Table 1. Some factors that influence the strength of T cell responses.

T cell-related factors	Interactions between T cells and antigen presenting cells
	• Affinity of the T cell receptor-peptide-MHC interaction
	• Co-receptor binding
	• Co-stimulatory and checkpoint molecule interactions
	• Adhesion molecule interactions
	• T cell receptor expression
	Repertoire and precursor frequency of reactive T cells as a result of positive and negative selection
	T cell receptor down-regulation, internalization, or degradation
	Intrinsic T cell signaling/kinase and phosphatase activity
	Activation-induced cell death of the T cell
	Primary vs. memory response
Antigen-related factors	Structure/landscape/available contact points for the T cell receptor
	Presentation of peptide by MHC molecules/peptide-MHC affinity
	Processing of peptides/immunodominance
	Binding register of the peptide within the MHC molecule
	Dose/concentration/density of peptide
Extrinsic factors	Adjuvant used during T cell priming
	Regulatory T cells and other peripheral tolerance mechanisms
	Cytokine milieu
	Nutrient and metabolite availability