Lanthanum penetration of the trachea after the immediate response of sensitized rats to aerosol antigen.

Inbred rats were sensitized by the intraperitoneal injection of 10 micrograms DNP19-ovalbumin (DNP-OA). These rats were compared both in their responses to 10 min of aerosol challenge with DNP-OA or bovine gamma globulins (BGG) and with other rats similarly 'sensitized' with saline and subsequently challenged with DNP-OA. Lanthanum (1%) in the fixative permitted the identification by transmission electron microscopy of electron-dense lanthanum in the tracheal epithelium. Planimetry showed 59% of the intercellular membranes in the tracheal epithelium of the group sensitized and challenged with DNP-OA were stained with lanthanum versus 39% in the saline-sensitized and 26% in the BGG-challenged. X-ray energy probe microanalyses confirmed that significantly more lanthanum had penetrated in the group sensitized and challenged with DNP-OA than in the other two groups. In this group the magnitude of the change in respiratory pattern produced by challenge was directly related to the quantity of the lanthanum in the epithelium. Our findings show that increased permeability of the intercellular spaces occurs in immediate pulmonary hypersensitivity, probably as a result of the opening of the tight intercellular junctions and suggests that this change of permeability may be involved in producing the physiological response.