Fig. 5. Chronic otitis media, impaired macrophage activity and loss of peripheral lymph nodes in c^IBN mice. (A) Plastic sections of the middle ear of a wild-type littermate and a c^IBN mouse showing the middle ear cavity and the surrounding epithelium (arrowheads). Note the large amounts of pus and the swollen irregular mucous membrane in the middle ear of the c^IBN mouse (upper right panel). Magnified view of the mucous membrane surrounding the middle ear cavity (lower panels), showing large amounts of granulocytes and monocytes in the cavity, and infiltrations of granulocytes and monocytes in the mucous membrane of the c^IBN mouse (arrowheads). Arrowhead in wild-type (w.t.) points to a healthy mucous membrane. (B) c^IBN mice are more susceptible to Leishmania major infection. c^IBN mice (n=5; black square) and control littermates (n=3; white circle) were infected with L. major V121 promastigotes in the hind footpad. Data are expressed as mean increase in thickness compared with uninfected contralateral feet. (C) The higher susceptibility of c^IBN mice to L. major correlates with strongly reduced iNOS induction in bone marrow-derived macrophages after stimulation with TNF. The data are from three independent experiments. c^IBN mice (black square); wild-type littermates (white circle). Note that the error bars for c^IBN mice are smaller than the symbols and are not visible. (D) IFN production of spleen cells after restimulation in vitro with Leishmania antigens (lysate; see Material and Methods). For IFN production analysis after restimulation with L. major antigens (lysate) spleen cells were isolated from c^IBN or control mice infected with L.major for 8 weeks. Spleen cells were restimulated for 48 hours in the presence or absence of L.major antigens or were stimulated by Concanavalin A (ConA). IFN contents in culture were determined in a bioassay using WEHI-279 cells as described (Morris et al., 1992). Note the tenfold amount of IFN (U/ml) in IBN mice (black bars) when compared with control littermates (white bars). No difference is seen when the mitogen ConA or medium is added to the spleen cells.