The novel IgD binding protein from Moraxella catarrhalis induces human B lymphocyte activation and Ig secretion in the presence of Th2 cytokines.
Moraxella IgD binding protein (MID) is a novel bacterial outer membrane protein with IgD-binding properties. MID was purified from the respiratory pathogen Moraxella catarrhalis and is here shown to have B cell stimulatory properties. Purified MID in the range of 0.01-0.1 microg/ml was optimal to induce a proliferative response in human PBL. MID coupled to Sepharose and formalin-fixed M. catarrhalis preparations induced similar proliferative responses in PBL cultures. MID or MID-Sepharose stimulated purified human peripheral B cells as measured by proliferation. In contrast, MID or MID-Sepharose did not activate T cells. Preincubation of purified B cells with anti-IgD Abs inhibited MID-Sepharose-induced B cell proliferation. The addition of IL-4 specifically induced IL-6 production in MID-Sepharose-activated B cells. IgM secretion was detected in B cell cultures stimulated with MID or MID-Sepharose and IL-2 for 10 days. Secretion of IgG and IgA was efficiently induced in cultures from purified B cells stimulated with the combination of MID or MID-Sepharose and IL-4, IL-10, and soluble CD40 ligand, suggesting that Th2-derived cytokines were required for optimal plasma cell generation. Taken together, MID has properties that make it an important tool to study IgD-targeted activation of B cells.
Gjörloff Wingren
Anette
A
Department of Medical Microbiology, University Hospital Malmö, Lund University, Malmö, Sweden.
Hadzic
Radinka
R
Forsgren
Arne
A
Riesbeck
Kristian
K
D018829:Adhesins, Bacterial; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002352:Carrier Proteins / Q000494:pharmacology*; D016207:Cytokines; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis; D007072:Immunoglobulin D / Q000502:physiology; D007074:Immunoglobulin G / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000187:drug effects*; D018418:Th2 Cells / Q000276:immunology*
D018829:Adhesins, Bacterial; D002352:Carrier Proteins; D016207:Cytokines; C439616:IgD-binding protein MID, Moraxella catarrhalis; D007070:Immunoglobulin A; D007072:Immunoglobulin D; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007376:Interleukin-2; D015850:Interleukin-6