FIG. 1.

Paneth cell secretion of bactericidal peptide activity in response to live bacteria. Individual crypts and villi were isolated from mouse small intestine, and numbers of each were incubated with 1,000 CFU of ΔphoP serovar Typhimurium cells at 37°C for 60 min in the presence of 1, 5, or 20 intact individual crypts or sheets of villus enterocytes (see Materials and Methods). Surviving bacteria were quantitated by plating incubation mixtures on nutrient plates, and replicates are shown. Symbols: ⋄, bacteria incubated but not exposed to crypts or villi; ▴, bacteria exposed to villus epithelium; ○, bacteria exposed to intact crypts.