Fig. 1

Lung-infiltrating B cells develop a GC-like phenotype despite the absence of iBALT structures. A Mouse model for the analysis of antigen-specific T and B cells in the lung and lung-draining lymph nodes. T cells from Smarta T-cell receptor transgenic mice (recognizing LCMV GP1 [43]) and B cells from B1-8i BCR knock-in mice (recognizing nitrophenol (NP) [45]) are adoptively transferred into C57BL/6 mice. Recipients are then immunized repeatedly with a cognate antigen (Smarta peptide and NIP coupled to mouse serum albumin as a nonimmunogenic carrier) and LPS as an adjuvant. After development of full lung inflammation, antigen-specific T and B cells (identified by the congenic markers Thy-1.1 and CD45.1, Supplementary Fig. S1) from lung tissue, airways (bronchoalveolar lavage (BAL)) and the lung-draining lymph node (Ln) can be analyzed by flow cytometry or immunohistology. B Phenotypes of antigen-specific B cells from lymph nodes, lung tissue, and airways analyzed on day 17. Flow cytometry staining for plasmablasts (CD19^low CD138⁺) and GC-like B cells (CD19⁺ CD38^low GL7⁺ Bcl-6⁺). Plots are concatenated from a representative experiment (out of more than 20 experiments) with six mice; percentages represent the means ± SDs. The rainbow scale in the lower panel indicates the expression (geometric mean) of Bcl-6. C Immunohistology analysis of antigen-specific T and B cells and nuclei (DAPI, gray) in combination with IgD, FDC (CD21/35⁺), stromal cells (ER-TR7⁺), or the nuclear proliferation antigen Ki-67. The scale bars represent 50 µm. Representative data from two independent experiments with a total of 15 mice are shown