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P Lefrancier

Publications and source records attributed to P Lefrancier.

At least 37 records · Page 2Linked to original sources
PubMed1981

[Role of zinc and other metals in the biological activity of the serum thymic factor (thymulin)].

The serum thymic factor (FTS) used in synthetic or natural form, loses its biological activity after passage on a chelating agent, Chelex 100. Such activity is recovered after addition of zinc and, to a lesser degree, of certain other metals. FTS activation is secondary to zinc binding to the peptide. These results indicate the existence of two FTS forms: the first one, deprived of zinc and biologically inactive, the second one containing zinc and biologically active, for which we purpose to coin the name of thymulin.

Animals↗
PubMed1980

Macrophage stimulation in vitro by an inactive muramyl dipeptide derivative after conjugation to a multi-poly(DL-alanyl)-poly(L-lysine) carrier.

It has been previously reported that N-acetyl-muramyl-L-alanyl-D-isoglutamine (MDP), which represents the minimal structure that can substitute for mycobacteria in Freund complete adjuvant, activated macrophages in vitro and in vivo. In the present study we show that, in contrast to MDP, the nonadjuvant MDP(DD) stereoisomer has no effect on cytostatic activity of thioglycolate-induced macrophages as measured by uptake of [3H]thymidine. However, surprisingly, after conjugation to an inert carrier, multi-poly(DL-alanyl)-poly(L-lysine), this compound activates macrophages in vitro and becomes at least as effective as MDP. It has also been shown in other studies that after conjugation MDP(DD) remained devoid of antigenicity and of adjuvant activity although such a conjugate could increase resistance to infection. It, therefore, appears that there exists no correlation between the structure required for adjuvant activity and the structure required for macrophage activation or for enhancement of nonspecific immunity.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1979

Synthesis of N-acetyl-muramyl-L-alanyl-D-glutamic-alpha-amide(MDP) or -alpha-methyl ester derivatives, bearing a lipophilic group at the C-terminal peptide end.

We report the synthesis of nine lipophilic derivatives of N-acetyl-muramyl-L-alanyl-D-glutamic-alpha-amide (MDP) or -alpha-methyl ester in which the gamma-carboxyl function of the D-glutamyl residue is either esterified by a medium chain alcohol or substituted by an L-alanyl residue esterified by a medium or long chain alcohol. A new method is described which easily allows one to obtain derivatives of MDP, bearing a free or substituted amino-acyl or peptidyl residue on the gamma-carboxyl function.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1978

In vivo and in vitro stimulation of nonspecific immunity by the beta-D-p-aminophenyl glycoside of N-acetylmuramyl-L-alanyl-D-isoglutamine and an oligomer prepared by cross-linking with glutaraldehyde.

Several biological activities of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP for muramyl dipeptide), a synthetic immunoadjuvant, are inhibited after glycosidation with p-aminophenol. Thus, this glycoside does not induce an increase humoral antibody response in mice when injected in saline, although it retains its stimulatory effect on circulating antibodies and delayed hypersensitivity after administration in a water-in-oil emulsion. The capacity of MDP to stimulate mouse spleen cells is lost, and, moreover, the analogue is unable to increase nonspecific resistance to infection under conditions where MDP is active. After cross-linking of the beta-D-p-aminophenyl glycoside of MDP with glutaraldehyde, several biological activities of MDP are recovered. Moreover, the cross-linked oligomer (molecular weight, approximately 6,000 daltons) is able to stimulate the uptake of thymidine by spleen cells from a strain of mice weakly responsive to MDP and is more active than MDP in protecting mice against bacterial challenge.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1976

Modulation of the immune response by a synthetic adjuvant and analogs.

N-Acetylmuramyl-L-alanyl-D-isoglutamine increases the humoral immune response of mice when given in aqueous media instead of the usual water-in-oil emulsions. Moreover, this compound is adjuvant active even by the oral route. In view of studying the relation between chemical structure and biological activity, several synthetic analogs were tested. The immune response could be modulated according to chemical modifications, and the synthetic analog with D- in place of L-alanine was shown to inhibit the immune response.

Adjuvants, Immunologic↗