Regulation of immunoglobulin E production in mice immunized with an extract of Toxoplasma gondii

Increased B Cell ADAM10 in Allergic Patients and Th2 Prone Mice

ADAM10, as the sheddase of the low affinity IgE receptor (CD23), promotes IgE production and thus is a unique target for attenuating allergic disease. Herein, we describe that B cell levels of ADAM10, specifically, are increased in allergic patients and Th2 prone WT mouse strains (Balb/c and A/J). While T cell help augments ADAM10 expression, Balb WT B cells exhibit increased ADAM10 in the naïve state and even more dramatically increased ADAM10 after anti-CD40/IL4 stimulation compared C57 (Th1 prone) WT B cells. Furthermore, ADAM17 and TNF are reduced in allergic patients and Th2 prone mouse strains (Balb/c and A/J) compared to Th1 prone controls. To further understand this regulation, ADAM17 and TNF were studied in C57Bl/6 and Balb/c mice deficient in ADAM10. C57-ADAM10^B-/- were more adept at increasing ADAM17 levels and thus TNF cleavage resulting in excess follicular TNF levels and abnormal secondary lymphoid tissue architecture not noted in Balb-ADAM10^B-/-. Moreover, the level of B cell ADAM10 as well as Th context is critical for determining IgE production potential. Using a murine house dust mite airway hypersensitivity model, we describe that high B cell ADAM10 level in a Th2 context (Balb/c WT) is optimal for disease induction including bronchoconstriction, goblet cell metaplasia, mucus, inflammatory cellular infiltration, and IgE production. Balb/c mice deficient in B cell ADAM10 have attenuated lung and airway symptoms compared to Balb WT and are actually most similar to C57 WT (Th1 prone). C57-ADAM10^B-/- have even further reduced symptomology. Taken together, it is critical to consider both innate B cell levels of ADAM10 and ADAM17 as well as Th context when determining host susceptibility to allergic disease. High B cell ADAM10 and low ADAM17 levels would help diagnostically in predicting Th2 disease susceptibility; and, we provide support for the use ADAM10 inhibitors in treating Th2 disease.

A Novel B-2 Suppressor Cell Regulating Susceptibility/Resistance of Mice toToxoplasma gondiiInfection

Irradiation treatment enhanced resistance of C57BL/6, but not BALB/c against Toxoplasma gondii infection. Six Gy-irradiated (IR) C57BL/6 recipients of B-2 cells from T. gondii-infected C57BL/6 died after infection. B-2 suppressor cells from infected C57BL/6 enhanced production of IL-4 and IL-10 in peritoneal exudate cells (PECs), and down-regulated NO release in peritoneal macrophages after infection. On the other hand, B-2 suppressor cells were not detected in a strain, BALB/c, resistant against infection. These data indicated that irradiation-sensitive B-2 cells regulated susceptibility/resistance in mice against T. gondii infection.

Kinetics study and characterisation of target excreted/secreted antigens of immunoglobulin G, M, A and E antibodies from mice infected with different strains of Toxoplasma gondii

A kinetics study and characterisation of target excreted/secreted antigens of immunoglobulin (Ig) G, M, A and E antibodies were realised by Western blotting with immune sera of mice inoculated with three strains of Toxoplasma gondii: RH, C56 and S3. IgG antibodies of the immune sera recognised the major proteins of the three excreted/secreted antigen preparations with molecular masses of 30, 45, 63 and 77 kDa. IgM antibodies recognised proteins revealed by IgG antibodies but with variable intensities; some proteins were revealed during a short period. IgA antibodies did not recognise the 35-kDa antigen or the antigens inferior to 28 kDa. The RH excreted/secreted antigens were revealed with the highest intensity. The IgE antibodies were briefly detected in trace amounts during period from the 20th to the 35th day. The RH strain with its excreted/secreted antigens had the best antigenicity and is a good model for immunoprotection studies.

Isotypic profiles of antibody responses to Toxoplasma gondii infection in rats and mice: kinetic study and characterization of target antigens of immunoglobulin A antibodies

The antibody responses to Toxoplasma gondii were investigated in rat and mouse experimental models. The immunoglobulin A (IgA) antibody response was of particular interest because acquisition of Toxoplasma gondii is usually by the oral route. The rat model was used because the natural resistance of rats to the parasite is similar to the natural resistance exhibited by adult humans. There was an early and simultaneous rise in IgA and IgM antibody responses. The IgA antibody response was maximal around day 40. IgA antibodies from Fischer rats were mainly directed against soluble and membrane antigens of 28.5, 29, 30, 35, and 38 kilodaltons (kDa). In mice, however, a major antigen of 29 kDa was recognized by IgA antibodies. Moreover, in orally infected rats, an intense IgE antibody response against the major surface antigen, P30, was observed. An IgA antibody response was also observed in rats and mice immunized with Toxoplasma excreted-secreted antigens, even without adjuvant. This response was mainly directed against 28.5- and 34-kDa antigens in rats. Serum IgA from infected rats tested against the excreted-secreted antigens bound to 28.5- 34-, and 39-kDa antigens, whereas sera from infected mice recognized only the 34-kDa antigen.