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A chemotactic protein for polymorphonuclear leukocytes (lung carcinoma-derived chemotaxin [LUCT]) was purified from culture fluid of the human lung giant cell carcinoma LU65C cells to electrophoretically homogeneous form through five sequential purification steps: DEAE-Sepharose, CM-Sepharose, HPLC on carboxyl-methylated-polyvinylalcohol resin, hydrophobic, and reversed-phase. The molecular mass was determined as approximately 10 kD by SDS-PAGE and isoelectric point was 10.7. The chemotactic activity (ED50 0.75 x 10(-9) M) was sevenfold more potent than that of FMLP (5 X 10(-9) M) and comparable with that of C5a (10(-9) M). NH2-terminal amino acid sequence and amino acid composition of LUCT strongly suggest that it may be closely related to the putative protein encoded by the cDNA clone (3-10C) and almost identical with a part of sequence of the chemotactic factor derived from stimulated human leukocytes in the 6th to 32nd, but not the NH2-terminal 5 amino acids. These results indicate that the carcinoma cells produce LUCT without any added stimulant and suggest that the previously isolated chemotactic monokines may correspond to des(1-5) of LUCT in the NH2-terminal region.

We herein describe CD9 (p24) antigen as existing on the cell surface of megakaryocyte lineage leukemias as well as megakaryocytic leukemia cell line, MEG-01 and HEL, by means of fluorescence-activated cell sorter (FACS IV) with a panel of monoclonal antibodies (Mabs). We found CD9 antigen expression on the cell surface of megakaryoblastic leukemias as well as MEG-01 and HEL cells. Furthermore, CD9 antigen expression increased while culturing these cells with phorbol esters, and was also found in the cytoplasm by means of indirect immunofluorescence test. These findings clearly showed that CD9 antigen exists on the cell surface of megakaryocytic cells which are capable of synthesizing the CD9.

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