T-CELL ACTIVATION .4. EVIDENCE FOR A FUNCTIONAL LINKAGE BETWEEN MHC CLASS-I, INTERLEUKIN-2 RECEPTOR, AND INTERLEUKIN-4 RECEPTOR MOLECULES

The aim of the present work was to study regulatory interactions between MHC class I molecules and the interleukin (IL)-2, IL-3, and IL-4 receptors and functional interactions between the receptors for IL-2 and IL-4. Our major observations were: (1) quiescent splenic T cells exposed to specific anti-MHC class I antibodies become responsive to IL-2 and IL-4 stimulation; (2) T-cell clones (CTLL-2 and HT-1) grown at high cell density or low IL-2 concentrations become refractory to IL-2 and IL-4 stimulation. After exposure to anti-class I antibodies the refractory cells recover responsiveness to lymphokine-induced proliferation; (3) IL-2 receptor expression is non-inducible in class I-negative T-lymphoma cells, but is inducible following class I gene transfection of the cells; (4) exposure of T-cells and clones to IL-2 receptor antibody increases the responsiveness to IL-4 stimulation; (5) IL-2 and IL-4 act synergistically at low and substimulatory lymphokine levels; and (6) IL-3 responsiveness of hemopoietic cells is not influenced by exposure to anti-MHC class I antibody. It is concluded that class I molecules are of importance for the functional expression of the receptors for IL-2 and IL-4 and that these receptors are functionally interrelated. © 1991.