (L-CIP) were clearly observed in gels stained by Coomassie blue and in autoradiograms following [35S]-Met or [3H]-Leu incorporation. Rabbit antibodies prepared against L-CIP were reactive in immunoassays with extracts of MAC-treated cells but not of non treated cells. They also bound to the surface of intact K562 cells (as determined by immunofluorescence), but only after treatment of the cells with complement. Both heterologous (rabbit and guinea pig) and homologous (human) sera induced L-CIP synthesis. The induction of L-CIP was indeed mediated by the complement MAC since L-CIP could not be detected in K562 cells exposed to heat-inactivated human serum or C6-deficient rabbit serum. Similarly, C7- or C8-deficient human sera could not induce L-CIP production unless they were reconstituted with purified human C7 or C8, respectively. The synthesis of L-CIP was largely inhibited by the protein synthesis inhibitors cycloheximide and puromycin and partially inhibited by the RNA synthesis inhibitor actinomycin D. L-CIP was similarly induced in two other human leukemic cell lines, U937 and HL-60, but not in K562/S, a subline of K562 which is highly sensitive to complement damage. These results are discussed with respect to the resistance of leukemic cells, and nucleated cells in general, to complement-mediated immune damage.
UR - http://www.scopus.com/inward/record.url?scp=0026661321&partnerID=8YFLogxK
U2 - 10.1016/0161-5890(92)90187-3
DO - 10.1016/0161-5890(92)90187-3
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AN - SCOPUS:0026661321
SN - 0161-5890
VL - 29
SP - 771
EP - 781
JO - Molecular Immunology
JF - Molecular Immunology
IS - 6
ER -
