After initial T-cell–DC contacts, T cells migrate again and sample several other DCs. However, T-cell migration is diminished appreciably in the presence of an antigen with high affinity for a given TCR that elicits a relatively strong Ca2+ signal in T cells. The continued use of intracellular dyes that change their fluorescence properties upon binding to Ca2+ will advance our investigation of this crucial role of Ca2+ signalling in T-cell migration and antigen recognition. Hence, 2P microscopy coupled with the quantification of intracellular Ca2+ signalling by T cells activated by different antigens in vivo can be informative buy MG-132 about the relative strength of T-cell–DC interactions
and the immune responses that follow under conditions of health and disease. The relative strength of TCR signalling in vivo can also be measured
by following the shedding of CD62L from the surface of T cells.[93] A few minutes after TCR activation in a T cell, the CD62L extracellular domain is cleaved by the protease ADAM17 (a disintegrin and metalloproteinase domain-containing protein 17). The extent of CD62L shedding reflects TCR signal strength, i.e. a strong TCR signal elicits increased shedding of CD62L. Hence, T-cell dynamics in vivo may be tracked together with TCR signals by measuring the disappearance of CD62L after in vivo staining with fluorescent anti-CD62 antibody Fab fragments. The functional role of NKT cells has been analysed in mice selleck products using CD1d−/− (lack both type I and type II NKT cells) and Jα18−/− (lack only type I NKT cells) mice as well as using blocking or depleting antibodies reactive to CD1d and the semi-invariant TCR. The combined use of both of these mouse strains and antibodies has allowed us to ascribe the outcome of specific immune responses to the effect of either type I NKT cells or type Fenbendazole II NKT cells. However, various compensating
mechanisms, such as an altered conventional TCR repertoire, may control NKT cell function in such knockout mouse environments. Our understanding of the roles of NKT cells in the induction and/or protection from autoimmune disease has taken advantage of analyses of NKT cells in such diseases that either arise spontaneously or are antigen-induced (Table 4). It is important to note while αGalCer has been informative about type I NKT cell activation and function, it has not revealed a comprehensive understanding of the physiological role of type I NKT cells. A role for type I NKT cells in the regulation of autoimmune disease was provided by observations that fewer type I NKT cells are found in both spontaneous autoimmune disease models, type 1 diabetes in NOD mice and systemic lupus erythematosus in MRL/lpr mice.[94, 95] However, CD1d deficiency did not result in potentiation of disease, as expected in all models.