FIG. 3.

Immunohistochemistry and confocal laser scanning imaging: a and b, control (a, nasopharynx; b, middle ear); c, d, e, and f; P6+CT-immunized (c, nasopharynx; d and e, middle ear; f, confocal laser scanning imaging of the middle ear). Magnifications: a, b, c, and d, × 100; e and f, × 400. Large numbers of IgA-positive cells are shown in the MEM and the nasopharynx of P6+CT-immunized mice. The black arrows indicate IgA-positive cells (e). Confocal laser scanning imaging shows P6-specific IgA-producing cells in the middle ear of P6+CT-immunized mice. The white arrows indicate P6-specific IgA-producing cells (f).