Function and "homing" of the lung macrophages. I. Evidence of functional heterogeneity of mobile cells of the murine lung parenchyma in the bronchoalveolar lavage (BAL)

Abstract

The object of the present investigation was to extend fundamental understanding of the composition, function and origin of bronchoalveolar lavage (BAL) cells, and to reduce the considerable gaps in our existing knowledge. BAL cells from the B10.D2 mouse were identified by morphological, enzyme cytochemical and immunocytochemical methods and a further functional characterisation of macrophages was undertaken in vitro using latex phagocytosis. The possible bone marrow origin of BAL cells was investigated with a radiation chimera. The bone marrow from H2k-positive F1 mice (B10.BR x B10.D2) was transplanted into the irradiated H2k-negative parent animals. At various time intervals after transplantation, BAL cells were tested immunocytochemically for the presence of H2k-positive cells. The principal finding was that BAL cells are functionally heterogeneous. It was possible by morphological, enzyme cytochemical and immunocytochemical techniques to subdivide the total BAL cell count into 89% macrophages, 8.5% lymphocytes and 2.5% granulocytes. Only 14.3% of the macrophages expressed the corresponding epitope, and this small population could be further subdivided immunocytochemically into mature and immature (7:1) macrophages. The ability to phagocytose, which is typical of active macrophages, could be induced in vitro in only one-third of all BAL macrophages. Three-quarters of the macrophages carried the H2d antigen and 9.5% of the BAL cells were natural killer cells showing a macrophage phenotype. Subdivision of the lymphocytes showed a significant majority of T-cells (75%) to B-cells (20%), and 5% Asialo GM1-positive cells. The CD4/CD8 ratio amounted to 1.3:1 and 38% of the lymphocytes expressed on the surface the H2d antigen.(ABSTRACT TRUNCATED AT 250 WORDS)