Study on lymphocyte-response in early stage of respiratory infection--a view point from experimental Klebsiella pneumoniae pneumonia

Abstract

This study was performed to demonstrate the early immuno-responses of lymphocytes in an experimental pneumonia with K. pneumoniae in mature mice (45 week-old) comparing with it in juvenile ones (4 week-old). Acute mice pneumonia was made by inhalation with K. pneumoniae DT-S strains into lung. Changes in lymphocytes including their subpopulation in bronchoalveolar lavage fluid (BALF), peripheral blood, hilar lymphnodes and lung tissue were observed after the inhalation. In addition, lung tissue and hilar lymphnode were examined immunohistologically. The following results were obtained: 1. Total lymphocytes in BALF were more rapidly increased in the mature group than in the juvenile one. But there was no significant change in leukocyte count in peripheral blood between both groups. 2. Such a rapid increase in lymphocytes in BALF in mature group depended on L3T4-Ly6c cells and L3T4-LFA 1 cells. These cells in juvenile group were not accumulated in BALF at initial phase of the infection. But in contrast, they were gradually increased in peripheral blood and in hilar lymphnode. There was significant time-differences in appearance of these cells in BALF between both groups. It might be, that L3T4-Ly6c cells and L3T4-LFA1 cells observed in BALF in mature animals were induced from bronchus-associated lymphoid tissue (BALT) or small lymph tissue in alveolar interstitium, but in juvenile ones were originated in hilar lymphnode. 3. Changes in Ly2-Ly6c cell and Ly2-LFA1 cell were shown the same tendency changes in L3T4-Ly6c cell and L3T4-LFA1 cell. 4. Accumulation of B220:Ly5-LFA1 cell in BALF was not observed in significant difference between the mature group and in the juvenile one. 5. L3T4 cells were markedly accumulation in subcortex area of hilar lymphnode in the juvenile group, but they were only seen scattered in the mature group. 6. It can be concluded that active T lymphocyte begins to response in situ in the early stage of respiratory infection in the mature host and this finding is a characteristic lymphocyte response, that is never seen in the juvenile group.