Platelet depletion lowers CTL response. (A) Mice were more than 99% depleted of platelets by intravenous injection of platelet-depleting monoclonal antibody and immunized with 106 pfu Ad5-mOVA intravenously 24 hours later. After 14 days, spleens were harvested for lytic assays. Data are representative of 4 experiments of 3 mice per group. (B) Immunodepletion of platelets does not release active sCD154. Mice were depleted of platelets as in panel A and platelet-poor plasma was harvested 24 hour later, the time at which adenovirus is injected for initiation of the immune response. Since commercial reagents with sufficient sensitivity are not available for the detection of murine sCD154 protein, plasma was bioassayed for activity as described in “Methods.” MS-1 cells were incubated for 6 hours with plasma from normal or depleted mice in the presence of MR1, a potent blocking monoclonal antibody against full-length or soluble murine CD154, and were assessed for MCP-1 mRNA content. Values were normalized and are expressed as stimulation index.
