Biomedical subjects
Publications and source records attributed to M Guiguet.
The use of DNA synthesis as a measure of mitogenic activity in lymphocytes is reanalyzed in the light of the Continuum Model, and it is suggested that although lymphocytes may have a linear response with regard to mitogen concentration, the curves using thymidine may show a threshold response at low concentrations and a decrease in activity at high concentrations.
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The fraction of complement C3, the total complement activity and the levels of IgG, IgA and IgM immunoglobulins have been estimated in the third trimester of pregnancy in 70 control pregnant women and in 38 hypertensive pregnant women who presented either with "pure toxaemia" or with "superimposed toxaemia". The level of IgG is definitely but not significantly lowered in cases of "pure toxaemia". The other parameters that were studied showed no notable changes in comparison with control pregnant women.
We investigated the role of human interleukin-6 (IL-6) in the regulation of the third component of complement (C3) biosynthesis by cultured rat liver epithelial cells. A natural human IL-6 (nh IL-6) preparation was shown to up-regulate C3 production, whereas an Escherichia coli-derived recombinant human IL-6 (rh IL-6) displayed no activity on C3 biosynthesis. However, the C3-stimulating activity of the nh IL-6 preparation was only partially reduced when treated with an antihuman IL-6 monoclonal antibody. Binding studies indicated that although it was devoid of any C3 stimulating activity, rh IL-6 specifically bound to hepatic cell receptors (Kd = 0.38 nM) and possessed the same binding affinity as nh IL-6. Furthermore, the substitution of natural IL-6 molecules for the recombinant IL-6 led to the recovery of the initial C3-stimulating activity. These studies demonstrated that human IL-6 alone does not stimulate rat liver epithelial cell C3 production but is able to accentuate the C3-stimulating activity of unrecognized components which are present in the nh IL-6 preparation. Human IL-6 thus appears to act as a co-factor for the up-regulation of hepatic C3 production.