FIG. 3.

T-lymphocyte apoptosis in peripheral LNs of SM and RM during acute SIV infection. (A) Percentage of active caspase-3-positive CD4⁺ and CD8⁺ T lymphocytes in LNs determined by flow cytometry. Means and standard errors of the means for SIVsmE041-infected SM (n = 2), SIVsmE041-infected RM (n = 4), and SIVmac239-infected RM (n = 6) shown. Asterisks denote P values of <0.01 as determined by the two-tailed unpaired t test. (B) Representative active caspase-3 IHC on LNs of one SIVsmE041-infected SM and one SIVmac239-infected RM before and 2 weeks after SIV infection. Caspase-3-positive cells (brown 3,3′-diaminobenzidine chromogen, indicated by the arrows) in the entire paracortical zone of the LN were counted and numbers were normalized relative to the entire LN section in mm². Plasma SIV RNA values are shown in parentheses. All sections are at a magnification of ×200 with hematoxylin counterstaining. (C) Absolute numbers of active caspase-3-positive T lymphocytes in LNs before and after SIV infection. Asterisks denotes P values of <0.05 as determined by the two-tailed paired t test.