title: A C9 related channel forming protein in the cytoplasmic granules of human large granular lymphocytes.
abstract: Large granular lymphocytes (LGL) from human blood maintained in culture for 2 to 6 weeks with IL-2 were found positive in the K562 cell killing assay. The cytoplasmic granules of the LGL were isolated, lysed and the soluble proteins were passed over a Sepharose-anti-C9 column. The retained protein was eluted with NaCl and found to consist by SDS polyacrylamide gel electrophoresis of essentially one component with a molecular weight of approximately 70 000. The protein did not give a positive precipitation test with anti-human C9 by Ouchterlony analysis, but it reacted reproducibly with anti-human C9 by Western blot analysis. By ELISA the cross reaction with human C9 was less than 1%. The C9 related lymphocyte protein lacked C9 hemolytic activity, but it formed functional pores in liposomes in presence of Ca++. These results suggest that the cytoplasmic granules of human LGL that are capable of killing NK target cells contain C9 related protein which is involved in the cellular cytotoxicity reaction.
mesh_terms: D002478:Cells, Cultured; D003186:Complement C9 / Q000378:metabolism*; D015938:Complement Membrane Attack Complex; D003165:Complement System Proteins; D003594:Cytoplasmic Granules / Q000032:analysis*; D006801:Humans; D007694:Killer Cells, Natural / Q000032:analysis*; D008081:Liposomes / Q000032:analysis; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000032:analysis / Q000302:isolation & purification*; D008970:Molecular Weight; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012542:Scattering, Radiation; D013329:Structure-Activity Relationship
chemical_list: D003186:Complement C9; D015938:Complement Membrane Attack Complex; D008081:Liposomes; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D003165:Complement System Proteins