Induction of CD4/CD8 DP monocytes in nontransgenic rats. (A) Myocarditis was induced in FW-wt rats by immunization with porcine cardiac myosin and the adjuvant containing killed tuberculosis germs at 3 weeks of age (immunized FW-wt). Peripheral blood was obtained from the FW-wt rats one week after immunization and age-matched controls and then PBMCs in region 1 (R1) were gated as in Figure 1. In both types of rats, the majority of CD4^medium cells did not express CD3, thus they were considered to be monocytes. In each group, at least 3 rats were examined. Representative data are shown. (B) The expression of CD8 on peripheral monocytes (practically CD4^medium cells) was examined 1 week and 4 weeks after immunization (4 and 7 weeks of age, respectively). Data were compared with those of nonimmunized FW-wt (control FW-wt) and FW-pX rats. In each group, at least 3 rats were examined. Representative data are shown. (C) The percentage of CD8⁺ cells in monocytes 1 week and 4 weeks after immunization (4 and 7 weeks of age, respectively) is shown as mean ± SD. (D) Inbred F344 rats (3 weeks of age) were immunized with various combinations of components used for the induction of myosin-induced myocarditis. The percentage of CD8⁺ cells in monocytes was examined 1 week after immunization. In each experiment, at least 3 rats were used. Data are represented as mean ± SD. FIA indicates Freund incomplete adjuvant; Killed G, killed tuberculosis germs. (E) PB-MCs from F344 rats (3 weeks old) were incubated with IL-12, RANTES, or GM-CSF under indicated concentrations. We chose these cytokines because they are known to be induced by BCG.^31-33  Twenty-four hours later, the percentage of CD8⁺ cells in monocytes (practically CD4^medium cells) was examined. Data are represented as mean ± SD of repeated experiments done in triplicate. ^*P < .05.