Indirect effects of oral tolerance to ovalbumin interfere with the immune responses triggered by Schistosoma mansoni eggs.
The objective of the present study was to investigate whether the injection of a tolerated protein (indirect effects) affects the formation of granulomas around Schistosoma mansoni eggs trapped in the lungs after intravenous (iv) injection into normal (noninfected) C57BL/6 mice (6 animals per group). To induce oral tolerance to chicken egg ovalbumin a 1/5 dilution of egg white in water was offered ad libitum in a drinking bottle for 3 days. Control mice received water. After 7 days, control and experimental animals were injected iv with 2,000 S. mansoni eggs through a tail vein. In some mice of both groups the iv injection of eggs was immediately followed by intraperitoneal (ip) immunization with 10 micro g of dinitrophenylated conjugates of ovalbumin (DNP-Ova) emulsified in complete Freund's adjuvant (CFA) or only CFA; 18 days later, mice were bled and killed by ether inhalation. The lungs were fixed in formalin and embedded in paraffin. Serial sections of 5 m were stained with Giemsa, Gomori's silver reticulin and Sirius red (pH 10.2). Granuloma diameters were measured in histological sections previously stained with Gomori's reticulin. Anti-DNP and anti-soluble egg antigen (SEA) antibodies were analyzed by ELISA. In mice orally tolerant to ovalbumin the concomitant ip injection of DNP-Ova resulted in significantly lower anti-SEA antibodies (ELISA*: 1395 +/- 352 in non-tolerant and 462 +/- 146 in tolerant mice) and affected granuloma formation around eggs, significantly decreasing granuloma size (area: 22,260 +/- 2478 to 12,993 +/- 3242 m ). Active mechanisms triggered by injection of tolerated antigen (ovalbumin) reduce granuloma formation.
Carvalho
C R
CR
Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil. crochac@mono.icb.ufmg.br
Lenzi
H L
HL
Correa-Oliveira
R
R
Vaz
N M
NM
D000284:Administration, Oral; D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology*; D004140:Dinitrophenols / Q000008:administration & dosage / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006099:Granuloma / Q000276:immunology / Q000469:parasitology* / Q000473:pathology; D006241:Haptens / Q000008:administration & dosage / Q000276:immunology*; D007108:Immune Tolerance; D008174:Lung Diseases, Parasitic / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000008:administration & dosage* / Q000276:immunology*; D012550:Schistosoma mansoni / Q000276:immunology*
D000947:Antigens, Helminth; D004140:Dinitrophenols; D006241:Haptens; C045521:dinitrophenol-ovalbumin; D010047:Ovalbumin