Figure 5.

The left hand upper panel shows a co-selection mechanism for induction of transplantation tolerance in vertebrate C based on the interactions of Figure 2. Anti-B antibodies stimulate anti-anti-BT cells and the anti-anti-B antibodies stimulate anti-B T cells. There is co-selection of the anti-anti-B T cells and the anti-B T cells, taking the immune system of C to a state in which there are elevated levels of these two T cell populations. This is a state of the vertebrate C that is specifically suppressed with respect to making an immune response to B.The lower panel shows a polyclonal version of this vaccination. Immunization of strain A with strain B tissue causes production of anti-B plus anti‑anti-A IgG, while the converse immunization produces anti-A plus anti-anti-B IgG. The anti-A antibodies in the latter IgG are removed by absorption with A tissue (lymphocytes) yielding anti‑anti-B IgG without anti-A antibodies. A vertebrate of phenotype C receives infusions of anti-anti-B plus anti-B IgG. C also receives anti-anti-A IgG, but in the absence of anti-A IgG there is no A-specific positive feedback loop.The right hand panels show the anti-BL/6 CTL response following treatment of 20C3H mice with weekly infusions of 1μg anti-BL/6 IgG plus 1μg anti-anti-BL/6 IgG, given either IV or IP. Sequential panels show the CTL responses after 2, 3, 4, 5 or 6 infusions respectively. CTL were measured in individual spleen samples after stimulation with BL/6 or third-party control (BALB/c) cells. Data show % lysis (20:1 effector target) in groups of 4 mice. * P<.05, MANOVA.