There is a lot of literature that supports the role of gut bacteria inducing Tregs, and now there is also some evidence of epitope transport from the gut into the thymus.
Hence, I think these events might matter even if they are not very frequent.
But you could be right, and perhaps there's not really a relevant mutualistic relationship between host and commensals in terms of epitope crossreactivity.
There is a lot of literature that supports the role of gut bacteria inducing Tregs, and now there is also some evidence of epitope transport from the gut into the thymus.
Hence, I think these events might matter even if they are not very frequent.
But you could be right, and perhaps there's not really a relevant mutualistic relationship between host and commensals in terms of epitope crossreactivity.