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NF-κB is important in many biological processes and is activated by ubiquitous protein kinases. However, in T cells, its activation is regulated by a specific set of adapter proteins.
T cell help is not obligatory for B cell Ig class switching. Instead, DC expression of BLyS and APRIL can provide the signals to induce T-independent B cell production of IgG and IgA.
“Cross-presentation” can prime CD8+ T cells. A transplantation system now reveals its role in destruction of the host endothelial cells that feed the graft.
Historical insight: The clonal selection theory of antibody formation has recently been subjected to challenge from many quarters. A review of its history and that of scientific theories in general points to the importance of distinguishing between the central hypotheses of a theory and its subsidiary implications.
FcεRI activation of mast cells was thought to be Lyn-dependent. It now appears that FcεRI also uses a Fyn kinase–dependent pathway that is essential for mast cell degranulation.