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Distinct kinetics of memory B-cell and plasma-cell responses in peripheral blood following a blood-stage Plasmodium chabaudi infection in mice.

Nduati EW, Ng DH, Ndungu FM, Gardner P, Urban BC, Langhorne J - PLoS ONE (2010)

Bottom Line: We detected memory B cells, defined as isotype-switched IgD(-) IgM(-) CD19(+) B cells, and low numbers of Plasmodium chabaudi Merozoite Surface Protein-1 (MSP1)-specific memory B cells, in PBMC at all time points sampled for up to 90 days following primary or secondary infection.CD138(+) plasma cells in PBMC at these times expressed CD19, B220 and MHC class II, suggesting that they were not dislodged bone-marrow long-lived plasma cells, but newly differentiated migratory plasmablasts migrating to the bone marrow; thus reflective of an ongoing or developing immune response.Studies should therefore include multiple sampling points, and at times of infection/immunisation when the B-cell phenotypes of interest are likely to be found in peripheral blood.

View Article: PubMed Central - PubMed

Affiliation: KEMRI/Wellcome Trust Collaborative Research Programme, Centre for Geographical Medicine Research Coast, Kilifi, Kenya.

ABSTRACT
B cell and plasma cell responses take place in lymphoid organs, but because of the inaccessibility of these organs, analyses of human responses are largely performed using peripheral blood mononuclear cells (PBMC). To determine whether PBMC are a useful source of memory B cells and plasma cells in malaria, and whether they reflect Plasmodium-specific B cell responses in spleen or bone marrow, we have investigated these components of the humoral response in PBMC using a model of Plasmodium chabaudi blood-stage infections in C57BL/6 mice. We detected memory B cells, defined as isotype-switched IgD(-) IgM(-) CD19(+) B cells, and low numbers of Plasmodium chabaudi Merozoite Surface Protein-1 (MSP1)-specific memory B cells, in PBMC at all time points sampled for up to 90 days following primary or secondary infection. By contrast, we only detected CD138(+) plasma cells and MSP1-specific antibody-secreting cells within a narrow time frame following primary (days 10 to 25) or secondary (day 10) infection. CD138(+) plasma cells in PBMC at these times expressed CD19, B220 and MHC class II, suggesting that they were not dislodged bone-marrow long-lived plasma cells, but newly differentiated migratory plasmablasts migrating to the bone marrow; thus reflective of an ongoing or developing immune response. Our data indicates that PBMC can be a useful source for malaria-specific memory B cells and plasma cells, but extrapolation of the results to human malaria infections suggests that timing of sampling, particularly for plasma cells, may be critical. Studies should therefore include multiple sampling points, and at times of infection/immunisation when the B-cell phenotypes of interest are likely to be found in peripheral blood.

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MSP1-specific IgG memory B cells are detectable in peripheral blood in low numbers.The frequencies of MSP1-specific IgG memory B cells were determined by in vitro cultured ELISpot assays as described in the experimental procedures. The frequencies of MSP1-specific IgG memory B cells in peripheral blood and spleen following both a primary and secondary infection are presented as memory B cells per ml of blood and per spleen respectively. The values and error bars shown are the means and the standard errors of the mean (SEM) of 5 to 7 mice.
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pone-0015007-g004: MSP1-specific IgG memory B cells are detectable in peripheral blood in low numbers.The frequencies of MSP1-specific IgG memory B cells were determined by in vitro cultured ELISpot assays as described in the experimental procedures. The frequencies of MSP1-specific IgG memory B cells in peripheral blood and spleen following both a primary and secondary infection are presented as memory B cells per ml of blood and per spleen respectively. The values and error bars shown are the means and the standard errors of the mean (SEM) of 5 to 7 mice.

Mentions: The persistently low frequency of memory B cells in peripheral blood detected by flow cytometry suggested that the frequency of detectable malaria-specific B cells might be very low. We used an ELISpot assay to detect MSP1-specific IgG MBC during primary and secondary infection (Figure 4). In line with the low frequency of isotype-switched MBC, the frequency of MSP1-specific IgG MBC in PBMC as determined by ELISpot was also very low but consistent from day 10 of a primary infection onwards (Figure 4, top left graph, ∼12 MSP1-specific IgG MBC per ml of blood). This was markedly lower than the numbers seen per spleen, which, as described previously [38], peaked at day 10 of infection (figure 4, bottom left graph, approximately 1500 MSP1-specific IgG MBC (per spleen), then contracted (approximately 500 per spleen) and persisted for up to day 90. Thus MBC in peripheral blood can be detected in low numbers after peak parasitaemia, but do not reflect the kinetics of MBC in the spleen.


Distinct kinetics of memory B-cell and plasma-cell responses in peripheral blood following a blood-stage Plasmodium chabaudi infection in mice.

Nduati EW, Ng DH, Ndungu FM, Gardner P, Urban BC, Langhorne J - PLoS ONE (2010)

MSP1-specific IgG memory B cells are detectable in peripheral blood in low numbers.The frequencies of MSP1-specific IgG memory B cells were determined by in vitro cultured ELISpot assays as described in the experimental procedures. The frequencies of MSP1-specific IgG memory B cells in peripheral blood and spleen following both a primary and secondary infection are presented as memory B cells per ml of blood and per spleen respectively. The values and error bars shown are the means and the standard errors of the mean (SEM) of 5 to 7 mice.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2990717&req=5

pone-0015007-g004: MSP1-specific IgG memory B cells are detectable in peripheral blood in low numbers.The frequencies of MSP1-specific IgG memory B cells were determined by in vitro cultured ELISpot assays as described in the experimental procedures. The frequencies of MSP1-specific IgG memory B cells in peripheral blood and spleen following both a primary and secondary infection are presented as memory B cells per ml of blood and per spleen respectively. The values and error bars shown are the means and the standard errors of the mean (SEM) of 5 to 7 mice.
Mentions: The persistently low frequency of memory B cells in peripheral blood detected by flow cytometry suggested that the frequency of detectable malaria-specific B cells might be very low. We used an ELISpot assay to detect MSP1-specific IgG MBC during primary and secondary infection (Figure 4). In line with the low frequency of isotype-switched MBC, the frequency of MSP1-specific IgG MBC in PBMC as determined by ELISpot was also very low but consistent from day 10 of a primary infection onwards (Figure 4, top left graph, ∼12 MSP1-specific IgG MBC per ml of blood). This was markedly lower than the numbers seen per spleen, which, as described previously [38], peaked at day 10 of infection (figure 4, bottom left graph, approximately 1500 MSP1-specific IgG MBC (per spleen), then contracted (approximately 500 per spleen) and persisted for up to day 90. Thus MBC in peripheral blood can be detected in low numbers after peak parasitaemia, but do not reflect the kinetics of MBC in the spleen.

Bottom Line: We detected memory B cells, defined as isotype-switched IgD(-) IgM(-) CD19(+) B cells, and low numbers of Plasmodium chabaudi Merozoite Surface Protein-1 (MSP1)-specific memory B cells, in PBMC at all time points sampled for up to 90 days following primary or secondary infection.CD138(+) plasma cells in PBMC at these times expressed CD19, B220 and MHC class II, suggesting that they were not dislodged bone-marrow long-lived plasma cells, but newly differentiated migratory plasmablasts migrating to the bone marrow; thus reflective of an ongoing or developing immune response.Studies should therefore include multiple sampling points, and at times of infection/immunisation when the B-cell phenotypes of interest are likely to be found in peripheral blood.

View Article: PubMed Central - PubMed

Affiliation: KEMRI/Wellcome Trust Collaborative Research Programme, Centre for Geographical Medicine Research Coast, Kilifi, Kenya.

ABSTRACT
B cell and plasma cell responses take place in lymphoid organs, but because of the inaccessibility of these organs, analyses of human responses are largely performed using peripheral blood mononuclear cells (PBMC). To determine whether PBMC are a useful source of memory B cells and plasma cells in malaria, and whether they reflect Plasmodium-specific B cell responses in spleen or bone marrow, we have investigated these components of the humoral response in PBMC using a model of Plasmodium chabaudi blood-stage infections in C57BL/6 mice. We detected memory B cells, defined as isotype-switched IgD(-) IgM(-) CD19(+) B cells, and low numbers of Plasmodium chabaudi Merozoite Surface Protein-1 (MSP1)-specific memory B cells, in PBMC at all time points sampled for up to 90 days following primary or secondary infection. By contrast, we only detected CD138(+) plasma cells and MSP1-specific antibody-secreting cells within a narrow time frame following primary (days 10 to 25) or secondary (day 10) infection. CD138(+) plasma cells in PBMC at these times expressed CD19, B220 and MHC class II, suggesting that they were not dislodged bone-marrow long-lived plasma cells, but newly differentiated migratory plasmablasts migrating to the bone marrow; thus reflective of an ongoing or developing immune response. Our data indicates that PBMC can be a useful source for malaria-specific memory B cells and plasma cells, but extrapolation of the results to human malaria infections suggests that timing of sampling, particularly for plasma cells, may be critical. Studies should therefore include multiple sampling points, and at times of infection/immunisation when the B-cell phenotypes of interest are likely to be found in peripheral blood.

Show MeSH
Related in: MedlinePlus