Presenting Author: Carlos Henrique D. Barbosa
, Postdoc at Rosalind Franklin Univ. of Med. and Sci.
Abstract:
Francisella tularensis (Ft), a Gram-negative bacterium, posesses atypical LPS that does not activate TLR4 and is considered a type 2 T-independent antigen (TI-2 Ag). Our group has recently shown that immunization with Ft-LPS elicits the production of protective Ft-LPS-specific IgM (IgMFt) by B1 cells independently of MyD88, in a mechanism that is dependent of the IL-25-ILC2-IL-5 axis. Immunization, but not infection, generates peritoneum-resident memory B1 cells that differentiates into IgMFt plasmacells upon secondary challenge but does not boost the production of IgMFt.
TI antigens were believed to be unable to generate memory response or long-lived plasma cells. This view is being challenged by several studies. This work aims to elucidate the mechanisms driving the class switch and memory response of B1 cells to Ft-LPS.
Here we show that peritoneal memory B1 cells transferred into Rag-/- mice produce higher amounts of IgM compared to naïve B1 cells. Moreover, the transferred naïve B1 cells did not class switch to IgG3/IgG2b upon immunization, suggesting involvement of FDCs and/or T cells. The presence of IgGFt inhibited the IgMFt response. Complement depletion in WT mice also inhibited class switch to IgGFt but did not affect IgMFt production and resulted in better boost effect. Our results might shed light on new strategies to improve vaccination against TI-2 Ags and on involvement of germinal center and complement proteins for the activation of B1 cells
Regulation of B1 cells response to Francisella tularensis LPS, a type-2 T-independent antigen
Category
Poster and Podium (Block Symposium)
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Date: May 4 Presentation Time: 11:30 AM to 12:45 PM Room: Exhibit Hall F1