Tumor Immunology

Understanding of the mechanisms involved in the induction of immunity and the recognition of antigens by effector cells has improved dramatically in the past decade as molecular biology has joined forces with classic tumor immunology. This improved molecular understanding has led to many new therapeutic approaches. For example, immune responses can be dramatically altered by single amino acid changes in either antigens or receptors.

A tumor-associated antigen (TAA) is an antigen that is relatively restricted to tumor cells. Tumor-specific antigens (TSAs) are antigens unique to tumor cells. The development of tumors despite the presence of antigens, the significance of immune recognition in the pathogenesis of tumors, and the potential for therapeutic augmentation of immune responses are the subjects of intense investigation.

Tumor Anitigens

Antigens present on tumor cells but not present or apparent on normal cells.

In animal experiments, most tumors induced or transplanted into syngeneic recipients provide immunity against subsequent challenge with the same tumor but not against challenge with transplanted normal tissues or other tumors. Tumor antigens are particularly well demonstrated by (1) chemical carcinogen-induced tumors, which tend to have specific antigens that vary among tumors, even among tumors induced by the same carcinogen, and by (2) virus-induced tumors, which tend to show cross-reactivity between tumors induced by the same virus. Viral infections may result in "modified self," ie, new antigens recognized in the context of the major histocompatibility complex (MHC).