I recently stumbled upon this review and thought it would be interesting to share as it challenges mainstream immunological knowledge of the difference between innate and adaptive immunity. Although I’ve never seen any text that explicitly differentiates adaptive immunity as the only branch that provides immunological memory via the production of antibodies and innate immunity as a “knee-jerk” cell-based response, that’s kind of what I have been assuming. However, this review introduces a fairly recently discovered set of B and T cells that produce autoreactive antibodies in an innate immunity sort of way.
The authors point out that conventional knowledge dictates that the innate immunity comprises of germ-line coded receptors while the hallmark of adaptive immunity involves random recombination of V,D and J gene segments followed by clonal selection and expansion of select antigen-specific B and T cells to generate memory. However, a subset of B and T lymphocytes do not play by these rules. Instead of being clonally aborted for auto-reactivity, their defining feature is to be autoreactive. These lymphocytes (B-1 B cells, marginal zone B cells, γδ T cells and CD1d-restricted natural killer T cells) express germ-line encoded BCRs and TCRs with limited diversity. They recognize conserved structures of self-origin (instead of variable foreign antigens) and have a “natural memory.”
Some questions the authors bring up that are interesting to think about:
- Why are these autoreactive cells useful and not harmful to the host?
- How do they escape negative selection?
Reference:
Bendelac A, Bonneville M and Kearney JF. “Autoreactivity by design: Innate B and T lymphocytes.” Nature Reviews 1(2001): 177-186.
Thanks for the post! Interesting subset of the cells. It looks like the cells are specific to "conserved stress-induced self-structures". As if the cells under stress would produce and present proteins that would activate this subset of cells and have stressed cells eliminated.
ReplyDeleteThis subset of cells may escape negative selection perhaps only because these stress induced structures are not presented to B and T cells during development.
Are there autoimmune disorders linked to these subset of lymphocytes?
I read something about this in an article posted in Science a few months back and became intrigued, as well. One of the theories was that these cells do not become reactive until they reach their target tissue and survive deletion. One recent paper seems to support this possibility (Pubmed 22065673.)
ReplyDeleteHello,
ReplyDeleteThis is the perfect blog for anyone who wants to know about this topic. Adaptive immune system is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic growth, which are carried out by different lymphocyte cells...