FIGURE 3. B7-1 and B7-2 surface expression and mRNA expression following DNFB-mediated CHS responses in ribavirin-treated BALB/c (left panels) and C57BL/6 (right panels) mice. Ribavirin (5 mg/50 ml PBS) was injected i.p. at the time of 0.12% DNFB challenge. A, Cell surface expression of B7-1 and B7-2, 24 h post-DNFB challenge, was determined in isolated LNC of individual DNFB-primed mice (dashed lines) and DNFB-primed mice treated with ribavirin (solid lines). B7-1 and B7-2 expression was also determined in unprimed mice from respective strains (dotted lines). B7-1 and B7-2 levels were assessed by staining with FITClabeled Abs to B7-1 (CD80) and B7-2 (CD86), followed by FACS analysis of gated CD3-negative cells. The data shown are representative of three experiments using five mice per test group. B, B7-1 and B7-2 mRNA expression, 24 h post-DNFB challenge, was determined in total RNA isolated from the LNC of individual DNFB-primed mice and DNFB-primed mice treated with ribavirin. B7-1 and B7-2, IFN-a, and b-actin mRNA levels were assessed following RT-PCR and Southern blot analysis with specific 32P-labeled DNA probes. B7-1 and B7-2 mRNA expression in a mouse B cell lymphoma cell line, A20, was also determined as a control for the B7-1 and B7-2 primers. Autoradiography data are representative of two separate experiments using five mice per treatment group. C, The relative changes in B7-1, B7-2, and IFN-a mRNA from the mouse groups in B are presented as densitometric readings for Primed (hatched bars) and Primed 1 RIB (solid bars) mouse groups and normalized for any variations in input RNA by determining the densitometric ratio of mRNA of interest relative to mRNA of b-actin. Data are mean 6 SD from a pool of five per group. p, BALB/c, p 5 0.004; C57BL/6, p 5 0.009.