Phenotype-associated lectin-binding profiles of normal and transformed blood cells: a comparative analysis of mannose- and galactose-binding lectins from plants and human serum/placenta.

Surface glycoconjugates of normal and transformed blood cells are commonly characterized by plant lectins. To infer physiological significance of protein-carbohydrate interactions, mammalian lectins are obviously preferable as research tools. So far, human serum lectins have not been used to assess their binding to immunophenotyped human normal or transformed blood cells. Thus, our study combines two groups of lectins with different specificity from plant and human sources. Besides concanavalin A (ConA) we have isolated the mannose-binding protein and serum amyloid P component from human serum. Especially the mannose-binding protein is believed to play a role in host defence against bacteria and yeast cells with unknown impact on normal and tumor cells. These three lectins establish the first group. In addition to the immunomodulatory mistletoe lectin, whose binding can elicit enhanced cytokine secretion from mononuclear blood cells, we included the beta-galactoside-binding lectin (14 kDa) from human placenta in the second group. The initial series of measurements was undertaken using two-color flow cytometry to determine the phenotype-associated binding (based on cluster designation; CD) of the lectins to blood and bone marrow cells from normal donors and the cell line CEM (T-lymphoblastoid), KG1-A (primitive myeloid leukemia) and Croco II (B-lymphoblastoid). Heterogeneity was apparent for each lectin in the CD-defined cell populations. Significant differences in binding were noted between Viscum album agglutinin (VAA) and other lectins for CD4+ cells from blood and between mannose-binding protein (MBP) and VAA versus 14 kDa, ConA and serum amyloid P component (SAP) for CD19+ cells from bone marrow.(ABSTRACT TRUNCATED AT 250 WORDS)