A change in the morphology or behavior of a cell resulting from exposure to an activating factor such as a cellular or soluble ligand, leading to the initiation or perpetuation of an immune response.

The process in which a pro-T cell becomes committed to becoming a gamma-delta T cell.

The process in which a lymphoid progenitor cell becomes committed to becoming any type of T cell.

The process in which a pro-T cell becomes committed to becoming an NK T cell.

The process in which a pro-T cell becomes committed to becoming an alpha-beta T cell.

The process in which a CD4-positive, alpha-beta T cell becomes committed to becoming a CD4-positive, CD25-positive, alpha-beta regulatory T cell.

The process in which an immature T cell becomes committed to becoming a CD4-positive, alpha-beta T cell.

The process in which a precursor cell type acquires the specialized features of a CD4-positive, CD25-positive, alpha-beta regulatory T cell.

The process in which a relatively unspecialized T cell acquires specialized features of a mature CD4-positive, alpha-beta T cell.

The expansion of a B-1 B cell by cell division. Follows B cell activation.

The non-specific expansion of B cell populations within a whole or part of an organism to reach to a total number of B cells which will then remain stable over time in the absence of an external stimulus.

Reactions triggered in response to the presence of a tumor cell that act to protect the cell or organism.

Any process leading to negative selection of B cells in the periphery.

Any B cell selection process that occurs in the periphery.

Any process leading to negative selection in B cells. Mechanisms of negative selection include anergy and deletion.

The series of events in which a stimulus from a tumor cell is received and converted into a molecular signal.

Any process leading to negative selection of B cells in the bone marrow.

Any B cell selection process that occurs in the bone marrow.

A series of reactions that takes place outside the cell occurring in response to tissue damage and initiated within blood plasma by the action of activated Factor XII (Hageman Factor) on prekallikrein to convert it to plasma kallikrein, and the subsequent reaction of plasma kallikrein with high molecular weight kininogen. The ultimate product of the plasma kallikrein-kinin cascade is bradykinin, an agent known to induce smooth muscle contraction, vasoconstriction, and increased vascular permeability.

A series of reactions that takes place outside the cell that occur as a result of by-products of tissue damage, including collagen, cartilage, and basement membrane. The ultimate product of the kinin cascade include kallidin and bradykinin, agents known to induce smooth muscle contraction, vasoconstriction, and increased vascular permeability.