Injection of microfilariae induces resistance to Brugia malayi infection in ferrets and accelerates development of lymphostatic disease.

Ferrets injected intravenously with living microfilariae or cutaneously with microfilariae followed by intravenous injection developed partial resistance to a challenge infection as measured by recovery of adult filariae from lymphatics. Following a challenge infection, the ferrets injected with microfilariae developed lymphatic pathology characteristic of a chronic infection or that observed following multiple infections. There was disruption of lymphatic drainage of the infected limb and lymphoedema. The results suggest that immune responses to antigens of microfilariae, presumably antigens shared with other developmental stages, effected both increased resistance and enhanced lymphatic pathology.

Peripheral lymphedema in ferrets infected with Brugia malayi.

This study examines the production and persistence of peripheral lymphedema in ferrets experimentally infected with Brugia malayi. In 14 of 18 ferrets inoculated 2 or more times with infective larvae, lymphedema developed in the inoculated paw or paw and lower leg. In 5 of these ferrets lymphedema had persisted for 8 to 18 months at the time of necropsy. Lymphedema rarely was observed following a single inoculation of larvae or in microfilaremic ferrets. The results suggest that the ferret may be a useful experimental animal for the study of chronic lymphostatic disorders in filariasis.

Antibody and cellular immune responses to microfilarial antigens in ferrets experimentally infected with Brugia malayi.

Eleven of 15 ferrets experimentally infected with Brugia malayi became amicrofilaremic after a brief patency; only four ferrets remained patent after 6 months of infection and two of these ferrets developed a high, persistent microfilaremia. Blastogenic responses of peripheral blood lymphocytes to antigens of microfilariae (mf), assayed in vitro, demonstrated an antigen sensitivity at prepatent, patent and postpatent periods of infection. Lymphocytes from ferrets with high microfilaremia had elevated background responses in culture which were directly correlated with the number of circulating mf. This background response was attributed to antigenic stimulation by mf present in the lymphocyte cultures; addition of mf to cultures of lymphocytes from postpatent ferrets induced responses equivalent to those observed in microfilaremic ferrets. Lymphocyte responses to the mitogen, concanavalin A, did not differ significantly among microfilaremic, amicrofilaremic and uninfected ferrets. Antibody in IgG to antigens of mf measured by ELISA and by immunoblots from SDS-PAGE showed similar patterns of response in ferrets which became amicrofilaremic and in the few ferrets which remained microfilaremic. prausnitz-Kustner tests demonstrated no consistent differences in titers to microfilarial antigens between patent and amicrofilaremic ferrets. The results suggest a high level of immune responsiveness to antigens of mf in infected ferrets with no evidence of immunosuppression associated with prolonged microfilaremia or of major changes in immune responses with development of amicrofilaremic infections.

Brugia malayi: intravenous injection of microfilariae in ferrets as an experimental method for occult filariasis.

Microfilaremia, immune responses, and pathology were compared in ferrets infected with 100 third-stage larvae of Brugia malayi (subperiodic strain) or injected intravenously with 10(6) microfilariae. Ferrets (Mustela putorius furo) inoculated with third-stage larvae typically became patent during the third month after infection, with a mean patency of 123 +/- 25 (SE) days. Ferrets injected intravenously with microfilariae exhibited a relatively constant microfilaremia for 3-4 weeks and usually cleared microfilariae before the fourth month. Ferrets that cleared microfilariae after intravenous injection of microfilariae or after infection with third-stage larvae failed to become patent or became amicrofilaremic within 3 weeks after a challenge intravenous injection of 10(6) microfilariae. Clearance of circulating microfilariae was associated with eosinophilia and serum antibody specific for the microfilarial sheath in ferrets injected with microfilariae and in most ferrets infected with third-stage larvae. Ferrets infected with third-stage larvae and necropsied after clearance of microfilariae had tissue inflammatory reactions to microfilariae characteristic of occult filariasis (tropical eosinophilia) in man; these ferrets exhibited immediate cutaneous hypersensitivity and circulating reaginic antibody to antigens of microfilariae. In ferrets necropsied following two intravenous injections of microfilariae, the majority of ferrets examined within 10 days after clearance of microfilariae had visible liver lesions to microfilariae identical to those of the ferrets infected with third-stage larvae; immediate cutaneous hypersensitivity and reaginic antibody were not consistently detected in ferrets injected with microfilariae. Sera from ferrets that had cleared circulating microfilariae were transferred passively into ferrets made microfilaremic by intravenous injection of microfilariae. Sera with microfilarial sheath-reactive IgG antibody titers (greater than or equal to 1:200) and microfilarial agglutination titers (greater than or equal to 1:40) rapidly cleared injected microfilariae (less than 24 hr); this serum also cleared or greatly reduced circulating microfilariae established by an infection with third-stage larvae; only the IgG-containing fraction of the sera was active in immune clearance. Sera that cleared microfilariae of B. malayi did not clear circulating microfilariae of Dirofilaria immitis or prevent recurrence of circulating microfilariae of B. malayi in ferrets infected with adult filariae.(ABSTRACT TRUNCATED AT 400 WORDS)

Pathology of experimental infection with Brugia malayi in ferrets: comparison with occult filariasis in man.

Ferrets experimentally infected with Brugia malayi (subperiodic strain) developed eosinophilia at patency and usually became amicrofilaremic. Ferrets necropsied within 3 months after becoming amicrofilaremic had granulomas and focal reactions to degenerating microfilariae in their livers, lungs and lymph nodes essentially identical to those of tropical eosinophilia. Four of 7 ferrets that received multiple inoculations of larvae, developed edema of the inoculated paw and leg after becoming amicrofilaremic and 6 of these 7 ferrets had granulomatous lymphangitis and lymphadenitis of inoculated limbs but not the lesions of lung and liver characteristic of occult infection.

The histology and ultrastructure of the Meyers-Kouwenaar body in ferrets infected with Brugia malayi.

A study was made of the Meyers-Kouwenaar (MK) body in the livers of experimentally infected ferrets. Meyers-Kouwenaar bodies, the carcasses of microfilariae (mff) covered by deposits of Splendore-Hoeppli (SH) material, were found in small abscesses of eosinophils and in granulomas. The SH deposits varied from an eosinophilic, hyaline fringe around intact mff to multilayered deposits surrounding an unrecognizable granular remnant. In abscesses, peroxidase activity was intense in SH deposits and the surrounding eosinophils. The presence and localization of IgG were variable in MK bodies, as detected by an enzyme-linked immunohistologic assay; and antigens of mff were not detected in the SH deposits. Electron microscopy of the MK body demonstrated a layered, radial deposition of amorphous and granular material on the mff and a structural heterogeneity which apparently included leukocyte granules and other cell organelles. Leukocytes surrounding MK bodies in abscesses were often degranulated and degenerate; incorporation of lysosomes of eosinophils and cellular debris into the SH deposits at the periphery of the MK bodies was indicated.

In vivo and in vitro responses to sheep erythrocytes by lymph node cells from mice with trichinellosis.

Mice infected with Trichinella spiralis for 20 days have decreased numbers of plaque forming cells (PFC) in the draining lymph nodes following subcutaneous immunization with sheep erythrocytes. However, when immunized in vitro, lymph node cells from infected mice generate more PFC than normal controls. Splenectomy has no effect on suppression observed in vivo. There is a large increase in the proportion and numbers of B cells in the lymph nodes of infected mice, and these cells may account for the enhanced PFC responses in vitro.

Antibody responses to experimental Brugia malayi infections in patas and rhesus monkeys.

Humoral antibody responses in experimental infections with Brugia malayi (subperiodic strain) were compared in two primate species. Erythrocebus patas and Macaca mulatta. Antibody responses were related to the infection protocol and the duration and magnitude of microfilaremia. Patas monkeys were uniformly susceptible to infection and characteristically exhibited prolonged microfilaremia; infections in Rhesus monkeys produced low and usually microfilaremia. Antibody, measured by enzyme linked immunosorbent assay with extracts of adult Brugia and microfilariae as antigens, declined at patency in Patas monkeys and there was an inverse relationship between serum antibody concentration and the number of circulating microfilariae. Rhesus monkeys generally had high, sustained antibody levels relative to Patas monkeys, but antibody levels were comparable in the two species when the numbers of circulating microfilariae were similar. By fluorescent antibody technique, antibodies reactive with somatic antigens of microfilariae were detected in all infected monkeys; antibodies reactive with the cuticle of infective larvae were also present in both primates and were consistently detected in monkeys receiving multiple infections. Antibodies (IgG, IgM) reactive with the sheath of microfilariae were detected only in certain Rhesus monkeys which were essentially amicrofilaremic and sera with antibodies specific for microfilarial sheath promoted in vitro microfilarial agglutination and leukocyte adherence.

The ferret (Mustela putorius furo) as an experimental host for Brugia malayi and Brugia pahangi.

Ferrets inoculated subcutaneously with 150--200 infective larvae of Brugia malayi (subperiodic strain) usually developed patent infection during the 3rd month post inoculation. Microfilaremia was transient, and most animals became amicrofilaremic after the 6th month of infection. Ferrets developed a persistent eosinophilia at the time of patency. At necropsy, 5--8 months post infection, adult worms were recovered principally from lymphatic vessels and recovery ranged from 0.5--13% of the inoculated larvae. The inflammatory response of ferrets to microfilariae was characterized by nodules 1--5 mm in diameter in the liver, lungs, spleen, and submucosa of the gastrointestinal tract. The center of these lesions contained a degenerated microfilaria or the cast of a microfilaria embedded in Splendore-Hoeppli substance. The Splendore-Hoeppli substance was surrounded by eosinophils and/or foreign body giant cells. Identical lesions were observed in ferrets experimentally infected with Brugia pahangi. Sera from ferrets infected with B. malayi demonstrated a 3- to 5-fold increase in IgG by the 4th month of infection and these sera produced 2--3 precipitin bands in double gel diffusion assays with an extract of B. malayi microfilarial antigen. Skin tests with B. malayi microfilarial antigen showed that the majority of the infected ferrets had immediate hypersensitivity responses, but none had Arthus or delayed hypersensitivity responses.

Serum immunoglobulin and antibody levels and the passive transfer of resistance in hamsters infected with Dipetalonema viteae.

Clearance of microfilariae from the circulation of hamsters infected with Dipetalonema viteae was demonstrated following passive transfer of serum obtained from hyperinfected hamsters. The exclusion fraction after gel filtration of this serum on Sephacryl S 200 also cleared microfilariae whereas the other fractions did not. There was no clearance with serum taken during the pre-patent, patent or latent periods of singly infected hamsters. IgM antibody to the microfilaria cuticle measured by the fluorescent antibody technique was increased 2 to 4 times in the protective serum over the other sera. Suppression of microfilaremia was also adoptively transferred by cells from infected hamsters. Serum Ig and antibody levels to microfilaria cuticle were measured in 3 strains of hamsters differing in their ability to clear microfilariae. IgM antibody to microfilaria cuticle correlated with the ability to clear. No IgG antibody to microfilaria cuticle was detected and the major Ig response to infection was in IgG1, which increased 10 to 20 fold.

Analysis of immunosuppression during early acute infection of mice with Ascaris suum.

Immunosuppression was examined at 10 to 12 days following oral inoculation of 10,000 to 12,000 embryonated Ascaris suum eggs. Reduced antibody responses to sheep red cells (SRC) following systemic immunization were confirmed in CD-1 and C57Bl/6 mice. Infection alone induced antibody reactive with DNP equivalent to that observed after immunization with DNP--Ficoll. There was a decrease in thymus and spleen size by day 8 of infection, followed by a splenic proliferative response during the second week. In the second week, serum antibodies reactive with SRC, chicken erythrocytes, DNP and bacterial lipopolysaccharide were demonstrated, suggesting polyclonal B-cell stimulation. The cellular basis of immunosuppression was investigated by in vitro culture of splenocytes from C57Bl/6 mice. Differential leucocyte counts of splenocytes before culture demonstrated a relative increase in plasma cells, blastoid cells, complement receptor-bearing lymphocytes and eosinophils, with a relative decrease in small lymphocytes. The splenocytes had reduced responses to T-cell mitogens, as measured by thymidine incorporation in vitro, and reduced antibody responses to SRC and DNP--Ficoll. In vitro, cell mixing experiments did not demonstrate suppressor cells in the spleens of infected mice.