This is the main response of the T cells to virus infected cells. It is a slow response,e.g. 7 days, even with the presence of memory cells. It is a major cause of viral pathogenesis because of bystander cell damage, even allowing for clonal restriction. MHC11 are present on certain immune cells such as macrophages, B cells, monocytes. Cytokines are small proteins which bind to receptors on other immune cells and modulate their activity.
Cytokines are effective over a short range.
So CD4 cells can bind to immune cells carrying viral antigens if their T cell receptor recognises it. This results in the proliferation of the antigen presenting cells. Natural killer or NK cells. These cells pre-exist, they are not clonally restricted so are not specific. Alpha interferon, released in response to a viral infection causes their proliferation.