Figure 2. T-Cell Responses to Vaccinia Virus Six Months after Vaccination with Undiluted Vaccine, a 1:10 Dilution of Vaccine, or a 1:100 Dilution of Vaccine, According to the Presence or Absence of Vesicle Formation at the Inoculation Site within Seven to Nine Days after Vaccination.

Panel A shows the cytotoxic T-cell responses. The actual values for two outliers are shown. Panel B shows the number of cells producing vaccinia virus–specific interferon-. Panel C shows the degree of lymphocyte proliferation in response to vaccination. Two subjects with vesicles, one each from the group given undiluted vaccine and the group given the 1:10 dilution, had nonviable peripheral-blood mononuclear cells (PBMC) and could not be tested in any of the cell-mediated immune assays, and one subject in the group given the 1:100 dilution who did not have vesicle formation did not have blood drawn. One subject each in the group given undiluted vaccine and the group given the 1:10 dilution who had vesicle formation had high background values in the cytotoxic T-cell assay, which prevented interpretation of the results (Panel A). The stimulation index is the mean of the three intermediate values in each replicate of five. Higher values indicate greater proliferation of lymphocytes. The number in parentheses indicates the number of subjects with a stimulation index of 1, all of whom received the 1:100 dilution. Dashed lines in Panels B and C indicate the cutoff values for a positive response.