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Dual antibody stimulation: role of monocyte products and activation requirements of T cell subsets
F Bettens1, C Walker, F E Maly
1Institute for Clinical Immunology, Inselspital, CH 3010 Bern, Switzerland.
Using the model of dual antibody stimulation (cross-linking anti-CD3 BMA030-F(ab')2 antibodies with subset specific anti-T cell antibodies, i.e., anti-CD4 or anti-CD8 antibodies) we investigated the role of monocyte products in eliciting IL2 production and asked whether T cell subsets differ in their activation requirements. We found that activation mechanisms of dual antibody stimulation were equal for CD4 and CD8 as well as CD4 CDw29 and CD4 CD45R T cell subsets: dual antibody stimulation was necessary to induce responsiveness to soluble monocyte products which trigger IL2 synthesis. IL2 production induced by soluble monocyte products was measured in CD4 and CD8 T cells as specific IL2 mRNA expression and with a biological assay. Combined actions of IL1 beta and TNF alpha were identified as active monocyte products as (a) treatment of LPS-stimulated monocyte supernatants with anti-IL1 beta and anti-TNF alpha antibodies abrogated the proliferation inducing effect of monocyte supernatants and (b) addition of rIL1 beta and/or rTNF alpha enhanced proliferation of T cells stimulated by dual antibody cross-linking. If both recombinant monokines were added simultaneously a potentiated proliferative effect was observed. Whereas rIL1 beta plus/or rTNF alpha sustained proliferation, only rIL1 beta but not rTNF alpha induced IL2 synthesis in T cell subsets stimulated by dual antibody cross-linking.
Using the model of dual antibody stimulation (cross-linking anti-CD3 BMA030-F(ab')2 antibodies with subset specific anti-T cell antibodies, i.e., anti-CD4 or anti-CD8 antibodies) we investigated the role of monocyte products in eliciting IL2 production and asked whether T cell subsets differ in their activation requirements. We found that activation mechanisms of dual antibody stimulation were equal for CD4 and CD8 as well as CD4 CDw29 and CD4 CD45R T cell subsets: dual antibody stimulation was necessary to induce responsiveness to soluble monocyte products which trigger IL2 synthesis. IL2 production induced by soluble monocyte products was measured in CD4 and CD8 T cells as specific IL2 mRNA expression and with a biological assay. Combined actions of IL1 beta and TNF alpha were identified as active monocyte products as (a) treatment of LPS-stimulated monocyte supernatants with anti-IL1 beta and anti-TNF alpha antibodies abrogated the proliferation inducing effect of monocyte supernatants and (b) addition of rIL1 beta and/or rTNF alpha enhanced proliferation of T cells stimulated by dual antibody cross-linking. If both recombinant monokines were added simultaneously a potentiated proliferative effect was observed. Whereas rIL1 beta plus/or rTNF alpha sustained proliferation, only rIL1 beta but not rTNF alpha induced IL2 synthesis in T cell subsets stimulated by dual antibody cross-linking.