Pregnancy and humoral immune response in mice chronically infected by Trypanosoma cruzi

Abstract

The effect of pregnancy on the humoral immune response induced by Trypanosoma cruzi was studied in groups of chronically infected and pregnant mice (IP) or chronically infected and nonpregnant mice (INP) of strain BALB/c. Groups of noninfected and nonpregnant mice (NINP) or noninfected and pregnant mice (NIP) served as controls. The pregnant mice were killed on day 17 of pregnancy. Anti-T. cruzi immunoglobulin G (IgG) and IgM antibodies, detected by immunofluorescence or enzyme-linked immunosorbent assay or both, underwent a pregnancy-associated decrease of 20 to 40%, whereas complement-mediated lytic antibodies were unaffected by pregnancy. Immunoblotting analysis indicated identical specificities of the anti-T. cruzi antibodies in IP and INP groups. The levels of all the immunoglobulin isotypes (particularly IgG2a and IgG3), circulating immune complexes, rheumatoid-like factor, and anti-DNA antibodies were considerably increased during chronic infection (NINP versus INP), which could be related to the high degree of polyclonal B-cell activation occurring in T. cruzi infection. However, pregnancy significantly decreased (by 20 to 60%) such parameters. IgG levels were particularly affected (by 40 to 60%), and the decreases could be ordered as follows: IgG3 > IgG2a > IgGI > IgG2b for IP versus INP. Comparisons between the noninfected groups indicated differences only in IgG levels. These results indicate the following. (i) The specific humoral anti-T. cruzi immune response is weakly affected by pregnancy, which is not sufficient to modify the course of the mother's infection. (ii) Pregnancy does not modify the expression of the anti-T. cruzi antibody repertory. (iii) Pregnancy reduces the polyclonal B-cell activation, particularly the levels of the IgG isotypes undergoing the greatest activation.

Trypanosoma cruzi infection in mice induces a polyisotypic hypergammaglobulinaemia and parasite‐specific response involving high lgG2a concentrations and highly avid lgG1 antibodies

“…So, probably, the latter is not the only mechanism inducing the autoimmune disorders occurring late in this stage of infection (Spinella et al 1992). Total IgG2a, (in agreement with previous reports (Carlier et al 1987a, Spinella et al 1992, IgM and IgE levels were particularly raised, in comparison to other isotypes. This set of changes in the isotypic profile of total immunoglobulins can be considered as characteristic of T. cruzi infection, since infections with viruses or other parasites produce different patterns of hypergammaglobulinaemia.…”

“…Our data indicate that the dominance of IgG2a antibody titres over the other isotypes, previously reported in various strains of mice (Carlier et al 1987a, Rowland et al 1992, Spinella et al 1992, Powell & Wassom 1993, is due to higher plasma Concentrations. Indeed, IgG2a concentrations were two to 67 times higher than that of the other IgG, IgA or IgM antibody isotypes, and corresponded to about 50% to 70% of all available T. cruzi-specific antibodies.…”

The Endogenous Balance of Soluble Tumor Necrosis Factor Receptors and Tumor Necrosis Factor Modulates Cachexia and Mortality in Mice Acutely Infected withTrypanosoma cruzi

“…inoculation of 100 blood trypomastigotes of the Tehuantepec strain of T. cruzi maintained in our laboratory. Parasitemia was determined in tail blood every 3 to 4 days, as previously described (11). Mortality and weight of mice were regularly recorded.…”

Susceptibility to Trypanosoma cruzi is modified by a previous non‐related infection

“…Sex-and age-matched uninfected mice, and as well as mice infected only with T. cruzi were used as controls. The level of T. cruzi parasitaemia was monitored at several days after inoculation by counting the number of parasites in 5 ml of blood drawn from the tail vein; data are reported as the number of parasites per ml (Carlier et al 1987;Cardillo et al 1996).…”