FIG. 4.

Depletion of CD8⁺ CTL decreases lysis of infected targets. PBMC from four horses were stimulated for 5 days with live virulent R. equi and then rested for 48 h. Stimulated PBMC were then depleted of CD4⁺ cells or CD8⁺ cells and used as effectors. (A) Autologous or (B) ELA-A mismatched PBACs infected with virulent R. equi 33701 (E:T ratio of 5:1). Uninfected PBAC targets served as negative controls. a, following CD8⁺ T-lymphocyte depletion of effectors, lysis significantly decreased (>3 standard errors) relative to the infected PBMC (undepleted) control.