Morphogenesis and pathogenesis of chronic lung diseases. VIII. Cellularization of lung interlobular areas as a preliminary phase of peribronchovascular fibrosis.

An experimental investigation of the lung interlobular areas was performed by elicitation of rabbits with antigens (aspergillar and human-serum proteins) administered in aerosols or intramuscularly in Freund's adjuvant. The cell accumulations in the interlobular areas developed irrespective of the antigen, duration of exposure and route of administration. The cells accumulated (reticulo-lymphoid, plasma cells, eosinocytes) were counted and the areal surface measured. The total cell count and the proportion of plasma cells appeared to be related to time, dose and antigenicity of the proteins administered. Fibrillogenesis was also observed between cells in the interlobular areas during prolonged administration of antigens, pointing out the importance of the interlobular lesions in chronic lung processes.