Figure 2. LFA-1 Maintains Tfh Cells within the GC Niche by Limiting Apoptosis.

(A–D) 4get/KN2 mice were infected with Hp and administered anti-αL, anti-β2, or Rat IgG blocking antibodies i.p. at 2 weeks post-infection. mLNs were harvested 24 hr after antibody treatment and assessed by flow cytometry or confocal microscopy. (A) The number of GFP⁺huCD2⁻, GFP⁺huCD2⁺, and CXCR5⁺PD-1⁺ CD4⁺B220⁻mLN cells. (B) Immunofluorescent images of mLN sections stained with GL7 (green), huCD2 (red), and CD35 (blue). (C) The number of B220⁺ GL7⁺IgD⁻mLN cells 24 hr after anti-αL treatment. (D) Representative histograms of CD69 expression of the GFP⁺huCD2⁻and GFP⁺huCD2⁺ CD4⁺ mLN cell populations from rat IgG (unshaded histogram) or anti-αL (shaded histogram) treated 4get/KN2 mice 24 hr after treatment. Inset numbers represent MFI.

(E) The number of GFP⁻CD62L⁺, GFP⁺huCD2⁻, and GFP⁺huCD2⁺ CD4⁺ mLN cells from infected 4get/KN2 mice 24 hr after treatment with FTY720, anti-αL, or both. Rat IgG was used as a control.

(F) Total cell counts of GFP⁺huCD2⁺ CD4⁺ mLN cells at the indicated time points post-administration of αL antibody to 2 week Hp-infected 4get/KN2 mice.

(G) Expression of S1p1 mRNA in GFP⁺huCD2⁻and GFP⁺huCD2⁺ mLN CD4⁺ T cell populations sorted from 2 week Hp infected 4get/KN2 mice relative to the GFP⁻huCD2⁻population.

(H) Representative contour plots gated on CD4⁺B220⁻cells from the mesenteric lymph node and mesenteric efferent lymphoid vessels of 2 week Hp infected 4get/KN2 mice. Numbers represent frequency of the gated subset from the total CD4⁺ population. (I) Frequency of huCD2⁺ cells from the total GFP⁺CD4⁺ cell population from the mesenteric efferent lymph at various time points following αL integrin blockade of 2 week Hp-infected 4get/KN2 mice.

(J) Fas expression (MFI) by Tfh (CD4⁺B220⁻CD62L⁻CD44⁺CXCR5⁺huCD2⁺) and non-Tfh effector cells (CD4⁺B220⁻CD62L⁻CD44⁺CXCR5⁻huCD2⁻) from the mLNs of 4get/KN2 mice 8 hr post αL blockade.

(K) Frequency of active caspase-3⁺ Tfh (CD4⁺B220⁻CD62L⁻CD44⁺CXCR5⁺huCD2⁺ or CD4⁺B220⁻CD62L⁻CD44⁺CXCR5⁺PD-1⁺) and non-Tfh effector cells (CD4⁺B220⁻CD62L⁻CD44⁺CXCR5⁻huCD2⁻or CD4⁺B220⁻CD62L⁻CD44⁺CXCR5⁻PD⁻1⁻) from the mLNs of 4get/KN2 mice 8 hr post αL blockade. Dots in graphs represent individual mice.

(A)–(J) are representative of at least two independent experiments and (K) shows representative data compiled from four independent experiments. ***p < 0.001, **p < 0.01, and *p < 0.05. Error bars, SD ns, not significant. See also Figure S1.