DEPRESSED IMMUNE SURVEILLANCE AGAINST CANCER - ROLE OF DEFICIENT T-CELL - EXTRACELLULAR-MATRIX INTERACTIONS

Although T cells infiltrate malignant tumors, the local immune respons e is usually inefficient and tumors escape destruction. While extracel lular matrix proteins strongly costimulate T cell responses in normal individuals, our studies indicate that peripheral blood T cells from c ancer patients and tumor infiltrating cells respond poorly or are resi stant to stimulative signals mediated by collagen I and IV and fibrone ctin. Moreover, the adhesive properties of cancer T cells are markedly depressed. Those functional deficiencies are paralleled by variable d eficits in integrin and non-integrin T cell receptors for extracellula r matrix. Immunotherapy with BCG causes a dramatic but transient incre ase in T cell : ECM interactions.