FIGURE 3

Oral immunization of L-Sel^-/- mice with CT results in enhanced IgA AFC responses in NP 42 days post-primary immunization and supported by increases in NALT and HNLN IgA AFCs. L-Sel^-/- and L-Sel^+/+ mice were orally immunized, as previously described, and on day 42, total lymphocytes from (a, b) NP and iLP and (c, d) NALT, HNLN, and PP were collected and assayed for anti-CT-B and total (a, c) IgA and (b, d) IgG AFC responses. Each L-Sel^-/- HNLN was combined and assessed for anti-CT-B activity. CT-B-specific IgA AFC responses were elevated in L-Sel^-/- mice when compared to L-Sel^+/+ mice. IgA and IgG iLP CT-B-specific AFC responses were not significantly different between L-Sel^+/+ and L-Sel^-/- mice; however, dramatic increases in L-Sel^-/- NALT and HNLN CT-B-specific IgA and IgG AFC responses were observed when compared to L-Sel^+/+ mice. Total IgA and IgG AFCs in L-Sel^-/- HNLN and total IgG AFCs in L-Sel^-/- NALT were also elevated when compared to L-Sel^+/+ mice. Depicted are the mean AFC responses of three experiments s.e.m. per tissue, and statistical differences between L-Sel^-/- and L-Sel^+/+ mice were determined: *P<0.001; **P0.014; ***P=0.025. AFC, antibody-forming cell; CT, cholera toxin; HNLN, head and neck lymph node; Ig, immunoglobulin; iLP, intestinal lamina propria; L-Sel, L-selectin; NALT, nasal-associated lymphoid tissue; NP, nasal passage; PP, Peyer's patch; PRLN, parotid gland lymph node; SMLN, submaxillary gland lymph node.