COXSACKIEVIRUS B3-INDUCED CHRONIC MYOCARDITIS IN MOUSE - USE OF WHOLE-BLOOD CULTURE TO STUDY THE ACTIVATION OF TNF-ALPHA-PRODUCING CELLS

The pathogenesis of CVB3-induced chronic myocarditis remains unknown. Activated monocytes and macrophages may maintain ongoing inflammation during a persistent CVB3 infection and possibly represent the major me chanism leading to chronic myocarditis, We decided to study the activa tion status of cells by studying TNF alpha secretion in vitro using wh ole blood culture in CVB3-induced murine chronic myocarditis. Seven DB A/2 +/+ mice and 18 NMRI nu/nu mice were inoculated intraperitoneally with 5 x 10(5) pfu of CVB3, and mice were mock-infected, Thirty-one da ys post-infection, all mice were sacrificed, blood samples were obtain ed from the heart, and the heart was removed, Enteroviral genomic dete ction by RT-PCR, virus isolation and histological analysis of heart sa mples were performed, Heparinized whole blood (25 mu l) was cultured f or 4 hr and 24 hr in sterile 96 well-plate containing 225 mu l RPMI in the presence or the absence of activators (LPS+PHA). The TNF alpha le vels in the whole blood from mock-infected DBA/2 (n=4) and NMRI nu/nu mice (n=5) were not different, A moderate increase of TNF alpha was ob served in three out of five DBA/2 mice with negative CVB3 that had no histological abnormalities in myocardium. An increased level of TNF al pha was found in the sole DBA/2 mouse with positive CVB3 detection and chronic myocarditis, An increased level of TNF alpha was found in one out of nine NMRI nu/nu mice with positive CVB3 detection and chronic myocarditis and in one out of seven mice with positive CVB3 detection exempt of lesions in myocardium. In other infected mice, the level of TNF alpha was normal, Enteroviral genome was not detected in the blood from infected mice at 31 days post-infection, The increased TNF alpha level in some mice may be designed for a beneficial inflammatory and immune response, however, an exaggerated release may be associated wit h an adverse effect. The normal TNF alpha level in whole blood culture s from mice with chronic myocarditis does not exclude enhanced cytokin e production at infected loci such as myocardial tissue, This is the f irst report to use whole blood cultures to study the production of cyt okines in virus-induced disease in a small animal model.