Evidence for the involvement of protein-carbohydrate interaction in hematopoietic, multipotential colony-stimulating...

Immunologically important mediators have been shown to exhibit ability to specifically bind distinct carbohydrates. This type of protein-carbohydrate interaction is one mechanism how to explain involvement of glycochemical interactions in regulatory processes. Interference of certain saccharides with murine multipotential colony-stimulating factor (multi-CSF)-dependent colony formation from progenitor cells in semisolid agar raised evidence for similar potential involvement of protein-carbohydrate interactions. Affinity depletion of conditioned WEHI-3B-medium on resins, bearing saccharides that have been elucidated to be effective inhibitors (mannose and lactose), resulted in preparations with significantly reduced capability to sustain development and proliferation. Sequence comparison of multi-CSF to carbohydrate-binding proteins (lectins) with this specificity failed to uncover extended homologies in diagonal plots. But detailed sequence alignments revealed confined, high-scoring stretches of homology between various lectins and two types of CSF. These results prove the importance of protein-carbohydrate interactions in stem cell proliferation.