Dictionary

Chapter 8

Affinity model of selection - a thymocyte development model that proposes that the affinity of the TCR and MHC-peptide ligands of a thymocyte in the thymus determines whether it is positively or negatively selected. (G-1)

The concept of affinity model of selection in thymocytes is somewhat opposite of how we might think of our relationships with others in that we positively select those who gravitate towards us because of our commonalities.

Lineage commitment- the point at which a multipotent cell selects a particular cell type. For thymocytes it is deciding on being either a CD4+ cell or CD8+ cell. For pluripotent stem cells during hematopoiesis it is whether to be myeloid or lymphoid. from this further distinctions can be made (G-12)

While life is generally not defined by as rigid of commitments such as lineage commitment, there are points at which we must make decisions that can impact the trajectory of our for the foreseeable future.

Self-tolerance - the state in which self-antigens don't elicit a response (G-17)

T-cells exhibit self-tolerance to self-MHC/self-peptides despite the need to identify and have an attraction to self-MHC. (p.301)