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Activation of virus-specific memory B cells in the absence of T cell help.

Hebeis BJ, Klenovsek K, Rohwer P, Ritter U, Schneider A, Mach M, Winkler TH - J. Exp. Med. (2004)

Bottom Line: Antigenic stimulation 4-6 d after transfer of B cells resulted in rapid IgG production.Transfer of memory B cells into immunocompetent animals indicated that presence of helper T cells did not enhance the memory B cell response.Therefore, our results indicate that activation of virus-specific memory B cells to secrete IgG is independent of cognate or bystander T cell help.

View Article: PubMed Central - PubMed

Affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, D-91054 Erlangen, Germany.

ABSTRACT
Humoral immunity is maintained by long-lived plasma cells, constitutively secreting antibodies, and nonsecreting resting memory B cells that are rapidly reactivated upon antigen encounter. The activation requirements for resting memory B cells, particularly the role of T helper cells, are unclear. To analyze the activation of memory B cells, mice were immunized with human cytomegalovirus, a complex human herpesvirus, and tick-born encephalitis virus, and a simple flavivirus. B cell populations devoid of Ig-secreting plasma cells were adoptively transferred into T and B cell-deficient RAG-1-/- mice. Antigenic stimulation 4-6 d after transfer of B cells resulted in rapid IgG production. The response was long lasting and strictly antigen specific, excluding polyclonal B cell activation. CD4+ T cells were not involved since (a) further depletion of CD4+ T cells in the recipient mice did not alter the antibody response and (b) recipient mice contained no detectable CD4+ T cells 90 d posttransfer. Memory B cells could not be activated by a soluble viral protein without T cell help. Transfer of memory B cells into immunocompetent animals indicated that presence of helper T cells did not enhance the memory B cell response. Therefore, our results indicate that activation of virus-specific memory B cells to secrete IgG is independent of cognate or bystander T cell help.

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Localization of the IgG response in the presence of T cell help. Memory B cell preparations (5 × 106 CD19+ cells) together with primed CD4+ cells (2.5 × 106 cells), both from C57BL/6-Ly5.2 mice, were transferred into naive C57BL/6-Ly5.1 mice and challenged with HCMV-DBs 1 d after adoptive transfer. (A) 4 d after challenge, clusters of donor-derived (CD45.2 in blue), IgGhigh (red) cells were observed outside the follicles (thick arrows). B220 is stained in green. (B) 10 d after challenge, clusters of donor-derived (CD45.2, blue), IgGhigh (red) cells are still persistent (thick arrows); in addition IgG+ GCs could be observed inside the follicles (thin arrows). The cells participating in the GC reaction are CD45.2 negative. (C) A GC from day 10 after challenge is stained with peanut agglutinin (green). Donor CD45.2 cells are blue; IgG-positive cells are red. Magnification: (A and B) 50×; (C) 200×.
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fig5: Localization of the IgG response in the presence of T cell help. Memory B cell preparations (5 × 106 CD19+ cells) together with primed CD4+ cells (2.5 × 106 cells), both from C57BL/6-Ly5.2 mice, were transferred into naive C57BL/6-Ly5.1 mice and challenged with HCMV-DBs 1 d after adoptive transfer. (A) 4 d after challenge, clusters of donor-derived (CD45.2 in blue), IgGhigh (red) cells were observed outside the follicles (thick arrows). B220 is stained in green. (B) 10 d after challenge, clusters of donor-derived (CD45.2, blue), IgGhigh (red) cells are still persistent (thick arrows); in addition IgG+ GCs could be observed inside the follicles (thin arrows). The cells participating in the GC reaction are CD45.2 negative. (C) A GC from day 10 after challenge is stained with peanut agglutinin (green). Donor CD45.2 cells are blue; IgG-positive cells are red. Magnification: (A and B) 50×; (C) 200×.

Mentions: The lack of enhancement of the memory IgG response in the presence of primed T cell help suggested that virus-specific memory B cells are not participating in GC reactions upon challenge with virus. Therefore, we assessed the formation of GCs in naive C57BL/6-Ly5.1 mice after adoptive transfer of memory B cell preparations together with primed CD4+ cells, both from C57BL/6-Ly5.2 mice and after challenge with HCMV-DBs. GC reactions in the spleen were detectable at day 8–10 after challenge, with 9–14 GCs per section, whereas naive mice did not contain detectable GCs (not depicted). Donor-derived cells did not participate in any of more than 50 GCs analyzed (Fig. 5, B and C). Instead, clusters of donor-derived cells that were IgGhigh and had partially down-regulated CD45 appeared as early as 4 d after challenge outside B cell follicles and the T cell zone at the border of the white pulp to the red pulp (Fig. 5, A and B) at or close to the marginal zone.


Activation of virus-specific memory B cells in the absence of T cell help.

Hebeis BJ, Klenovsek K, Rohwer P, Ritter U, Schneider A, Mach M, Winkler TH - J. Exp. Med. (2004)

Localization of the IgG response in the presence of T cell help. Memory B cell preparations (5 × 106 CD19+ cells) together with primed CD4+ cells (2.5 × 106 cells), both from C57BL/6-Ly5.2 mice, were transferred into naive C57BL/6-Ly5.1 mice and challenged with HCMV-DBs 1 d after adoptive transfer. (A) 4 d after challenge, clusters of donor-derived (CD45.2 in blue), IgGhigh (red) cells were observed outside the follicles (thick arrows). B220 is stained in green. (B) 10 d after challenge, clusters of donor-derived (CD45.2, blue), IgGhigh (red) cells are still persistent (thick arrows); in addition IgG+ GCs could be observed inside the follicles (thin arrows). The cells participating in the GC reaction are CD45.2 negative. (C) A GC from day 10 after challenge is stained with peanut agglutinin (green). Donor CD45.2 cells are blue; IgG-positive cells are red. Magnification: (A and B) 50×; (C) 200×.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2211828&req=5

fig5: Localization of the IgG response in the presence of T cell help. Memory B cell preparations (5 × 106 CD19+ cells) together with primed CD4+ cells (2.5 × 106 cells), both from C57BL/6-Ly5.2 mice, were transferred into naive C57BL/6-Ly5.1 mice and challenged with HCMV-DBs 1 d after adoptive transfer. (A) 4 d after challenge, clusters of donor-derived (CD45.2 in blue), IgGhigh (red) cells were observed outside the follicles (thick arrows). B220 is stained in green. (B) 10 d after challenge, clusters of donor-derived (CD45.2, blue), IgGhigh (red) cells are still persistent (thick arrows); in addition IgG+ GCs could be observed inside the follicles (thin arrows). The cells participating in the GC reaction are CD45.2 negative. (C) A GC from day 10 after challenge is stained with peanut agglutinin (green). Donor CD45.2 cells are blue; IgG-positive cells are red. Magnification: (A and B) 50×; (C) 200×.
Mentions: The lack of enhancement of the memory IgG response in the presence of primed T cell help suggested that virus-specific memory B cells are not participating in GC reactions upon challenge with virus. Therefore, we assessed the formation of GCs in naive C57BL/6-Ly5.1 mice after adoptive transfer of memory B cell preparations together with primed CD4+ cells, both from C57BL/6-Ly5.2 mice and after challenge with HCMV-DBs. GC reactions in the spleen were detectable at day 8–10 after challenge, with 9–14 GCs per section, whereas naive mice did not contain detectable GCs (not depicted). Donor-derived cells did not participate in any of more than 50 GCs analyzed (Fig. 5, B and C). Instead, clusters of donor-derived cells that were IgGhigh and had partially down-regulated CD45 appeared as early as 4 d after challenge outside B cell follicles and the T cell zone at the border of the white pulp to the red pulp (Fig. 5, A and B) at or close to the marginal zone.

Bottom Line: Antigenic stimulation 4-6 d after transfer of B cells resulted in rapid IgG production.Transfer of memory B cells into immunocompetent animals indicated that presence of helper T cells did not enhance the memory B cell response.Therefore, our results indicate that activation of virus-specific memory B cells to secrete IgG is independent of cognate or bystander T cell help.

View Article: PubMed Central - PubMed

Affiliation: Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, D-91054 Erlangen, Germany.

ABSTRACT
Humoral immunity is maintained by long-lived plasma cells, constitutively secreting antibodies, and nonsecreting resting memory B cells that are rapidly reactivated upon antigen encounter. The activation requirements for resting memory B cells, particularly the role of T helper cells, are unclear. To analyze the activation of memory B cells, mice were immunized with human cytomegalovirus, a complex human herpesvirus, and tick-born encephalitis virus, and a simple flavivirus. B cell populations devoid of Ig-secreting plasma cells were adoptively transferred into T and B cell-deficient RAG-1-/- mice. Antigenic stimulation 4-6 d after transfer of B cells resulted in rapid IgG production. The response was long lasting and strictly antigen specific, excluding polyclonal B cell activation. CD4+ T cells were not involved since (a) further depletion of CD4+ T cells in the recipient mice did not alter the antibody response and (b) recipient mice contained no detectable CD4+ T cells 90 d posttransfer. Memory B cells could not be activated by a soluble viral protein without T cell help. Transfer of memory B cells into immunocompetent animals indicated that presence of helper T cells did not enhance the memory B cell response. Therefore, our results indicate that activation of virus-specific memory B cells to secrete IgG is independent of cognate or bystander T cell help.

Show MeSH
Related in: MedlinePlus