Friday, December 16, 2005

Implications of Dedritic Cell Antigen Presentation to B cells

When it comes to Nature magazine, I enjoy it. When my brother got me a subscription I really started to appreciate it. One of the best sections in it is the "Research Highlights", which points out papers that the editors thought where significant but appeared in other journals.

I get the Nature table of contents by email every week, and while I don't always find an interesting article, I always read the research highlights, and that's where this paper came up.
[blockqoute]Cell surface recycling of internalized antigen permits dendritic cell priming of B cells.

Bergtold A, Desai DD, Gavhane A, Clynes R.

Integrated Program in Cellular, Molecular, and Biophysical Studies, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.

Dendritic cells process internalized antigens to present degradative products on MHC for TCR recognition. Because antigen-exposed DCs also induce humoral immunity, DCs must also retain antigen in its native state for the engagement of BCR on B cells. Here, we demonstrate that antigen endocytosed by the inhibitory Fc receptor, FcgammaRIIB, accesses a non-degradative intracellular vesicular compartment that recycles to the cell surface, enabling interaction of native antigen with BCR on B cells. Immunization with IgG-opsonized, T independent antigens leads to enhanced humoral responses in a FcgammaRIIB and complement dependent manner. IC-loaded DCs trafficking to the splenic marginal zone can prime a T independent response in an FcgammaRIIB-dependent manner. Thus dendritic cells are equipped with both non-degradative and degradative antigen uptake pathways to facilitate antigen presentation to both B and T cells.[/blockqoute]

Why is this important? Previously it was thought that B cells had to be exposed to free, native antigen. This changes the picture, showing that dendritic cells can stimulate both T cells and B cells to activate a robust antibody response. Very cool, and it even has some implications on immunotoxicology (agents that selectively affect dendritic cells may cause significant interference in an antibody response). It remains to be seen how important or widely occuring this phenomenon is, but I think it's pretty cool.

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