“Altered-self” or “near-self” in the positive selection of lymphocyte repertoires?

Positive selection of lymphocyte repertoires is now recognized as applying to both B and T cells. However, much of the early literature on positive selection focussed on cell-mediated immunity (T cells), which biased consideration of its general biological role. The term “altered-self,” which initially captured the idea of self (i.e. MHC) altered by the addition of what was later found to be a peptide fragment, has not proven robust and may now be clouding our understanding. It is recommended that the term “near-self” be reintroduced since it captures the essence of the probable underlying adaptive process-sub-threshold self-reactivity to countermand rapid pathogen mutation.