Vascular clearance of embolic tumor cells and colloidal carbon and the levels of serum lysozyme following muramyl dipeptide administration.

Various doses of coded samples of the parent muramyl dipeptide entity and eight synthetic analogues were injected intravenously into C57BL/6J mice, and the extent of clearance of intravenously injected 5-[125I]iodo-2-deoxyuridine (125I-dUrd) radioactively labeled B16 tumor cells from the lung was measured 3 days later. The results of between one and four experiments with each compound demonstrated that five compounds, including the parent compound, produced dose-dependent increases in the loss of tumor cells from the lung. The same five compounds also caused an increase in the clearance of intravascular carbon clearance. Monitoring of serum lysozyme levels revealed no significant increases compared to controls at doses of up to 1 mg/mouse following muramyl dipeptide (MDP) administration i.v., i.p. or s.c. at any time up to 30 days after administration. Increased pulmonary tumor cell clearance did not occur after s.c. MDP administration and peaked 3 days after i.p. or i.v. MDP, reaching near normal levels by Day 7.