Nonspecific inhibitory activity of soluble human colon carcinoma extracts: tentative mechanism of action.

Soluble human colon carcinoma extract(s) (SCE) were potent nonspecific inhibitors of lymphoproliferative responses to mitogens. Inhibition was concomitant with induction in about 35% of cells of morphologic alterations for most of them comparable with the ones observed in mitogen-induced blast cells. Nonetheless, these blastlike cells did not proliferate. SCE did not interfere with mitogen binding to cell receptors. Moreover, SCE was unable to induce or activate suppressor cells, and its primary target cell was the unresponsive lymphoid cell itself. The inhibitory effect of SCE was early and irreversible. The differential activity of SCE can be correlated with an early [3H]uridine uptake, which was inhibited 6 hours later, as seen for the other biochemical parameters of cell activation. Also, SCE altered membrane-bound ATPase activities. Na,K-ATPase was strongly inhibited, whereas Ca2+-dependent and Mg2+-dependent ATPases were stimulated. These observations were discussed as an SCE-lymphocyte plasma membrane interaction translated into differential signals to the intracellular metabolic pathways.

Immunomodulating activities associated with the cytosol fraction of a 3-methylcholanthrene-induced rat fibrosarcoma.

Cytosol fraction(s) from McFiFi2(s) fibrosarcoma cells (Fcc), isolated from either cultured cells or solid tumors induced in F344 rats, produced a dose-related inhibition of lymphoproliferative responses to several mitogens, whatever the lymphoid organ or the animal species used as the source of lymphocytes. Only stimulated human lymphocytes were not Fcc inhibited; instead, Fcc was a potent stimulator of their spontaneous proliferation. Fcc cytostatic activity was not effective in various cycling cell lines and was restricted to mitogen-stimulated lymphocytes. Fcc, a primary tumor product, did not induce suppressive cells and was unable to prevent mitogen cell surface binding. However, expression of its modulating effect was accelerated by the simultaneous presence of the mitogen. Moreover, Fcc produced its suppression by interrupting lymphocyte activation at some point within the G0-G1-phase transition. Molecular sieving showed that Fcc contains at least two factors with suppressive (mol wt, approximately 3,000) and stimulatory (mol wt, greater than 5,000) activities, respectively.

Effect of concanavalin A on membrane-bound enzymes from mouse lymphocytes.

The ionic influence and ouabain sensitivity of lymphocyte mg-2+-atpase and Mg-2+-(Na+ +K+)-activated ATPase were studied in intact cells, microsomal fraction and isolated plasma membranes. The active site of 5'-nucleotidase and Mg2+-ATPase seemed to be localized on the external side of the plasma membrane whereas the ATP binding site of (Na+ +K+)-ATPase was located inside the membrane. Concanavalin A induced an early stimulation of Mg2+-APTase and (Na+ +K+)-ATPase both on intact cells and purified plasma membranes. In contrast, 5'-nucleotidase activity was not affected by the mitogen. Although the thymocyte Mg2+-ATPase activity was 3-5 times lower than in spleen lymphocytes, it was much more stimulated in the former cells (about 40 versus 20%). (Na+ +K+)-ATPase activity was undectectable in thymocytes. However, in spleen lymphocytes (Na+ +K+)-ATPase activity can be detected and was 30% increased by concanavalin A. Several aspects of this enzymic stimulation had also characteristic features of blast transformation induced by concanavalin A, suggesting a possible role of these enzymes, especially Mg2+-ATPase, in lymphocyte stimulation.

Presence of free light chains in urine of patients suffering from subacute sclerosing panencephalitis.

The immunoelectrophoretic analysis of CSF of patients suffering from subacute sclerosing panencephalitis (SSPE) showed modifications in the IgG pattern. Using the same method and also the double diffusion in agar technique we have revealed in these patients the presence of free light chains in most urines studied. Isofocusing analysis of free light chains from urines of two patients suggests that these chains could be a monoclonal product.

What can be measured with RAST?

A theoretical study of the basic principles involved in Radioallergosorbent test (RAST) showed that: 1) When a given serum is tested, the significance of the numerical value obtained with RAST depends upon the serum assayed and the allergosorbent preparation, in a rather unpredictable way. Three factors can be measured: a) The percentage of specific IgE antibodies among all allergen-specific antibodies; b) The specific IgE antibody level; c) The product of the specific IgE antibody level and its affinity constant. 2) Simple graphical techniques allow a straightforward determination of all these factors if four dilutions of each serum are assayed at the same time. The results are expressed in two constant parameters (arbitrary IgE unit and allergosorbent capacity). It is concluded that these theoretical calculations may give a fair account of a lack of correlation between specific IgE antibody levels (as assayed with RAST) and several clinical and biological parameters. Furthermore, they provide a simple procedure which makes such tedious manipulations as specific IgE antibody purification quite necessary.

Evaluation of intercellular adhesion with a very simple technique.

Rosetting techniques are widely used to quantify or purify various lymphocytic subpopulations; however, these techniques cannot discriminate between different receptors of similar specificities and different binding strengths, further, they do not provide any information concerning the molecular mechanisms involved in cell-cell adhesion. This paper describes a very simple technique of assaying rosette stability: cell suspensions are driven with known pressure through a calibrated needle with a syringe. Adhesion is quantified before and after this treatment. This procedure did not damage rat peritoneal cells used in a model system. Further, this method yielded fairly reproducible results and allowed a crude estimate of the force involved in the binding of glutaraldehyde-treated sheep red cells (GSRC) or immunoglobulin-coated sheep red cells (IGSRC) by rat macrophages (an average force of 0.8 x 10(-7) Newton was needed to separate 50% of bound IGSRC from macrophages). Binding and binding strength were found to be independent parameters. Last, this method possibly provided a way of separating two distinct subpopulations of rat macrophages. It is suggested that this technique might be routinely used to refine rosette studies.

Detection of HTLV-I (human T-cell lymphotropic virus, type I) proviral DNA in leukemic cells from a French patient with Sezary syndrome.

Human T-lymphotropic type I (HTLV-I) proviral sequences were detected in leukemic cells of a patient living in Marseilles (south of France) and suffering from Sezary syndrome. He did not have any travel history outside France and did not receive blood transfusion or hepatitis B vaccination. This case of HTLV-I positive Sezary syndrome is the first one described outside the known endemic regions for HTLV-I. Moreover, this patient was found to be negative for viral antibodies. This observation should therefore stimulate new and thorough analysis of the association of this human retrovirus with leukemia and lymphoma in the Mediterranean region, both by seroepidemiological and molecular biology techniques.

Non-specific immunoregulatory factors in the cytosol fraction of human trophoblast.

Cytosol extracts from syncytiotrophoblast of human placenta (HP) have been shown to contain substances capable of suppressing the proliferation of normal human lymphocytes stimulated by mitogens. This suppressive effect has also been observed on lymphocytes stimulated by mitogens and by allogenic cells in various species. The extracts did not, however, inhibit spontaneous (i.e. unstimulated) lymphoproliferation. In addition, HP in some cases exercised an immunostimulatory effect solely on stimulated fractionated lymphocytes. In preliminary experiments the suppressive activity was shown to depend on at least two factors: the first had the ability to bind the mitogen while the second acted irreversibly after 8 h of contact on the lymphocyte itself and was thermostable.

Immunosuppressive properties of human placenta: study of supernatants from short-term syncytiotrophoblast cultures.

Using collagenase and mechanical treatment to attempt to eliminate cellular contamination such as macrophages and decidual cells, trophoblast enriched cell suspensions were isolated from the human placenta. With a view to assessing the role of trophoblast in impairing maternal rejection of the fetus, supernatants (SPl4) were prepared from these placental cells after short-term culture (4 h). The immunosuppressive activity of these supernatants was studied following application to mitogen-stimulated human lymphocyte cultures and mixed lymphocyte cultures. In both cases a reproducible inhibition was observed. The ability of these substances to induce a non-specific inhibitory effect was ascertained by observing mouse lymphocyte responses to mitogens or alloantigens. To gain further insight into in vivo fetal protection against anti-paternal cells, we also examined the effects of SPl4 on CTL generation. It was found not only that CTL generation was markedly depressed but also that SPl4 drastically impaired cell-mediated lympholysis at the effector level. To characterize the factors involved in our observations, SPl4 was subjected to dialysis and to chromatography. In the first case, it was found that these factors were not amenable to dialysis. In the second case, we obtained on an Ultrogel AcA 44 column two fractions with immunosuppressive activity. Following our previous work on human syncytiotrophoblast, we analyzed only the low molecular weight inhibitory fraction, which was chromatographed again on Ultrogel AcA 202. The molecular weight of the immunosuppressive factor(s) was estimated to be around 3.5 kDa. We postulate that human trophoblast releases soluble factors around the fetus which may act to protect it against maternal immunological rejection.

Immunoregulatory activities of human trophoblasts mediated by polyamine complexes.

In a previous publication we described the presence in human placenta (HP) of immunosuppressive factors inhibiting the lymphoproliferative responses to mitogen. The results of further study reported herein indicate that the substance involved is of a syncytiotrophoblastic origin, that it is thermostable to 100 degrees C for 1 hr, and of low molecular weight, i.e. 3,500. It was defined as a polyamine conjugate with nucleic acids. Trophoblast cell extracts lost their immunosuppressive ability after heating in cultures of human lymphocytes supplemented with 5% autologous serum. These effects were, however, preserved both in cultures assayed in 5% fetal calf serum and in those to which purified polyamine oxidase (PAO) was added to autologous serum. Trophoblast cell extract was found to contain polyamine oxidases. Placental PAO can be inhibited by quinacrine a typical inhibitor of flavoprotein enzymes but not by isoniazid, an inhibitor of pyridoxal enzymes; this would suggest that the enzymes in human placenta are of a tissular rather than seric origin. The implication of these observations is that immunosuppression is mediated by oxidative products issued from an interaction between polyamine and polyamine oxidase in the syncytiotrophoblast cytosol. This interaction may constitute the basis for a local immunological barrier and may be involved in the protection of the fetus against maternal immune rejection.

Evidence for the presence of lambda chain dimers in cerebrospinal fluid of patients suffering from subacute sclerosing panencephalitis.

The presence of free lambda chain dimers in the CSF of selected patients suffering from subacute sclerosing panencephalitis was proved by use of agar double diffusion and immunoelectrophoresis. The significance of this finding is discussed.

[Immunochemical study of liver metastases of colonic tumors]. / Etude immunochimique des métastases hépatiques de tumeur colique

This work demonstrated that anti-CEA and anti-NCA antibodies can be obtained from liver metastases of colonic carcinoma. The various antigens that have been identifiedin colonic tumor are found in liver metastases. Furthermore, the healthy parts of a metastatic liver contain not only CEA but also NCA.

[Regulation of lymphocyte responses in vitro: inhibitory effects of rat serum]. / Régulation des réponses des lymphocytes in vitro: effets inhibiteurs du sérum de rat

Previous results on the potentiation by cytochalasin B (CB) of lymphocte responses in vitro, particularly the requirement for serum for this potentiation, prompted us to undertake the present study on inhibitory effects of autologous serum on rat lymphocyte activities. Main results mirror the inverse effect of CB: maximal inhibition is obtained at suboptimal doses of PHA; inhibitory effect bears essentially on early events of activation; high cell density is of prime importance. In contrast to CB, serum affects more 3H-TdR incorporation than blast transformation. Therefore, CB and some serum component(s) could have inverse effects on a single regulatory mechanism: suppressive cellular interactions.