Bronchoalveolar lavage cell analysis in measles viral pneumonia

Although the immunological changes due to measles virus infection, such as suppression of delayed skin reactivity and increase in soluble CD8 in peripheral blood, have been demonstrated, the immunological changes in the lung during measles viral pneumonia (MVP) have not been reported. The aim of this study was to clarify the intrapulmonary immunological changes in MVP. We analysed cell differentials and lymphocyte surface antigens of bronchoalveolar lavage (BAL) cells, both in the acute and the convalescent phase of MVP by flow-cytometry, using CD4+, CD8+, CD8+CD11b+ and CD8+CD11b- monoclonal antibodies in five patients and six healthy control subjects. The absolute numbers of CD8+ and CD8+CD11b- cells were significantly greater both in the acute and the convalescent phase compared with those in controls. The percentages of CD8+ and CD8+CD11b- cells in the acute phase were significantly greater than those in controls and the convalescent phase. The CD4/CD8 ratios in the acute phase were significantly smaller than those in the convalescent phase and controls. In conclusion, the intrapulmonary immunological changes with an increase in CD8+ and CD8+CD11b- cells in BAL fluid of MVP are thought to be the primary reaction in measles virus-infected lungs.