Novel lectin-like proteins on the surface of human monocytic leukemia cellline THP-1 cells that recognize oxidized cells

Presence of lectin-like receptors on the membranes of human monocytic leuke mia cell line THP-1 cells for clustered sialylated poly-N-acetyllactosaminy l sugar chains on the membranes of oxidized erythrocytes and T-lympoid cell s was investigated. Membranes of THP-1 cells differentiated into macrophage s were solubilized, and the membrane proteins obtained by affinity chromato graphies using lactoferrin-Sepharose and band 3-Sepharose were purified by successive DE column chromatography and sodium dodecyl sulfate-polyacrylami de gel electrophoresis. Proteins of 50, 60, and 80 kDa with specificity to bind to sialylated poly-N-acetyllactosaminyl sugar chains were detected in the chromatographic fractions. A 50-kDa protein was isolated in a pure form . N-Terminal amino acid sequence of the protein was Lys-Gln-Lys-Val-Ala-Gly -Lys-Gln-Pro-Val-, which has not been found in the N-terminal regions of th e hitherto known proteins. The antibody, raised against the chemially synth esized peptide composed of the N-terminal amino acid sequence, bound to 50- , 60-, and 80-kDa proteins as analyzed by immunoblotting and immunoprecipit ation, indicating that these proteins had the same N-terminal amino acid se quence. The results demonstrate that THP-1 cells have novel 50-, 60-, and 8 0-kDa lectin-like proteins with the same N-terminal amino acid sequence on the cell surface which would bind to clustered sialylated poly-N-acetyllact osaminyl sugar chains generated on oxidized erythrocytes and T-lymphoid cel ls, (C) 2001 Academic Press.