Histopathology of Brugia malayi-infected nude mice after immune-reconstitution.

Long term (greater than 200 day) Brugia malayi-infected nude mice with grossly dilated lymphatics were reconstituted with 10(8) primed spleen cells from heterozygous donors. Histological and ultrastructural examination at 7, 14, 21 and 28 days post-reconstitution revealed progressive fibrosis, obliterative lymph thrombus formation, interstitial infiltrates and extensive perilymphangitis. Formation of lymph thrombi/granulomas was associated with killing of adult worms and microfilariae, and the predominant cell types involved were large granular macrophages. Langhan's giant cells and eosinophils. Thus, the ability to initiate the formation of obstructive lesions in the dilated lymphatics of chronically parasitized nude mice by immunological reconstitution, suggests that several complex mechanisms might operate in stages to cause filarial elephantiasis.