Antigen-presenting cells do not discriminate between self and nonself.

The immune response to F protein in mice provides a system in which the capacity of antigen-presenting cells to present autologous protein to T cells can be examined. When we used the F-type 1 (F.1) and F-type 2 (F.2) combination, these cells proved equally able to present autologous and foreign protein in both an in vivo adoptive transfer and an in vitro proliferation assay. This formally excludes the possibility that these cells themselves discriminate between self and nonself, while still allowing the possibility that their uptake of antigen may be regulated by lymphocyte products.