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Serodiagnosis of human toxocariasis
516
TRANSACTIONS OF THE ROYAL
SOCIETY OF TROPICAL MEDICINE AND HYGIENE (1987) 81, 516
Serodiagnosis of human toxocariasis H. V. SMITH, A. HAINSON, R. W. A. GIRDWOOD Dept
of Bacteriology, Stobhill General Hospital, Glawow. G21 3UW. UK We read with i&e&t the article by NICHOLAS et al.
(1986) on the seromevalenceof toxocaral antibodies in blood’ donors in’ Australia. In an enzyme-linked immunosorbent assay(ELISA) using excr&ory-secretory (ES) antigens of in vitro maintained second stage Toxocaru canis larvae. 7.5% of sera had antibodv reactive with ES. This observed percentage was feit by the authors to be “a little too high in comparison to previous work”. With this we concur. A consequence of infection with T. canis larvae is the production of isohaemagglutinins at high titres (HUNTLEY et al., 1965)mainly to A and B human erythrocyte antigens. The ES used for serodiagnosis has been shown to contain human A and B blood group-like antigens (SMITH et al.. 1983). These eDitoDes can interfere bith the accirate serological hetiction of human toxocariasis (SMITH et al., 1984a), as isohaemagglutinins produced in responseto other A blood group-like antigens are likely to cross-react. Further analyses of ES have demonstrated blood group reactivity associated with the 120 kDa molecule, using Helix pornaria lectin (MEGHJI & MAIZELS, 1986), and associatedwith the 70 kDa molecule using anti-A aqd anti-B blood group typing sera (H.V. Smith et’al., in preparation). It is likely that some of the Canberra blood donors have been exposed to or infected with T. canis larvae at one time or another; however, the proportion is debatable. It is as likely that sera from blood donors with elevated isohaemagglutinins (anti-A and/or antiB) due to other (bacterial not toxocaral) stimuli would account for a proportion of the seropositivity encountered in the blood donor group. We have observed positive reactions between A and B blood group typing sera by ELISA (unpublished) using antihuman antibodies to IgM, IgG and IgA isotypes. For the blood donors who provided sequential sera and whose ELISA ODdlo values exceeded the threshold for positivity, the same could be argued. However, preliminary results, using untreated ES, indicate that a higher specificity is obtained when IgE specific anti-human antibodies are used to develop the ELISA (OLIVER et al., 1986). It is not known whether the purified antigen of SUGANEand OSHIMA (1983) would provide a better
diagnostic antigen than ES. NICHOLAS et al. (1986) state that similar results were obtained using both antigens. It is unclear whether the use of the “nurified glyciprotein antigen” would reduce or ablate blood cross-reactivity. Although Helix pomatia lectin does not react with a similar 32 kDa molecule in ES, this molecule is recognized by a murine anticarbohydrate monoclonal antibody (MAIZELS et al., 1983) which has human A, blood group reactivity (SMITH et al., 1984b). Thus isohaemagglutinin cross-reactivity may be as likely with this “purified glycoprotein antigen” as with unfractioned ES. Further biochemical and immunological analysesof ES should provide an antigen free of such cross reactions for the diagnosis of human toxocariasis. References Huntley, C. C., Costas,M. C. & Lyerly, A. (1965).Visceral larva migrans syndrome: clinical characteristicsand immunologicalstudies in 51 patients. Paediatrics, 36, 523-536.
Maizels,R. M., Kennedy,M. W., Meghji, M. & Smith, H. V. (1983).Carbohvdrateandoroteindeterminantsof the suriace&d secretedantigens.ofToxocara canis infective larvae. Parasitology, 87, xlv. Meghji, M. & Maizels,R. M. (1986).Biochemicalproperties of larval excretory-secretory glycoproteinsof the parasite nematodeToxocara canis. Molecular and Biochemical Parasitology,
18, 155-170.
Nicholas, W. L., Stewart?A. C. & Walker, J. C. (1986). Toxocariasis:a serologIcasurveyof blood donorsin the Australian CaDitalTerritorv toeetherwith observations on the risksbiinfection. Tr&sa&ms of the Royal Society of Tropical Medicine and Hygiene, 80, 217-221.
Oliver, S. T., Cousland,G.. Smith, H. V. & Girdwood,R. W.’ A. (1987). Aitibddy isotype reactivity, iso&pe specific serodiagnosisand IgE antibody specificity in humansinfectedwith Toxocara canis larvae. Transactions of the Royal Societyof Tropical Medicine and Hygiene, (in press). Smith, H. V., Kusel, J. R. & Girdwood, R. W. A. (1983). The production of human A and B blood group like subst&ces by in vitro maintained second stage Toxocara canis larvae: their presence on the outer larval surfaces
and in their excretions/secretions.Clinical and Ew-
perimental Immunology, 54, 625-633.
Smith, H. V., Girdwood, R. W. A. & Kusel, J. R. (1984a) Misinterpretation of toxocaral serodiagnostic tests. British Medical Journal, 288, 1235. Smith, H. V., Maizels, R. M., Kennedy, M. W,., Meghji, M. & Ingleq, G. (1984b). Monoclonal anubodles to Toxocara cams excretory/secretory antigens have human A blood group reactivity. Parasitolo~, 89, xxxvii-xxxviii. Sugane, K. & Oshima, T. (1983). Purification and characterisation of excretory and secretory antigen of Toxocara canis larvae. Immunology, 50, 113-120. Accepted for publication
30 October
1986
TRANSACTIONS OF THE ROYAL
SOCIETY OF TROPICAL MEDICINE AND HYGIENE (1987) 81, 516
Serodiagnosis of human toxocariasis H. V. SMITH, A. HAINSON, R. W. A. GIRDWOOD Dept
of Bacteriology, Stobhill General Hospital, Glawow. G21 3UW. UK We read with i&e&t the article by NICHOLAS et al.
(1986) on the seromevalenceof toxocaral antibodies in blood’ donors in’ Australia. In an enzyme-linked immunosorbent assay(ELISA) using excr&ory-secretory (ES) antigens of in vitro maintained second stage Toxocaru canis larvae. 7.5% of sera had antibodv reactive with ES. This observed percentage was feit by the authors to be “a little too high in comparison to previous work”. With this we concur. A consequence of infection with T. canis larvae is the production of isohaemagglutinins at high titres (HUNTLEY et al., 1965)mainly to A and B human erythrocyte antigens. The ES used for serodiagnosis has been shown to contain human A and B blood group-like antigens (SMITH et al.. 1983). These eDitoDes can interfere bith the accirate serological hetiction of human toxocariasis (SMITH et al., 1984a), as isohaemagglutinins produced in responseto other A blood group-like antigens are likely to cross-react. Further analyses of ES have demonstrated blood group reactivity associated with the 120 kDa molecule, using Helix pornaria lectin (MEGHJI & MAIZELS, 1986), and associatedwith the 70 kDa molecule using anti-A aqd anti-B blood group typing sera (H.V. Smith et’al., in preparation). It is likely that some of the Canberra blood donors have been exposed to or infected with T. canis larvae at one time or another; however, the proportion is debatable. It is as likely that sera from blood donors with elevated isohaemagglutinins (anti-A and/or antiB) due to other (bacterial not toxocaral) stimuli would account for a proportion of the seropositivity encountered in the blood donor group. We have observed positive reactions between A and B blood group typing sera by ELISA (unpublished) using antihuman antibodies to IgM, IgG and IgA isotypes. For the blood donors who provided sequential sera and whose ELISA ODdlo values exceeded the threshold for positivity, the same could be argued. However, preliminary results, using untreated ES, indicate that a higher specificity is obtained when IgE specific anti-human antibodies are used to develop the ELISA (OLIVER et al., 1986). It is not known whether the purified antigen of SUGANEand OSHIMA (1983) would provide a better
diagnostic antigen than ES. NICHOLAS et al. (1986) state that similar results were obtained using both antigens. It is unclear whether the use of the “nurified glyciprotein antigen” would reduce or ablate blood cross-reactivity. Although Helix pomatia lectin does not react with a similar 32 kDa molecule in ES, this molecule is recognized by a murine anticarbohydrate monoclonal antibody (MAIZELS et al., 1983) which has human A, blood group reactivity (SMITH et al., 1984b). Thus isohaemagglutinin cross-reactivity may be as likely with this “purified glycoprotein antigen” as with unfractioned ES. Further biochemical and immunological analysesof ES should provide an antigen free of such cross reactions for the diagnosis of human toxocariasis. References Huntley, C. C., Costas,M. C. & Lyerly, A. (1965).Visceral larva migrans syndrome: clinical characteristicsand immunologicalstudies in 51 patients. Paediatrics, 36, 523-536.
Maizels,R. M., Kennedy,M. W., Meghji, M. & Smith, H. V. (1983).Carbohvdrateandoroteindeterminantsof the suriace&d secretedantigens.ofToxocara canis infective larvae. Parasitology, 87, xlv. Meghji, M. & Maizels,R. M. (1986).Biochemicalproperties of larval excretory-secretory glycoproteinsof the parasite nematodeToxocara canis. Molecular and Biochemical Parasitology,
18, 155-170.
Nicholas, W. L., Stewart?A. C. & Walker, J. C. (1986). Toxocariasis:a serologIcasurveyof blood donorsin the Australian CaDitalTerritorv toeetherwith observations on the risksbiinfection. Tr&sa&ms of the Royal Society of Tropical Medicine and Hygiene, 80, 217-221.
Oliver, S. T., Cousland,G.. Smith, H. V. & Girdwood,R. W.’ A. (1987). Aitibddy isotype reactivity, iso&pe specific serodiagnosisand IgE antibody specificity in humansinfectedwith Toxocara canis larvae. Transactions of the Royal Societyof Tropical Medicine and Hygiene, (in press). Smith, H. V., Kusel, J. R. & Girdwood, R. W. A. (1983). The production of human A and B blood group like subst&ces by in vitro maintained second stage Toxocara canis larvae: their presence on the outer larval surfaces
and in their excretions/secretions.Clinical and Ew-
perimental Immunology, 54, 625-633.
Smith, H. V., Girdwood, R. W. A. & Kusel, J. R. (1984a) Misinterpretation of toxocaral serodiagnostic tests. British Medical Journal, 288, 1235. Smith, H. V., Maizels, R. M., Kennedy, M. W,., Meghji, M. & Ingleq, G. (1984b). Monoclonal anubodles to Toxocara cams excretory/secretory antigens have human A blood group reactivity. Parasitolo~, 89, xxxvii-xxxviii. Sugane, K. & Oshima, T. (1983). Purification and characterisation of excretory and secretory antigen of Toxocara canis larvae. Immunology, 50, 113-120. Accepted for publication
30 October
1986