Ikuo Saiki

The adjuvant activity of synthetic N-acetylmuramyl-dipeptide: Evidence of initial target cells for the adjuvant activity

Abstract MurNAc- l -Ala- d -isoGln ( N -acetylmuramyl- l -alanyl- d -isoglutamine, MDP), a synthetic compound, acts as an adjuvant on the humoral immune response and on the T cell-mediated immune response. In this report, we attempted to directly demonstrate the initial target cells of MDP for its adjuvant activity in vitro by using cell separation procedures. It was demonstrated that MDP enhanced the immune response following direct interaction with antigen-stimulated T and B lymphocytes, but nonstimulated lymphocytes, shortly after triggering by antigen, and that there was no macrophage requirement for MDP to elicite the adjuvant action in the primary anti-SRBC PFC response in vitro . It has also been demonstrated that the adjuvant activity of MDP is due to an enhancing effect which is different from the possible mitogenic activity to spleen cells and MDP replaces neither a function of macrophages, which is substituted by 2-mercaptoethanol nor a helper function of T cells.

A new pseudo-peptide of Arg-Gly-Asp (RGD) with inhibitory effect on tumor metastasis and enzymatic degradation of extracellular matrix

A series of pseudo-peptide analogs of the Arg-Gly-Asp (RGD) sequence of fibronectin have been synthe-sized, and their anti-metastatic effects in mice and inhibitory effects on tumor cell invasion in vitro have been examined. The partially modified retro pseudo-peptide of RGD, Rrev-COCH2CO-D (FC-63), was more effective in inhibiting tumor metastasis than the original RGDS peptide. Replacement of the malonyl moiety of FC-63 with a carboxyethylene linkage (Rrev-COCH2CH2-D, FC-303 ) achieved more potent inhibition of lung metastasis of melanoma cells than FC-63. Among the analogs, FC-336, a p-xylylendiamine derivative having two FC-303 moieties, showed the most potent inhibitory effect on experimental lung metastasis produced by i.v. co-injection with B16-BL6 melanoma or colon 26 M3.1 cells in a dose-dependent manner. Multiple administrations of FC-336 after tumor inoculation also showed efficient therapeutic potency against spontaneous lung metastasis of B16-BL6 melanoma in mice. Furthermore, FC-336 effectively inhibited the invasion, migration and adhesion of tumor cells in vitro, but its inhibitory effects were not more than those of RGDS peptide. Zymography analysis revealed that FC-336 inhibited the degradation of gelatin substrate by matrix metalloproteinases (MMPs) produced by tumor cells, while the RGDS peptide did not affect the enzymatic degradation. These findings indicate that the pseudo-peptides of the RGD sequence, possessing the inhibitory property of the degradation by MMPs differently from original RGD-containing peptides, may be advantageous and useful in preventing tumor metastasis.

Adjuvant Activity of Mycoloyl Derivatives of N-Acetylmuramyl-L-alanyl-D-isoglutamine in Mice and Guinea Pigs

guinea pigs and in the circulating antibody formation to bacterial ƒ¿-amylase (Bƒ¿A) in mice. However, it was inactive as an adjuvant in cell-mediated cytotoxicity in allogeneic mice in vivo (2). Previously, we reported that 6-O-mycoloyl-N-acetyl muramyl-L-alanyl-D-isoglutamine was active as an adjuvant in cellular immune response such as induction of cell-mediated cytotoxicity to mastocytoma P815-X2 in allogeneic mice, but less effective concerning humoral immune response in vitro or the functions of helper T cells (3). This note deals with the effectiveness of the derivatives of N-acetylmuramyl dipeptide, in which mycolic acids are combined at various positions, with respect to adjuvant activity in mice and guinea pigs. Mycolic acid purified from defatted cells of Mycobacterium smegmatis was used for the syntheses of the derivatives of N-acetylmuramyldipeptide in these experiments. The average molecular formula and molecular weight of the mycolic acid were determined as C80H158O3.5 and 1176.38, respectively. The chemical syntheses of various mycoloyl derivatives of N-acetylmuramyldipeptide will be reported elsewhere (Kusama et al, in preparation). Adjuvant activity in the induction of delayed-type hypersensitivity to ABA-N-acetyltyrosine