New roles for TIM family members in immune regulation.

Members of the TIM (T-cell immunoglobulin domain and mucin domain) protein family are emerging as important regulators of immune responses. As their names imply, the TIM proteins were originally thought to be T-cell-specific molecules that served mainly to regulate T-helper-cell responses. However, the recent discovery that antigen-presenting cells also express TIM molecules and the identification of new TIM-protein ligands has expanded the known roles of the TIM proteins in immune regulation.