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Figure 1 Nasal administration of CM reduced the severity of autoimmune myocarditis. (A) Female A/J mice were immunized subcutaneously twice on days 0 and 7 with porcine or murine CM (PCM or MCM) in complete Freund’s adjuvant for the induction of myocarditis. Three days prior to the first subcutaneous immunization with PCM (day –3), one group of mice (n = 9, open triangles) received a single nasal instillation of PCM, and the positive control group (n = 14, filled triangles) received equal volume of vehicle buffer. Three days prior to the first subcutaneous immunization with MCM, one group of mice (n = 9, open circles) received a single nasal administration of MCM, and the positive control group (n = 10, filled circles) received vehicle buffer only. All mice were sacrificed on day 21 when the heart sections were examined for evidence of myocarditis using the grading system described in the Methods section. The difference in severity between mice that received MCM intranasally and those that received vehicle buffer intranasally was statistically significant (p = 0.048). (B) Heart section from a PCM-immunized positive control mouse that received buffer intranasally and developed moderate myocarditis (grade 2.5) (24 x magnification). The inset on the top right corner is a closeup image (240 x magnification) of the cardiac infiltrate. (C) Heart section from the only mouse that developed cardiac infiltration in the group that received intranasal instillation of PCM (24 x magnification).