Saline extracts of ether-treated Dirofilaria immitis, Ascaris suum, and Ancylostoma spp. were used in indirect hemagglutination tests of serum from 164 patients with a diagnosis of eosinophilic lung and 114 persons with other diseases or no disease (blood donors). In the first group, positive reactions with one, two or all three antigens were obtained in 89 percent of cases and the titers, at medium or high levels in 77 percent, decreased after treatment with diethylcarbamazine. In the other group, antibodies were demonstrable in the serum of only 22 percent of cases and titers usually were low. These observations indicate the presence of several antigen-antibody systems, some of which appear to be specific. With extracts of Dirofilaria the indirect hemagglutination and the complement-fixation tests were similar in sensitivity and specificity, but the results from neither test appeared to indicate infection with a specific worm.
Sera taken fortnightly from fourteen patients with eosinophilic lung (tropical eosinophilia) were tested by complement fixation with ethanol extracts of Dirofilaria immitis, Ascaris lumbricoides, Toxocara canis, Gnathostoma procyonis, Fasciola gigantica and Dipylidium caninum. Initially, sera from ten patients had high antibody titers with each of the extracts while antibodies were not detected in sera from the other four; after treatment with diethylcarbamazine the high titers decreased. It is concluded that the reactions obtained with these various extracts do not indicate infection with any particular helminth.
The diverse clinical syndromes characterized by asthmatic symptoms, transient pulmonary infiltrates, and eosinophilia have tended to obscure the specific association of one such entity with filarial infections. Serum IgE levels were determined before and after therapy in a group of well-characterized patients with tropical eosinophilia (TE), studied earlier in Singapore. The mean serum IgE level in 14 cases before treatment with diethylcarbamazine was 2,355 ng. per milliliter, with a trend but statistically nonsignificant decrease in levels to 600-1,000 ng. occurring 8 to 12 weeks after therapy. Leukocyte and eosinophil counts showed a rapid reduction after treatment, and although mean complement-fixing (cf) titers to Dirofilarial antigen tended to decrease, they were not significantly reduced until 5 to 6 weeks. The historical development of evidence supporting the filarial etiology of TE was reviewed. Many basic questions engendered by the clinical syndrome of tropical eosinophilia make it an excellent model for study of the immunopathology of parasitic infections.