Lymphatic pump treatment augments lymphatic flux of lymphocytes in rats

Background: Lymphatic pump techniques (LPT) are used by osteopathic practitioners for the treatment of edema and infection; however, the mechanisms by which LPT enhances the lymphatic and immune systems are poorly understood. Methods and Results: To measure the effect of LPT on the rat, the cisterna chyli (CC) of 10 rats were cannulated and lymph was collected during 4min of 1) pre-LPT baseline, 2) 4 min LPT, and 3) 10min post-LPT recovery. LPT increased significantly (p<0.05) lymph flow from a baseline of 24±5μl/min to 89±30μl/min. The baseline CC lymphocyte flux was 0.65±0. 21×10⁶ lymphocytes/min, and LPT increased CC lymphocyte flux to 6.10±0.99×10⁶ lymphocytes/min (p<0.01). LPT had no preferential effect on any lymphocyte population, since total lymphocytes, CD4+ T cells, CD8+ T cells, and B cell numbers were similarly increased. To determine if LPT mobilized gut-associated lymphocytes into the CC lymph, gut-associated lymphocytes in the CC lymph were identified by staining CC lymphocytes for the gut homing receptor integrin α4β7. LPT significantly increased (p<0.01) the flux of α4β7 positive CC lymphocytes from a baseline of 0.70±0.03×10⁵ lymphocytes/min to 6.50±0. 10×10⁵ lymphocytes/min during LPT. Finally, lymphocyte flux during recovery was similar to baseline, indicating the effects of LPT are transient. Conclusions: Collectively, these results suggest that LPT may enhance immune surveillance by increasing the numbers of lymphocytes released in to lymphatic circulation, especially from the gut associated lymphoid tissue. The rat provides a useful model to further investigate the effect of LPT on the lymphatic and immune systems.