Synthesis of tritiated tuftsin and macrophage inhibitory tripeptide via acetylenic intermediates

Acetylenic analogues of tuftsin (Thr-Dah-Pro-Arg) and of a macrophage inhibitory tripeptide (Thr-Dah-Pro) have been synthesized by conventional procedures in solution (Dah = 2,6-diamino-4-hexynoic acid). These acetylenic derivatives are intermediates for the preparation of structurally unmodified, tritiated peptides. Catalytic tritiation of Thr-Dah-Pro-Arg and of Thr-Dah-Pro has afforded the radioactive tetra- and tripeptides with specific activities of 11.4 Ci/mmol and 37 Ci/mmol, respectively.     

Inhibition of in vitro adherence of antibody-coated red cells to monocytes by the dialyzable leukocyte extract

The red cell-monocyte assay (RMA), which has been used to evaluate the clinical significance of red cell (RBC) antibodies, was employed to test the effect of the dialyzable leukocyte extract (DLE) on in vitro adherence to monocytes of human RBCs coated with alloantibodies or autoantibodies. The total association index (TAI) of the RMA, expressing the number of RBCs adhering to or phagocytosed by 100 monocytes, indicated a potent inhibitory activity of DLE in the test system. TAI values of 100.4 +/- 20.1 (mean +/- SD) in the control sample, consisting of RBCs coated in vitro with anti-D, dropped to 4.0 +/- 2.1 when DLE was present in the assay medium at a concentration of 0.5 U per mL. Similar results were obtained with RBCs coated with IgG antibodies in vivo. The inhibition was dose dependent and was associated with a thermolabile component of DLE. This study establishes that DLE can modulate monocyte function by inhibiting the recognition of IgG sensitized red cells.     

Keratinocyte Growth Factor Ameliorates Dextran Sodium Sulfate Colitis in Mice

Keratinocyte growth factor (KGF) is emerging asan important mediator of mucosal defense and repair inthe colon. The aim of the present study was to evaluateand further characterize the effects of exogenous KGF administration utilizing the dextran sodiumsulfate (DSS) model of colitis in mice. Colitis wasinduced via oral administration of DSS (5 g/100 ml) toBalb/c mice for eight days. Intraperitonealadministration of KGF (5 mg/kg, once daily) or vehicle (VEH)was initiated 1 hr prior to the induction of the colitis(N = 10, each group). Mucosal injury of the entire colonwas histologically assessed and graded. An approximately fourfold reduction in the cryptdamage score was noted in the KGF group when compared tocontrols (VEH) (2.8 ± 1.03 and 11.4 ±0.78, respectively). The significant reduction ofmucosal injury in KGF treated mice confirms that KGF isa key mediator maintaining the integrity of the colonicmucosa.