These crossreactive
T cells react differently to the heterologous epitopes
than to homologous epitopes by producing high levels of proinflammatory
cytokines, but they lose their cytolytic activity. Delayed
virus clearance would prolong activation of such crossreactive
CD8 T cells, which then results in the production of
high levels of cytokines such as TNF-, IL-6, or other soluble
factors that affect vascular permeability. The phenomenon
where cross-reactive memory T cells for the primary infecting
virus are more efficiently activated, due to the increased frequency
and higher activation state of memory cells, has been
called original antigenic sin (OAS).