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An excess of adult blood adherent cells (monocytes) inhibits mitogen, antigen and allogeneic cell-induced lymphocyte proliferations. This inhibition is dependent on the number of the adherent monocytes in the cultures and is substantially reduced (by 60%) by indomethacin or anti-PGE2 antiserum. Newborn monocytes exert only a weak inhibitory effect and produce about eight limes less PGE2 than adult monocytes. The production of PGE2 and the suppression can be induced by incubating newborn monocytes with mixed leucocyte culture supernatants. Both monocytes from mothers at the time of delivery and from newborn infants, usually exert a poor suppressive activity related to a low production of PGE2. We strongly suggest that the expression of the PGE2-mediated suppression by monocytes is under the control of activated short-lived suppressor lymphocytes. [ABSTRACT FROM AUTHOR]

A competitive enzyme immunoassay for rat growth hormone (rGH) has been developed using polyclonal anti-rGH antibodies and an acetylcholinesterase (EC 3.1.1.7.) enzymatic tracer coupled covalently with rGH. The assay was performed in 96-well microtiter plates coated with rabbit polyclonal anti-goat immunoglobulin antibodies. Molecular sieve filtration and Western blot analysis revealed a single immunoreactive peak for rat plasma or pituitary extracts. Cross-reactivity with other rat pituitary hormones or human GH was less than 1%. Assay of samples in a concentration range of 0.7 to 69 ng/ml by enzyme immunoassay and radioimmunoassay were well correlated (r = 0.87 and 0.85 respectively for plasma and culture medium samples). Intra- and inter-assay variations in plasma were 4 (n = 24) and 14% (n = 9) respectively. Minimal detectable amounts of rGH were 0.6 ng/ml. A two-site immunometric assay also developed with the same antibodies allowed a detection threshold of 0.25 ng/ml.

A new enzyme immunometric assay of small haptens containing primary amino groups (thyroxine, MW 777; substance P, MW 1347; endothelin, MW 2492) is described. The procedure involves different sequential steps: (1) immunocapture of the haptens (standard or sample) by monoclonal anti-hapten antibodies coated on 96-well microtiter plates; (2) cross-linking of haptens via their amino groups to the wells using homobifunctional reagents (glutaraldehyde or disuccinimidyl suberate); (3) denaturing treatments (HCl or methanol); (4) measurement of linked epitope using the same monoclonal anti-hapten antibodies labeled with acetylcholinesterase. A minimal detectable concentration in the 4-10 fmoL/mL range was observed. Each assay appeared to be 70-200 times more sensitive than conventional competitive enzyme immunoassay using the same monoclonal antibody-coated plate technology and acetylcholinesterase-hapten conjugates as enzymatic tracers. Precision and specificity were very satisfying. Good correlation was noted between this assay and the competitive assays performed for different biological samples (plasma, tissues, or supernatant cell culture).

Thromboxane A2 (TXA2) and prostacyclin (two prostanoids) are produced from arachidonic acid through the cycloxygenase pathway. The enzyme cyclooxygenase is inhibited by aspirin. Prostanoids are short-lived and thus exert their effects locally. Activated platelets synthetize TXA2 which reinforces activation of those platelets and platelets in the vicinity of the former. Complete activation however can occur in the absence of TXA2 synthesis. Prostacyclin is able to block all the platelet responses, but this would be achieved in vivo together with intense vasodilation. Primary adhesion remains unaffected, since it does not require platelet activation. There are other molecules endowed with inhibitory effects on platelets: PGD2, PGE1, adenosine, and EDRF (nitric oxide). These molecules, and prostacyclin, also have effects on other cells than platelets and smooth muscle cells: leukocytes, endothelial cells. Clinical investigations on the prostanoid system in physiology and pathology of the cardiovascular system have been hampered by analytical problems. Taking into account all these restrictions, a rational pharmacological approach is difficult, but newer molecules with dual and selective activity against TXA2 (both inhibitor of TX-synthetase and antagonist at the TXA2-receptor level) seem promising as anti-thrombotic agents.

A new technic named viroimmunoenzymoassay is described. The principle is the same as the classical viroimmunoassay which uses as tracer a bacteriophage bound covalently to an hapten. Immuno-specific neutralization of these modified bacteriophages by an hapten antiserum allows to detect and to test hapten antibodies or the haptens with a great sensitivity. In the new technic the visualization of the bacterial lysis is estimated by measure of the amount of beta-galactosidase which is released into the medium by Escherichia coli BB bacteria. These are previously induced by isopropyl thiogalactoside or lactose. The method is applied to the assay of penicilloyl groups bound covalently with another molecule, and its performances are compared with three other classical immunological methods: the radio-, enzymo- and viroimmunoassay.

After growth in Difco Nutrient Broth, several proteolytic enzymes are excreted by B. subtilis, Marburg strain, namely a metalloprotease and a seryl protease. We report here the purification and some biochemical properties of a third extracellular hydrolytic enzyme for which we propose the term of esterase. As the serylprotease, the esterase is a seryl enzyme endowed with both proteolytic and esterolytic activities. Nevertheless the esterase differs from serylprotease in many aspects. In particular, it is an acidic enzyme with a low proteolytic activity and a high esterolytic activity. Its specificity toward synthetic substrates is restricted. The enzyme is active only on esters of amino acids and particularly on those of tyrosine. With Bz Tyr O Et as substrate the esterase displays a maximum of activity between pH 7.2 and 8.1 with a Km of 1.3.10-minus 3 M at 30 degrees C. At the end of this work, two questions remain unanswered: 1) the origin of the multiplicity of the bands revealed by polyacrylamide electrophoresis in the purest fraction; 2) the nature of the physiological substrate of the enzyme.

We report 8 cases of familial lymphohistiocytosis collected in 6 families. Several data argue for an hyperactivation of the reticuloendothelial system (RES). An abnormal visualization of all organs was observed in a scintigraphic study after 99technetium labelled red blood cells injection. Blood monocytes contained very low peroxidase activity as detected by cytoenzymology and secreted large quantities of prostaglandin E2 (PGE2). Adherent cells isolated from blood exercised a strong suppressor effect on the proliferation of normal lymphocytes induced by phytohemaglutinin. This effect was reduced by indomethacin and therefore appears PGE2-dependent. One patient's serum exerced an inhibitory activity on antigen-induced proliferation of normal lymphocytes and on mixed leucocyte reaction. In contrast, cellular and humoral functions were not deeply impaired. The hyperactivation of the RES remains unexplained and not related to a graft versus host reaction, which could be excluded in 3 of our patients. Therapeutic attempts were not efficient, all patients dying despite steroid, vincaleucoblastin and indomethacin therapy.

An excess of adult blood adherent cells (monocytes) inhibits mitogen, antigen and allogeneic cell-induced lymphocyte proliferations. This inhibition is dependent on the number of the adherent monocytes in the cultures and is substantially reduced (by 60%) by indomethacin or anti-PGE2 antiserum. Newborn monocytes exert only a weak inhibitory effect and produce about eight times less PGE2 than adult monocytes. The production of PGE2 and the suppression can be induced by incubating newborn monocytes with mixed leucocyte culture supernatants. Both monocytes from mothers at the time of delivery and from newborn infants, usually exert a poor suppressive activity related to a low production of PGE2. We strongly suggest that the expression of the PGE2-mediated suppression by monocytes is under the control of activated short-lived suppressor lymphocytes.