Page 37 - Veterinary Immunology, 10th Edition
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FIG. 1.5 A simple flow diagram showing the essential features of
the humoral and cell-mediated adaptive immune responses.
Because antibodies do not work inside cells, immunity to
intracellular invaders is the function of T cells. The T cells can
destroy infected or abnormal cells. This type of response is
therefore called the “cell-mediated immune response.” There are
three major types of T cell. One is responsible for killing abnormal
cells and so consists of cytotoxic T cells. Another type is responsible
for providing the signals that activate the adaptive immune
responses and hence are called helper T cells. The third cell type
regulates immune responses and so are called regulatory T cells.
Most importantly, adaptive immune responses generate long-lived
populations of memory T and B cells that ensure that this immunity
persists for a long time, perhaps even as long as the animal's
lifetime.
Antibody-Mediated Immunity
Soon after it was discovered that animals could be made immune to
infectious agents by vaccination, (Chapter 24) it was recognized
that the substances that provided this immunity could be found in
blood serum. For example, if blood is taken from an immune horse
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