To characterize responses at the earliest times after infections, lavage fluids and cells were collected from peritoneal cavities of B6 mice that had been uninfected or infected i.p. with 5 ϫ 10 4 PFU LCMV at the indicated times prior to harvest. The fluids were tested to evaluate cytokines released at the site. The IFN-␥ levels were measured using a cytometric bead assay (CBA). Low but consistently detectable levels of IFN-␥ were found peaking at 30 h after LCMV infection (Fig. 1A) . Enzyme-linked immunosorbent assays (ELISAs) were used to measure IFN-␣ and IFN-␤. In contrast to the reported extended kinetics of systemic levels of these cytokines (7, 9, 17) as well as the type 1 IFNs detected through 48 h after infection in serum samples taken from mice used for these experiments (data not shown), concentrations of IFN-␣ and IFN-␤ in the peritoneum reached their peak values of 340 and 69 pg/ml, respec-tively, at 30 h after challenge and were sharply confined to the 6-h periods surrounding that point (Fig. 1A) . The levels of IL-12p70, a known inducer of IFN-␥, were acquired from the CBAs. All samples were below the limit of detection for the assay, with no detectable levels in a large majority of samples isolated after 20 to 48 h of infection (Fig. 1A) . Thus, the peritoneal cytokine responses to LCMV infection include early induction of IFN-␥, with kinetically overlapping IFN-␣ and IFN-␤ production, but undetectable IL-12.