In vitro initiated secondary anti-hapten response-III separable roles of hapten and carrier in immune paralysis

Mouse spleen cells sensitized to trinitrophenyl hemocyanin (TNP-KLH) undergo an anti-hapten secondary response when challenged in vitro with antigen. High doses of TNP-KLH induced immune paralysis. KLH alone or TNP on a heterologous carrier caused partial paralysis. If both carrier and hapten components were present but separate, paralysis was increased. IgM and IgG anti-TNP responses were affected equally by carrier paralysis and y anti-θ inactivation of T cells suggesting KLH helper cells are thymus derived. Conversely, hapten had a greater effect on IgG cells as would be expected if it acted directly on antibody-producing cells, selecting among them on the basis of avidity. Reconstitution of the anti-TNP response was observed when KLH paralyzed cells were mixed with TNP paralyzed cells prior to immunogenic challenge, showing that hapten and carrier act on different cells. When recognition was limited to one of the two cell types, paralysis resulted in accordance with predictions made on the basis of a two cell model of immune induction.