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What is cell-mediated immune response effective against?

Virus infected cells, tumor cells, grafted tissues, fungi, intracellular parasites, and some intracellular bacteria (e.g. tuberculosis).

What types of T cells are involved in cell-mediated immune responses?

CD4+ (TH1, TH2, etc.) and CD8 (Tc1 and Tc2) T cells.

What distinguishes naïve T cells from effector T cells?

Effector T cells are easier to activate, have increased adhesion molecules, and produce soluble and membrane-bound effector molecules.

What is the role of CD45 in T cell activation?

CD45 is required for the functional coupling of the TCR and its protein tyrosine kinases, playing a crucial role in early T cell activation steps.

How do activated helper T cells stimulate B cells?

Through secretion of interleukin 2 (IL-2), IL-4, IL-5, and IL-6.

What distinguishes CD45RA from CD45RO?

CD45RA is found on naïve T cells, while CD45RO is associated with activated T cells and enhances their signaling.

What mechanisms do cytotoxic T cells use to kill infected or tumor cells?

Cytotoxic T cells use perforin/granzyme pathways and Fas/FasL pathways to induce apoptosis in target cells.

What is the function of Natural Killer (NK) cells?

NK cells recognize and kill infected and tumor cells by their absence of MHC class I and help regulate innate/adaptive immunity.

How do T cells recognize antigen presenting cells (APCs)?

T cells form an immunological synapse with APCs when they encounter cognate antigen presented on MHC molecules.

What happens during the activation of naïve cytotoxic T cells?

They require three signals: recognition of antigen in an MHCI-peptide, a costimulatory signal (CD28-B7), and IL-2 interacting with its receptor.