FIG 1.

B cells are present in the lungs and outnumber DCs. A and B, BALB/c mice were sensitized intranasally with HDM or treated with PBS as a control on days 0, 7, 8, 9, 10, and 11 and analyzed on day 14. Representative fluorescence-activated cell sorting (FACS) plots of B cells among total lung CD45⁺ cells (Fig 1, A) and total numbers of Bcells (CD45⁺CD19⁺B220⁺) and DCs (CD45⁺CD11c⁺Siglec-F⁻) in lungs(mean ± SEM, n = 4 mice per group; Fig 1, B). C and D, Representative FACS plots of B-1 cells (CD19^hiCD43⁺) among total B cells (CD45⁺CD19⁺B220⁺) in blood, spleen, and lungs of a naive mouse (Fig 1, C) and cumulative data of percentage (mean ± SEM) of B-1 and B-2 cells from 8 mice (Fig 1, D). E and F, Representative FACS plots of IgM/IgD staining of lung B cells from PBS- or HDM-treated mice (Fig 1, E) and cumulative data (mean ± SEM) from 7 PBS-treated and 13 HDM-treated animals (Fig 1, F). IgM⁻IgD⁻ B cells consisted mainly of IgG⁺ cells (around 73% in the PBS group and 78% in the HDM group). Additionally, around 19% of IgM⁻IgD⁻ B cells in both groups were IgA⁺¹ B cells. We found virtually no IgE⁺ B cells at steady state or on HDM immunization, whereas IgG₁⁺ B cells were present at steady state and increased in frequency on allergic inflammation (9% and 22%, respectively). G and H, Surface CXCR5 expression on B cells isolated from the indicated organs of naive mice. Representative FACS plot (Fig 1, G) and cumulative data (mean ± SEM) from 8 mice (Fig 1, H) are shown. Data are representative of at least 3 independent experiments. *P < .05 and ****P < .0001.