While the subsistence of ‘professional’ antigen presenting cells partially ameliorates the dilemma of the self or non-self discrimination, it remains hard to understand how it is possible that the cell's class II molecules are not deluged with the processed ‘self’ molecules (for illustration, albumin is present at very high quantities in the serum, so one might suppose that peptides from this alone would suffice to compete for any transiently present non-self proteins). Speculate on and/or research potential mechanisms that would afford improved processing or recognition of potentially dangerous molecules versus the most probably not so dangerous self antigens.