Inhibition of lung tumor colonization by leech salivary gland extracts from Haementeria ghilianii.

Salivary gland extract from the South American leech Haementeria ghilianii, administered i.v. on the same day as the i.v. inoculation of T241 sarcoma cells, completely suppresses colonization of the mediastinal lymph nodes and markedly reduces the number and size of lung tumor colonies produced by this tumor. Additional studies indicate that the extract contains various types of proteinase inhibitors and has the capacity to inhibit clotting and platelet aggregation by tumor material and collagen. Although not yet proved by direct evidence, these activities may be involved in the inhibitory effect of lung tumor colonization by the leech extract.