FIGURE 5

Effector CT-B-specific B cells were mostly L-Sel^low/₇ ^low in the iLP and NP at 42 days post-primary immunization. Cell-sorting experiments were conducted sorting (a, b) iLP and (c, d) NP lymphocytes for ₇ vs. ₇ ^high and _E expression and assessed by CT-B-specific (left panel) and total (right panel) (a, c) IgA and (b, d) IgG ELISPOT. No ₇ ^high B cells were found in either L-Sel^+/+ or L-Sel^-/- NP; all the iLP ₇ ^high B cells were _E7 ⁺, not ₄₇ ^high, and the ₇ ^low B cells were all L-Sel^low/₇ ^low. The majority of the CT-B-specific iLP IgA AFCs were ₇ ^low. For both L-Sel^+/+ and L-Sel^-/- mice, the L-Sel^low/₇ ^low B-cell subset contained all of the NP IgA anti-CT-B activity, and for L-Sel^-/- mice, _E7 ⁺ B cells contained the IgG anti-CT-B and the total IgG AFCs. Results depict the mean of three experiments s.e.m., and statistical differences between ₇ ^low and _E7 ⁺ B cells were determined: *P0.002; **P0.008; ***P<0.026; ****P<0.05. AFC, antibody-forming cell; CT, cholera toxin; ELISPOT, enzyme-linked immunosorbent spot; Ig, immunoglobulin; iLP, intestinal lamina propria; L-Sel, L-selectin; NALT, nasal-associated lymphoid tissue; NP, nasal passage.