LETTER TO THE EDITOR

Rosario, March 19, 2002

P SYSTEM EPITHOPES IN Ascaris lumbricoides

Dear Editor,

The blood group P substances of tissue cells mediate the adhesion of a series of pathogenic bacterias (Escherichia coli, Streptococcus suis, Pseudomona aeruginosa, and de Shiga toxin of Shigella dysenteriae). Further, P (globoside) has been shown to be the cellular receptor for parvovirus B₁₉.

The antigens of the P system have also been detected in various animal species, where the characters occur not only on erythrocytes and tissue cells but also on water-soluble glycoproteins of secretions and body fluids¹⁰.

Strong P₁ (+ P^k) activity has been found in the ovomucoid of turtledove eggs³. Another excellent source for P₁ (+ P^k) active material is the fluid in hydatic cysts taken from sheep liver containing live protoscolices of the tapeworm Echinococcus granulosus¹. Further, P₁ specific substances were found in the extracts of earthworm Lumbricus terrestris⁷ and the roundworm Ascaris suum⁸.

Mimicry, antigenic modulation and natural selection have been proposed to explain hosts tolerance for a parasite⁹.

We worked with 27 Ascaris lumbricoides extracts [ AE ].

In order to perform our experiments [ AE ] were prepared. Adult specimens were washed in physiological solution supplemented with 200 mg /ml of streptomycin and 200 mg /ml of penicillin. After that a refrigerated mechanical rupture was performed for 5 days. The supernatants were collected and kept at –20ºC with a final concentration of timerozal 1:1000^2,5.

Inhibition agglutination tests were made facing the [ AE ] against anti P and anti P₁ monoclonal antibodies in optimal concentrations (lot No. 2-87 / lot No. 2-88 Monoclonal Antibodies against Blood Group Antigens. IV Workshop. Paris. July 2001). Suspensions of fresh red cells (P and P₁) were used as a revealing system⁴.

Results have shown that out of the 27 [ AE ] studied, 15 presented P and P₁ epithopes and only one [ AE ] P₁ epithope.

Previous studies have shown the presence of A and B antigens in the [ AE ] ⁶. Owing to the similarity between ABO system and P system, we conclude that membrane glycolipids would be involved in the escape mechanism of the immune response for Ascaris lumbricoides.

Bioq. Patricia PONCE DE LEÓN

Dra. Juana VALVERDE

Departamento de Microbiología

Laboratorio de Inmunohematología

Facultad de Cs. Bioq. y Farm.

Suipacha 531

2000 Rosario, Argentina.

Email: tefu1958@hotmail.com

REFERENCES

1. CAMERON, G.L. & STAVELEY, J.M. - Blood group P subtance in hydatic cyst fluid. Nature (Lond.), 179: 147-148, 1957.

2. CAPRON, A.; BIGUET, J.; VERNES, A. & AFCHAIN, D. - Structure antigénique des helminthes. Aspects immunologiques des relations hôte-parasite. Path. Biol., 16: 121-138, 1968.

3. FRANÇOIS GERARD, C.; BROCTEUR, J. & ANDRE, A. - Turtledove: a new source of P₁ like material cross-reacting with the human erythrocyte antigen. Vox Sang (Basel), 39: 141-148, 1980.

4. MARCELLI, A.; FINE, J.M. & RIBAT, I. - Techniques in Immunohematologie. Paris, Flammarion, 1981.

5. MONROY OSTRIA, A.; GOMEZ GUTIERREZ, L.J.; RAMIREZ RAMIREZ, A. & CARRILLO LANDIN,G. - Reconocimiento por inmunotransferencia de antígenos de Taenia solium y su larva. Rev. lat-amer. Microbiol., 34: 33-38, 1992.

6. PONCE DE LEÓN, P.; VALVERDE, J. & ZDERO, M. - Preliminary studies on antigenic mimicry of Ascaris lumbricoides. Rev. Inst. Med. trop. S. Paulo, 42: 295-296, 2000.

7. PROKOP, O. & SCHLESINGER, D. - Uber das vorkommen von P₁. Blut gruppen substanz oder einer P₁-like substance bei Lumbricus terrestris. Acta biol. Med. germ., 15: 180-181, 1965.

8. PROKOP, O. & SCHLESINGER, D. - Uber das vorkommen von P₁. Blut gruppen substanz order einer P₁-like substance bei Ascaris suum. Dtsch. Gesundh.-Wes., 20: 1584, 1965.

9. SALMON, C.H. - Les groupes sanguins ou l'écriture des genes. Paris, Masson, 1997.

10. SCHENKEL- BRUNNER, H.- Human blood groups. Chemical and Biochemical basis on antigen specificity. New York, Springer Verlagwiem, 2000.

Received: 19 March 2002

Accepted: 09 April 2002

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