Inhibition of B cell-mediated antigen presentation by intravenous immunoglobulins (IVIg).
Previous work from our laboratory revealed that IVIg interacted with intracellular proteins involved in antigen presentation in B cells, suggesting that IVIg might interfere with the process of antigen presentation in these cells. In the present work, we used an in vitro assay with ovalbumin as model antigen and showed that IVIg inhibited both BCR-dependent and BCR-independent antigen presentation. The inhibition could not be explained by a modulation of expression of MHC II molecules expressed on B cells and was shown to occur in an FcgammaRIIb-independent manner, suggesting that the events responsible for the inhibitory effect occur at the intracellular level. This was supported by the observation of a direct correlation between the level of spontaneous internalization of two different proteins (IVIg and HSA) and their inhibitory potential. The inhibition of B cell-mediated antigen presentation reported here may help explain some of the anti-inflammatory effects of IVIg observed in treated patients, such as a decrease in autoantibody production.
Department of Research and Development, Héma-Québec, Québec (Qc), Canada.
Dominic
D
Paquin Proulx
Eric
E
Aubin
Réal
R
Lemieux
Renée
R
Bazin
D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects* / Q000276:immunology; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D002469:Cell Separation; D005260:Female; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis / Q000276:immunology; D016756:Immunoglobulins, Intravenous / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D011947:Receptors, Antigen, B-Cell / Q000187:drug effects / Q000276:immunology / Q000378:metabolism
D000949:Histocompatibility Antigens Class II; D016756:Immunoglobulins, Intravenous; D011947:Receptors, Antigen, B-Cell