title: Multiple ligand interactions for bacterial immunoglobulin-binding proteins on human and murine cells of the hematopoetic lineage.
abstract: A group of bacterial Ig-binding surface proteins were studied: protein H and M1 are from Streptococcus pyogenes and interact with IgG, protein L is expressed by Peptostreptococcus magnus and shows affinity for Ig light chains, whereas protein LG is a chimeric construction combining the binding properties of protein L with the IgG-binding activity of protein G from group C and G streptococci. Proteins L and H coupled to Sepharose were mitogenic for human peripheral blood lymphocytes (PBL) and mouse splenic B cells, but not when added in soluble form. Differentiation to Ig secretion was induced by protein H-Sepharose in mouse splenic B cells but not in human PBLs. In FACS analysis FITC-labelled protein H stained virtually all CD19+ cells in human peripheral blood as well as a majority of the CD3+ population. Protein L bound the majority of the CD19+ population, but also a fraction of the CD19-/CD3 population. Protein M1 was not mitogenic but stained the entire CD19+ population and 70% of the CD3+ population. Identical staining patterns were observed with mouse splenocytes using B220 and T-cells receptor as lineage markers. The chimeric protein LG was a potent mitogen for mouse splenic B cells when added either coupled to Sepharose or in soluble form. In addition, protein LG induced differentiation to Ig secretion of the responding mouse splenic B cells. In FACS analysis, protein LG stained the entire CD19+ and the majority of the CD19-/CD3 lymphocyte population as well as all B220+ mouse splenocytes and a fraction of the splenic T cells. These data indicate that the bacterial proteins studied interact with surface structures of several leucocyte populations and can hence interfere with the immune system at multiple levels.
authors.affiliation: Immunology Unit, University of Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Axcrona
authors.forename: L
authors.initials: L
authors.lastname: Björck
authors.forename: T
authors.initials: T
authors.lastname: Leanderson
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002454:Cell Differentiation; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism*; D008213:Lymphocyte Activation; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008934:Mitogens; D011993:Recombinant Fusion Proteins; D013154:Spleen / Q000166:cytology; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D007136:Immunoglobulins; D008565:Membrane Proteins; D008934:Mitogens; D011993:Recombinant Fusion Proteins; C064006:protein H, Streptococcus