Table 3.
Feature | Type of selection | |
T cell selection in the thymus | Sperm receptor selection in the testis | |
Positive selection on MHC molecules | T cells with low affinity for self-MHC survive | Probably not necessary |
Negative selection with self-molecules on/in cells with ‘promiscuous’ transcription | T cells lacking high affinity to self-MHC:peptide complexes survive | Spermatozoa are fitted with receptors that lack self-reactivity |
Consequence | T cells recognize nonself-MHC:peptide complexes | Spermatozoa recognize nonself-ligands |