Cell desensitization by sublytic C5b-9 complexes and calcium ionophores depends on activation of protein kinase C

Sarah Kraus, Zvi Fishelson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Basal cell resistance to lysis by complement C5b-9 complexes depends on extracellular and intracellular protection. Cell membrane regulatory proteins and enzymes interfere with complement activation and intracellular processes of protein phosphorylation and synthesis support cell resistance and damage repair. K562 human erythroleukemic cells treated with sublytic complement doses become protected from lytic doses of complement within 50 min. The early signaling processes leading to cell desensitization to complement-mediated lysis were studied. Treatment with calcium ionophores or phorbol 12-myristate 13-acetate rapidly induced in K562 cells protection from complement as well as synthesis of a large protein complex similar to the large complement-induced protein complex L-CIP induced by sublytic complement. Both ionophore- and complement-induced protection were blocked by treatment with protein kinase C (PKC) inhibitors. Calphostin C, sphingosine and GF109203X abrogated complement-induced protection almost completely, whereas Go6976 inhibited it only partially. Since Go6976 is a selective inhibitor of the conventional PKC type, it is proposed that sublytic complement doses activate both conventional and non-conventional PKC types. Immunofluorescence analysis of K562 cells demonstrated sublytic complement-induced translocation of the conventional PKCα and PKCβII from the cytoplasm to the plasma membrane. These results indicate that PKC activation is an early obligatory signal in cell desensitization by sublytic C5b-9 or calcium ionophore.

Original languageEnglish
Pages (from-to)1272-1280
Number of pages9
JournalEuropean Journal of Immunology
Issue number5
StatePublished - 2000


  • Calcium ion
  • Complement resistance
  • Desensitization
  • Ionophore
  • Protein kinase C


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