Trypanosoma cruzi infection induces a massive extrafollicular and follicular splenic B-cell response which is a high source of non-parasite-specific antibodies - PubMed (original) (raw)

Trypanosoma cruzi infection induces a massive extrafollicular and follicular splenic B-cell response which is a high source of non-parasite-specific antibodies

Daniela A Bermejo et al. Immunology. 2011 Jan.

Abstract

Acute infection with Trypanosoma cruzi, the aetiological agent of Chagas' disease, results in parasitaemia and polyclonal lymphocyte activation. It has been reported that polyclonal B-cell activation is associated with hypergammaglobulinaemia and delayed parasite-specific antibody response. In the present study we analysed the development of a B-cell response within the different microenvironments of the spleen during acute T. cruzi infection. We observed massive germinal centre (GC) and extrafollicular (EF) responses at the peak of infection. However, the EF foci were evident since day 3 post-infection (p.i.), and, early in the infection, they mainly provided IgM. The EF foci response reached its peak at 11 days p.i. and extended from the red pulp into the periarteriolar lymphatic sheath. The GCs were detected from day 8 p.i. At the peak of parasitaemia, CD138(+) B220(+) plasma cells in EF foci, red pulp and T-cell zone expressed IgM and all the IgG isotypes. Instead of the substantial B-cell response, most of the antibodies produced by splenic cells did not target the parasite, and parasite-specific IgG isotypes could be detected in sera only after 18 days p.i. We also observed that the bone marrow of infected mice presented a strong reduction in CD138(+) B220(+) cells compared with that of normal mice. Hence, in acute infection with T. cruzi, the spleen appears to be the most important lymphoid organ that lodges plasma cells and the main producer of antibodies. The development of a B-cell response during T. cruzi infection shows features that are particular to T. cruzi and other protozoan infection but different to other infections or immunization with model antigens.

PubMed Disclaimer

Figures

Figure 1

B-cell subset numbers in Trypanosoma cruzi infection. Splenic cells from normal (day 0) or _T. cruzi_-infected mice were obtained at different days post infection (p.i.). Graphs show absolute number of (a) IgM+ IgD+ B220+ cells (mature B2 cells), (b) IgM+ IgD− B220+ cells (immature and/or activated B cells) and (c) IgM− IgD− B220+ cells at different days p.i. Diamonds represent the value obtained from each mouse. The lines represent the median value in each analysed group. The statistically significant difference between normal (day 0) and infected mice is shown as * in each graph (P< 0·01). Results are representative for four individual experiments.

Figure 3

Extrafollicular (EF) foci in _Trypanosoma cruzi_-infected mice infiltrate T-cell zone Photomicrograph of serial sections from the same spleen obtained from 11-day _T. cruzi_-infected mice stained with: anti-CD138, anti-IgD and anti-CD3. (a) CD138+ EF focus stained blue and IgD+ B cells (follicular mantle) stained brown; (b) CD3+ T cells in blue and the follicular mantle in brown.

Figure 2

Germinal centres (GCs) and extrafollicular (EF) splenic B-cell responses in T. cruzi infection. (a) Semi-quantitative histological analysis of splenic B-cell response. Slides from the immunohistological analysis were assessed by two people independently as the extent of reaction in arbitrary units (zero = the level seen in non-infected mice and 6 = a maximum response). The mean score for four mice in each group at each time-point is depicted. GCs were identified as PNA+ Ki67+ areas. EF foci were defined as CD138+ PNA− Ki67−. (b) Photomicrographs of serial sections from the same spleen obtained from 32-day _Trypanosoma cruzi_-infected mice stained with: anti-Ki67 and anti-CD138 (upper photograph), anti-IgD and anti-CD3 (middle photograph) and anti-IgD and peanut agglutinin (PNA; lower photograph). The inset shows, at high power, Ki67 expression by some of the plasmacytoid cells in part of an EF focus. The sections shown are representative of four mice at this time-point. GC, germinal centre; EF, extrafollicular; TZ, T-cell zone.

Figure 4

Trypanosoma cruzi infection induces ectopic germinal centres (GC). Photomicrograph of serial sections from the same spleen obtained from 18-day _T. cruzi_-infected mice stained with: peanut agglutinin (PNA), anti-IgD and anti-Ki67. Photograph shows ectopic GC tissue in the red pulp (RP). (a) Ectopic PNA+ Ki67+ cells double stained in dark brown, (b) a PNA+ GC stained blue surrounded by follicular mantle (F) with IgD+ B cells stained brown. Elongated collections of PNA+ GC-like cells in the red pulp are indicated by arrows.

Figure 5

Immunoglobulin expression in plasma cells from extrafollicular (EF) foci, red pulp and T-cell zones. Semi-quantitative histological analysis of immunoglobulin expression in CD138+ cells. Slides from the immunohistological analysis were assessed by two people independently as the extent of reaction in arbitrary units (zero = the level seen in non-infected mice, and 6 = a maximum response) and the mean score for four mice in each group at each time-point is depicted. CD138+ IgM+ (a) or CD138+ IgG isotypes+ (b) cells were identified in EF foci, red pulp and T-cell zone by the staining with: anti-CD138, anti-IgM, anti-IgG1, anti-IgG2a, anti-IgG2b, anti-IgG3, peanut agglutinin (PNA), anti-IgD and anti-CD3. EF, extrafollicular; TZ, T-cell zone; RP, red pulp.

Figure 7

Parasite-specific antibodies in sera from _Trypanosoma cruzi_-infected mice. _T. cruzi_-specific IgM and IgG isotypes titres were determined by ELISA in sera from normal (day 0) or _T. cruzi_-infected mice at different days post-infection. Test sera were considered positive if the mean optical density value was two standard deviations above the mean value for control sera. Diamonds represent the value obtained from each mouse. The lines represent the median value in each analysed group. The significant difference between normal (day 0) and infected mice is indicated by * (P< 0·05). Results are representative for four individual experiments.

Figure 6

Immunoglobulin production by spleen cells from _Trypanosoma cruzi_-infected mice. IgM and IgG isotype concentrations, determined by ELISA, in culture supernatant of splenic cells obtained from normal (day 0) or _T. cruzi_-infected mice at different days post-infection. Diamonds represent the value obtained from each mouse. The lines represent the median value in each analysed group. The significant difference between normal (day 0) and infected mice is indicated by * (P< 0·05). Results are representative for four individual experiments.

Figure 8

Plasma cells are absent in the bone marrow of _Trypanosoma cruzi_-infected mice. Bone marrow cells were obtained from non-infected (day 0) or _T. cruzi_-infected mice (day 8 and 18) and incubated with anti-B220 and anti-CD138 and analysed by flow cytometry. Graphs show in (a) are representative plots of CD138 versus B220 with the percentages of CD138+ B220+ cells, and in (b) are the absolute number of B220+ CD138+cells on different days of infection. Diamonds represent the value obtained from each mouse. The lines represent the median value in each analysed group. The significant difference between normal (day 0) and infected mice is indicated by * (P< 0·05). Results are representative for two individual experiments.

Figure 9

Spleen of _Trypanosoma cruzi_-infected mice is the main immunoglobulin-producing lymphoid organ. Mononuclear cells from spleen, peritoneum (Per) and inguinal lymph nodes (LN) were obtained from normal (N) or 18-day _T. cruzi_-infected mice, counted in a Neubauer chamber and incubated for 30 hr at 37° in 5% CO2 without stimulus. IgG isotype concentration was determined in the culture supernatant of 2 × 106 cells/ml by ELISA. The values expressed as amount of immunoglobulins/lymphoid tissue mononuclear cells were depicted in ordinates. Diamonds represent the value obtained from each mouse. The lines represent the median value in each analysed group. The significant difference between normal (day 0) and infected mice is indicated by * (P< 0·05). Results are representative for three individual experiments.

References

1. Hotez PJ, Bottazzi ME, Franco-Paredes C, et al. The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination. PLoS Negl Trop Dis. 2008;2:e300. - PMC - PubMed
1. Minoprio P, Burlen O, Pereira P, et al. Most B cells in acute Trypanosoma cruzi infection lack parasite specificity. Scand J Immunol. 1998;28:553–61. - PubMed
1. Spinella S, Liegeard P, Hontebeyrie-Joskowicz M. Trypanosoma cruzi: predominance of IgG2a in nonspecific humoral response during experimental Chagas’ disease. Exp Parasitol. 1992;74:46–56. - PubMed
1. Kierszenbaum F, Howard JG. Mechanisms of resistance against experimental Trypanosoma cruzi infection: the importance of antibodies and antibody-forming capacity in the Biozzi high and low responder mice. J Immunol. 1976;116:1208–11. - PubMed
1. Sepulveda P, Hontebeyrie M, Liegeard P, et al. DNA-based immunization with Trypanosoma cruzi complement regulatory protein elicits complement lytic antibodies and confers protection against Trypanosoma cruzi infection. Infect Immun. 2000;68:4986–91. - PMC - PubMed

Trypanosoma cruzi infection induces a massive extrafollicular and follicular splenic B-cell response which is a high source of non-parasite-specific antibodies - PubMed (original) (raw)