Page 1155 - Veterinary Immunology, 10th Edition

induce remission. Similar results may be obtained with
VetBooks.ir lymphokine-activated T killer (T-LAK) cells. T-LAK cells are

generated by taking the patient's peripheral blood lymphocytes,
culturing and activating them in vitro with interleukin-2, and then

returning them intravenously to the patient. This procedure has
been shown to be effective in some dogs (Fig. 35.3).

FIG. 35.3 The production of lymphokine-activated killer (T-LAK)
cells by incubation of blood lymphocytes in the presence of IL-2 for
4 to 7 days.

The products of mutated genes or abnormally expressed cellular

proteins may be processed and presented to T cells. As a result,
lymphocytes from some tumor-bearing animals may kill cancer
cells cultured in vitro. For example, a protein called cyclin B1 that

regulates mitosis is barely expressed in normal cells but
overexpressed in many tumors, where it can stimulate T cell
cytotoxicity.
Checkpoint inhibitors have shown activity against many different
tumor types, and it is believed that their effectiveness is due to

enhanced cytotoxic T cell activity overcoming inhibitory receptor
induced tolerance (Box 35.1). Implicit in this is the fact that these T
cells must recognize some peptides presented by the MHC I of

malignant cells. These antigens may be normal cellular proteins to
which tolerance is weak, or, alternatively, they may be neoantigens
—peptides that are not present in normal animals and created by
tumor specific mutations.

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