Protective role of IgE in immunocompromised rat toxoplasmosis.
In contrast to euthymic adult Fischer rats, immunocompromised Nu/Nu animals develop a lethal infection when inoculated with the RH strain of the protozoan Toxoplasma gondii. However, a significant period of survival is obtained when Nu/Nu rats are passively transferred with sera from 28-day infected Fischer +/+ (euthymic) animals. Specific IgE are involved since IgE-depleted sera are unable to afford such a protection. Only excreted/secreted Ag or living tachyzoites are able to induce a significant protective IgE response in intact animals. In addition, platelets or, to a lesser extent, eosinophil-rich populations from Toxoplasma infected or excreted-secreted Ag-immunized euthymic animals bear surface IgE and are cytotoxic for the parasite in vitro. Also, adoptive transfer of immune platelets confers a significant degree of protection to Toxoplasma-infected Nu/Nu animals. Our results clearly show the key role of Ag present in both living parasites and excreted-secreted Ag to induce, in this model, a protective IgE response. In addition, as in other parasitic infections, platelets and probably eosinophils are the effector cells involved in controlling parasitic dissemination during Toxoplasma infection in immunocompromised rats.
Ridel
P R
PR
Centre d'Immunologie et de Biologie Parasitaire, Institut Pasteur, Lille, France.
Auriault
C
C
Darcy
F
F
Pierce
R J
RJ
Leite
P
P
Santoro
F
F
Neyrinck
J L
JL
Kusnierz
J P
JP
Capron
A
A
D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D001792:Blood Platelets / Q000276:immunology; D004804:Eosinophils / Q000276:immunology; D007106:Immune Sera / Q000008:administration & dosage; D007113:Immunity, Innate; D007116:Immunization, Passive; D007073:Immunoglobulin E / Q000032:analysis / Q000502:physiology*; D007074:Immunoglobulin G / Q000032:analysis; D008264:Macrophages / Q000276:immunology; D017713:Platelet Transfusion; D051381:Rats; D011916:Rats, Inbred F344; D011923:Rats, Nude; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D014124:Toxoplasmosis, Animal / Q000097:blood / Q000276:immunology*
D007106:Immune Sera; D007074:Immunoglobulin G; D011947:Receptors, Antigen, B-Cell; D007073:Immunoglobulin E