Nonspecific allergic granulomatosis in the lungs of mice infected with large but not small inocula of the canine ascarid, Toxocara canis.

Infection of CBA/J mice with 250 ova of Toxocara canis results in development of splenic lymphocytes hyperergic to nonspecific stimuli. These studies were performed to see if the granulomatous response to a nonspecific stimulus was exaggerated. Using eosinophil counts and MBSA ear thickening it was demonstrated that concurrent infection with the parasite and immunization with methylated bovine serum albumin (MBSA) elicit no immunologic cross reactions. Eosinophil counts were proportional to the worm burden and unaffected by concurrent MBSA immunization. Embolization of Sepharose 4B beads conjugated to MBSA into the pulmonary vasculature of MBSA-immune mice, elicited large, florid macrophage-rich granulomata while in MBSA-naive mice infected with 10 T. canis ova, the beads elicited small, foreign body reactions. In MBSA-naive mice infected with 250 T. canis ova MBSA-coated beads elicited eosinophil-rich granulomata that were as large or larger than the granulomata in MBSA-immune mice. In mice immune and infected, lesions contained eosinophils in proportion to larval worm burdens. Because MBSA beads elicited large, eosinophilic granulomata in T. canis infected, MBSA-naive mice it is concluded that the lung is hyperergic and the disease process appears similar to other kinds of eosinophilic pneumonitis such as bronchial asthma or Loeffler's pneumonia.