Immunodeficiency And Cancer

Many factors in our immune systems have anti-tumor effects…

--Cytotoxic T-cells (CD8+) have been shown to provide a specific sensitivity

toward some tumors, especially virus-associated tumors (ie. EBV-induced Burkitt lymphoma and HPV-induced tumors). They recognized peptide antigens that are on the cell surface latched into an MHC protein (MHC 1).

--Natural Killer (NK) cells are able to destroy tumor cells without prior

sensitization and they are possibly our first line of defense against tumors. Work complementary to T-cells, but CD8+ T-cells cannot recognize tumors unless they show MHC 1 proteins, however, the NK cells can.

--Macrophages show selective cytotoxicity to tumor cells, and are activated by T-

cells and NK cells (through their secretion of INF-gamma). They kill cells by the same way they kill normal microbes (secretion of oxygen metabolites) or they can secrete tumor necrosis factor (lyses many tumor cells).

--Humoral mechanisms function in two ways: (1) activation of complement, and (2) induction of Ab-dependent cellular toxicity by NK cells

Category: Pathology Notes