Mononuclear cell pulmonary vasculitis in NZB/W mice. II. Immunohistochemical characterization of the infiltrating cells.

NZB/W mice spontaneously develop pulmonary lymphoid hyperplasia and vasculitis in an age-related fashion. The cellular infiltrates and pattern of involvement bear similarity to various forms of pulmonary vasculitis in humans. In this study the authors used monoclonal antibodies and the avidin-biotin immunoperoxidase technique to analyze the pulmonary mononuclear cell infiltrates of female NZB/W mice at various ages and levels of disease activity. T cells, T-cell subsets, B cells, and Ia-bearing cells were localized with this technique. Most cells within the infiltrates were T cells that expressed the Lyt-1 phenotype, whereas cells expressing Lyt-2 were rarely observed. Cells reacting with a monoclonal antibody which recognizes cells of the B-lineage and cells expressing Ia antigens were also observed. Before the development of vasculitis, B and T cells were randomly distributed throughout the lesion. In older animals with vasculitis, T cells expressing Lyt-1 were associated with vessel lumen and were primarily responsible for the vascular infiltration, to the apparent exclusion of other lymphoid cell types. The B cells and Ia+ cells were localized at the periphery of the lesions.