Bakakos P., Cheilas G. The importance of T cells in regulating antibody production is well established and we understand a great deal about the mechanism that allergen-specific T cells interact with allergen specific B cells. T cells have very precise antigen recognition requirements. It is well known that T cells play a major role in the regulation of inflammation in bronchial asthma, possibly through the production of cytokines. It has been demonstrated in animal models, but also in humans that T cell subsets, defined by a different β-chain, show functional differences. In the human context, analysis of TCR family usage at sites of inflammation such as the airways, can yield insight into the forces that drive the formation of TCR repertoire and the pathogenesis of inflammation. These studies provide further encouragement to those who believe in the importance of T cells in the pathogenesis of asthma and create new perspectives in the understanding of the mechanisms that underlie inflammation. Pneumon 2004, 17(2):145-149.