Cell-Mediated Immunity
Cell-mediated immunity refers to T-cell protection of your cells. T-cells
protect the inside or intercellular spaces of cells from microorganisms like
viruses and some bacteria. T-cells, like B-cells, have antigen-binding
receptors on their surfaces, and are very adept at recognizing cellular
antigens.
PRIMARY RESPONSE — Antigens activate T-cells, which then begin to
divide and create cytotoxin (cytolytic) T-cells. Cytotoxic T-cells produce
cytokines, or lymphokines, which are proteins (peptides) that stimulate
additional immune response by increasing T-cell formation, macrophage
involvement, etc.
T-cells cannot recognize foreign antigens without the help of macrophage
processing. This helps a T-cell differentiate between types of antigens. Helper
T-cells (called T4s) secrete interleukin, which stimulates B-cell activity and
other T-lymphocytes.
Macrophage ProcessingPHASE ONE
Macrophages ingest antigens by endocytosis and break them down into
several small pieces.
Each piece is “stamped” with a protein (major histo-compatibility [MHC]
proteins).
Now these pieces of antigens are ready to bond with helper T-cells.
B-cell phagocytosis is similar to macrophage phagocytosis.PHASE TWO
Macrophage and B-cells process antigens.
Macrophages secrete interleukin-1.
Interleukin stimulates helper T-cells to produce interleukin-2.
Interleukin stimulates helper T-cells to divide.
Helper T-cells stimulate B-cells.White Blood CellsNeutrophils