Back to 2014 Annual Meeting Abstracts

BACKGROUND: Lymphedema is a common condition occurring in as many as 1 in 3 women who undergo lymphadenectomy for breast cancer treatment. One of the most significant morbidities for these patients is recurrent infections and impaired immunity in the lymphedematous limb necessitating aggressive preventative precautions and, in some cases, prophylactic antibiotics. While microsurgical lymph node transfers (LNT) have been shown to improve lymphatic drainage, previous studies have not determined how these procedures impact immune responses. Therefore, the purpose of these experiments was to use a mouse model of lymphedema and LNT to analyze the potential for LNT to restore immunologic responses.
METHODS: We developed a mouse in which lymphatic vessels could be ablated using diphtheria toxin (DT) thereby enabling us to create localized limb lymphedema by simply injecting the limb with a small dose of DT. All animals were injected with DT in the right forepaw to ablate lymphatics and 1 week later underwent axillary lymph node dissection (ALND; n=12). Experimental animals were transplanted with a normal lymph node and perilymphatic fat from a healthy donor (n=6); control animals had ALND alone (n=6). We also analyzed normal responses in sham-operated animals (i.e. no DT and axillary incision without ALND). We then analyzed the potential for restoration of B cell (antibody) responses by immunizing the animals 3 weeks postop with ovalbumin (OVA) injection in the right forepaw. In addition, we analyzed the ability of antigen presenting cells (dendritic cells) to migrate out of the skin/subcutaneous tissues. Finally, we measured lymph node uptake using 99mTc and near-infrared imaging (NIR) using indocyanine green (ICG).
RESULTS: Ablation of lymphatics with DT and ALND resulted in significant (2-fold) increase in forepaw diameter at all time points (weeks 1-3) examined (P<0.01). Animals treated with LNT had significant reductions in forepaw diameter, and more importantly, had greater serum anti-OVA antibody levels than controls (P<0.01). However, the potential to mount antibody responses was still lower than sham-operated controls. This finding was corroborated by increased migration of skin dendritic cells in LNT treated animals, although the total number of migrated cells was far lower than sham-operated controls. LNT increased lymph node drainage (P<0.01) and newly formed lymphatic vessels could easily be seen using ICG and NIR. Interestingly, LNT appeared to increase lymphangiogenesis significantly as compared with controls as analyzed by ICG.
CONCLUSIONS: Our mouse model of non-invasive lymphatic ablation enables us to create a new model of lymphedema in mice. Using this model we have shown that LNT increases lymphangiogenesis, promotes drainage of interstitial fluid, improves antibody responses, and increases migration of antigen presenting cells from the skin. However, LNT does not completely restore immune responses (at least in the early postoperative period) suggesting that patients who are treated with this approach should continue infectious precautions.