We have evaluated the nature of Aschoff cells within
Aschoff bodies seen in 35 of 100 excised left atrial appendages from cases of rheumatic
mitral stenosis who underwent closed mitral valvotomy. These were tested using a panel of monoclonal and polyclonal
antisera by the indirect immunoperoxidase staining for leucocyte common
antigen, macrophage,
desmin,
vimentin, alpha-1-antitrypsin, alpha-1-antichymotrypsin,
lysozyme,
acid phosphatase and
nonspecific esterase. The Aschoff cell gave strong reactivity with monoclonal
antisera to
vimentin, macrophage and variable reaction with polyclonal
antisera known to recognise macrophages/histiocytes in tissues, namely alpha-1-antitrypsin, alpha-1-antichymotrypsin and
lysozyme. These were also strongly positive for
acid phosphatase and
nonspecific esterase. The Aschoff cell lacked affinity for
desmin and only an occasional cell in 4 out of 20 and 6 out of 35 cases showed a weak reaction with
myoglobin and leucocyte common
antigen, respectively. Intense consistent reactivity with several histiocytic markers affirms the genesis of these cells from macrophages/histiocytes and not muscle cells; a controversy which must be laid to rest!