Lymphatic pump treatment enhances pulmonary immunity and protects against solid tumor formation in the rat lung. (161.14)

Abstract

Abstract Lymphatic pump treatments (LPT) are used by osteopathic physicians to treat edema and infection. In animals, LPT increases lymph flow and leukocyte numbers, which may enhance protection against infection and cancer. To determine if LPT would enhance anti-tumor immunity and reduce tumor formation in the lungs, F344 rats were injected intravenously with MADB106. Rats received no treatment (control), 4 min of light touch under anesthesia (sham), or 4 min of LPT under anesthesia, for 7 days. At day 8, tissues were measured for tumors and leukocyte numbers/activities. Serum was measured for vascular endothelial growth factor C (VEGF-C). LPT reduced solid tumors and increased B cell, CD4+ T cell, CD8+ T cell, NK cell and macrophage numbers in the lungs. In addition, Leukocytes isolated from the lungs of LPT rats secreted more IL-2, IL-10 and IFN-γ but did not enhance tumor lysis in vitro. Previously we demonstrated LPT mobilizes gut-derived lymphocytes into lymphatic circulation; therefore, we stained pulmonary lymphocytes for the gut marker α4β7. LPT increased α4+β7+ leukocytes in the lungs, suggesting LPT mobilizes gut-derived leukocytes into the lungs. Finally, there were no differences in the levels of VEGF-C between treatment groups, suggesting that LPT does not promote lymphangiogenesis in this model. Our data suggests LPT inhibits pulmonary tumor formation by enhancing the numbers of leukocytes with anti-tumor activities that migrate into the lungs.