Antigen-presenting cells control T cell proliferation by regulating amino acid availability

Abstract

All cells depend on nutrients acquired from the extracellular environment to support the biochemical processes required for cell growth. Although unicellular organisms such as bacteria and yeast have developed strategies to survive nutrient limitation, the growth of these organisms is constrained by nutrient availability. In contrast, mammalian cells exist in a nutrient-rich environment where cell growth is not limited by substrate availability, but rather by the levels of extrinsic growth factors (1, 2). Because of the limits imposed by growth factor control, cellular proliferation is restricted even under nutrient conditions that are highly favorable for unlimited cell growth. However, it is becoming apparent that nutrient availability also plays an important role in controlling mammalian cell growth. An example of this form of growth control is found in the work of Angelini et al. (3) reported in this issue that describes how dendritic cells control the proliferation of T cells by regulating the availability of the amino acid cysteine.