Abstract
Abstract
The effects of recombinant tumor necrosis factor (rTNFα) on the immune responses were investigated. A single iv injection of rTNFα (6 × 103U) caused regression of sarcoma-180 transplanted into BALB/c nu/+ mice, but failed to regress this tumor in nu/nu mice. A higher dose of rTNFα (2 × 104U) was necessary to induce antitumor effect in nu/nu mice. A host-related factor seemed to be involved in mediating tumor regression. Therefore, the effects of rTNFα on various T-dependent immune responses, including delayed footpad reaction (DFR), cell mediated cytolysis (CMC), and plaque-forming cells (PFC) were examined in BALB/c mice, immunized ip with chicken erythrocytes (CRBC). A single injection of rTNFα, at the time of the antigen administration, induced the augmentation of CMC to CRBC in a dose-dependent manner. DFR and PFC were not affected in optimal immunization procedures. The TNFα injection, at or after the time of antigen administration, was more effective in inducing augmentation of CMC. The increase in CMC by TNFα was mediated by nonadherent, Thy 1.2, Lyt 2.2 positive cells and neutralization of TNFα by the anti-TNFα monoclonal antibody abolished the effect on CMC. These results indicated that the human recombinant TNFα induced Changes in the T-Cell-mediated responses.
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