Reduction in the Severity of Mycoplasma Pneumoniae-Induced Pneumonia in Hamsters by Immunosuppressive Treatment with Anti-Thymocyte Sera

Abstract

Summary Intranasal inoculation of Mycoplasma pneumoniae into hamsters caused pneumonia characterised by peribronchial and perivascular cuffing by lympho- cytes. Hamsters immunosuppressed by treatment with anti-thymocyte serum developed a much less severe pneumonia. The numbers of organisms isolated from the lungs of immunosuppressed animals were greater than those obtained from the lungs of immunologically normal animals but there was no evidence that extrapulmonary spread occurred. These results indicate the importance of cell- mediated mechanisms in the pathogenesis of this mycoplasma-induced pneumonia. The hamster model may help to establish the role of cell-mediated immunity in resistance to this type of infection. We thank Mr G. F. Heath and Mrs Sharon Veal for technical assistance, the staff of the Department of Pathology, Clinical Research Centre, for preparation of histopathology sections and Dr A. C. Allison for a supply of anti-thymocyte serum.