Functional analysis of lymph node T cells isolated from T-lymphopenic rats treated as in Figure 2B with CD28 superagonist or vehicle 2 months earlier. (A) Representation of endogenous (CD45^–) and transferred (CD45^b+) T cells. (B) Assessment of in vitro proliferative capacitiy to immobilized anti-TCR plus soluble anti-CD28. (C) Cytokine production by in vitro–costimulated cells.