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J Clin Invest. 2007 Jun;117(6):1558-65. Epub 2007 May 17.

Mature B cells class switched to IgD are autoreactive in healthy individuals.

Author information

1
Molecular Immunogenetics Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.

Abstract

Determination of the origin and fate of autoreactive B cells is critical to understanding and treating autoimmune diseases. We report that, despite being derived from healthy people, antibodies from B cells that have class switched to IgD via genetic recombination (and thus become class switched to C delta [C delta-CS] cells) are highly reactive to self antigens. Over half of the antibodies from C delta-CS B cells bind autoantigens on human epithelioma cell line 2 (HEp-2) cells or antinuclear antigens, and a quarter bind double-stranded DNA; both groups of antibodies are frequently polyreactive. Intriguingly, some C delta-CS B cells have accumulated basic residues in the antibody variable regions that mediate anti-DNA reactivity via somatic hypermutation and selection, while other C delta-CS B cells are naturally autoreactive. Though the total percentage was appreciably less than for C delta-CS cells, a surprising 31% of IgG memory cell antibodies were somewhat autoreactive, and as expected, about 24% of naive cell antibodies were autoreactive. We interpret these findings to indicate either that autoreactive B cells can be induced to class switch to IgD or that autoreactive B cells that use IgD as the B cell receptor are not effectively deleted. Determination of the mechanism by which the majority of C delta-CS B cells are autoreactive may be important in understanding peripheral tolerance mechanisms and may provide insight into the enigmatic function of the IgD antibody.

PMID:
17510706
PMCID:
PMC1866247
DOI:
10.1172/JCI27628
[Indexed for MEDLINE]
Free PMC Article

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