Surface antigens of immunocompetent cells. 3. In vitro studies of the role of B and T cells in immunological memory.

The effect of preincubation with anti-theta or anti-mouse immunoglobulin (Ig) and complement (C') on immune responsiveness of spleen cells from BALB/c mice immunized with sheep erythrocytes (SE) was investigated. Both treatments greatly depressed the remaining ability to produce a secondary response to SE in vitro. Normal BALB/c spleen cells were far less effective in reconstituting the responses of such depleted cell populations than were much smaller numbers of untreated immune spleen cells. Thymus-derived cell (T cell) memory appeared early after immunization and showed specificity for the immunizing antigens. Recombination of anti-Ig-treated with anti-theta-treated immune spleen cells resulted in virtually complete reconstitution of responsiveness. The presence of immunological memory in T cells and the nature of their surface receptors are discussed.