Research Notes.

The article presents research notes on issues dealing with nature immunology. Although most primary effector T cells die during the contraction phase, small numbers survive to become memory cells. A study links expression of homodimeric CD8 α chains to CD8 memory cell generation. Terminally differentiated B cells secrete antibodies, but additional factors influence whether these cells undergo further immunoglobulin gene diversification, such as somatic hypermutation and class-switch recombination.