Homocytotropic and hemagglutinating antibody responses were followed in multimammate rats (Mastomys natalensis) infected with Brugia pahangi. Homocytotropic antibodies were detected by both active and passive cutaneous anaphylaxis using an antigen prepared from Dirofilaria immitis. The homocytotropic antibody response was first evident at 3 weeks after infection and increased progressively until after patency. It then waned gradually and was absent at 33 weeks after infection (or 20 weeks after patency). During this time microfilaremia continued to increase steadily. Homocytotropic antibody induced by the infection was heat (56° C) labile, sensitive to 2-mercaptoethanol reduction, and was detected in the skin of recipients following a 72-hour latent period. Hemagglutinating antibodies to the infection were detected by the D. immitis antigen. These were present by 9 days after infection and persisted throughout the course of the infection. Only 2-mercaptoethanol labile antibody was detected during the prepatent period of infection.
Present address: Clinical Unit, Tufts New England Medical Center, 171 Harrison Avenue, Boston, Massachusetts 02111.