Stimulation of neuronal activity restricts antigen flow. (A, B) Electric stimulation of the nerves to the popliteal and sciatic lymph node restricts KLH-800CW flow to the sciatic lymph nodes (sham, 114.1 ± 16.17, n = 5 versus electrically stimulated, 56.76 ± 14.38, n = 5, p < .05 by t test). (A) Images are representative. (B) Antigen signal in the sciatic lymph node in individual animals is shown here. (C, D) A noninvasive magnetic field was applied to the hind legs of naïve mice to induce nerve activity, followed by injection of KLH-800CW. In magnetically stimulated animals, lower levels of antigen were observed in the sciatic lymph nodes (sham, 55.99 ± 4.993, n = 10 versus magnetically stimulated, 30.87 ± 4.169, n = 12, p < .001 by t test). (C) Images are representative; triangles indicate popliteal lymph nodes and stars represent sciatic lymph nodes. (D) Antigen signal in the sciatic lymph node in individual animals is shown here.