Cytotoxic and stimulatory effects of antilymphocyte globulin (ALG) on hematopoiesis

Four different preparations of antilymphocyte/antithymocyte globulin were tested in vitro for their toxicity to lymphocytes and to hematopoietic precursor cells, depending on concentration and time. Complete lymphocytotoxicity was observed at concentrations from 6.3 to 25 micrograms/ml, and suppression of colony formation by hematopoietic precursors was seen at concentrations from 12.5 to 250 micrograms/ml. Prolonged incubation time did not increase lymphocytotoxicity but augmented precursor cell damage. Lymphocytotoxicity was comparable among the four preparations tested whereas precursor cell toxicity varied widely. Antilymphocyte globulin is mitogenic and stimulates the release of hematopoietic growth factor activity by peripheral blood cells. Absorption of ALG with human T-cells eliminated precursor cell toxicity and mitogenicity but not the capacity to release hematopoietic growth factors. These results show that dose/time schedules for ALG administration may be relevant and ALG acts by virtue of inhibitory and stimulatory antibody effects.     

The effect of antilymphocyte globulin (ALG) on human lymphocytes in vitro: inhibition of lymphotoxin production as a sensitive indicator for ALG activity.

The effect of antilymphocyte globulin (ALG) on lymphocyte function in the presence or absence of complement was investigated by comparing (i) ALG-induced blast-cell transformation, (ii) lymphotoxin production and (iii) its effect on PHA-induced blast-cell transformation, and on (iv) lymphotoxin production and (v) its cytolytic effect on lymphocytes. The most striking observation was that even extremely low doses of ALG were able to suppress significantly the lymphotoxin production without affecting other lymphocyte functions or cell viability; this effect was found to be independent of complement. From the comparisons of the mitogen-induced lymphocyte function in the presence of varying doses of ALG and PHA it can be concluded that ALG exerts its inhibitory effect on lymphokine production most likely by interfering with mitogen recognition rather than lymphokine secretion.     

Effect of recombinant human alpha interferon (INF) and antilymphocyte globulin (ALG) on normal and aplastic anaemia haematopoietic progenitor cell growth.

The effect of recombinant alpha interferon (INF) and of antilymphocyte globulin (ALG) to the colony stimulating factor (CSF) production was examined with in vitro culture of the bone marrow of healthy and of aplastic anaemia (AA) persons. In healthy persons the supernatant of lymphocytes preincubated with PHA and ALG was found to show a stimulating effect to clonogenic properties of marrow progenitors, the mentioned effect being not in proportion to the concentration value. Similar properties are shown by interferon in these persons. In patients with aplastic anaemia, a considerable stimulating ALG effect to the granulocytic formation of colonies and a lesser stimulating effect of interferon were shown.     

Use of antilymphocyte globulin in autoimmune nervous system diseases]

The pathogenetic bases for the indication of immunosuppression in multiple sclerosis are represented in a survey, rested upon experiences in the clinical compatability test of AHLG Dessau. The knowledge gained in animal experiments and epidemiology in recent years is considered and problems of membrane, slow-virus hypothesis, genetic problems and changes of immunoglobulins and lymphocytes are critically referred to.     

The effect of various antibiotics on the formation of typhus antibodies following immunization with typhus vaccine]

It was shown that administration in the course of one week, before or after a single use of killed or chemical typhoid vaccine of dibiomycin, biomycin, or biomycin in combination with erythromycin in comparatively high doses produced no negative effect of the production of typhus antibodies and the intensity of antitoxic immunity in albino mice. The same antibiotics failed to influence the antibody formation in guinea pigs if they produced no toxic effect on the animals; but in case of development of toxic phenomena connected with the administration of the mentioned antibiotics a strong depression of antibody production was observed in guinea pigs.     

The suppressive effect of metabotropic glutamate receptor 5 (mGlu5) inhibition on hepatocarcinogenesis

Metabotropic glutamate receptors (mGlus) are G-protein-coupled receptors playing an important role in the central nervous system (CNS). Recently, mGlus have been identified in peripheral tissues, and aberrant expression or inhibition of the receptors functions in the development of certain cancers. However, the correlation of mGlu activity with hepatocellular carcinoma (HCC) remains unknown. In this study, we analyzed the effects of inhibiting mGlu5 activity in hepatocarcinoma cell lines and a xenograft model. Inactivation of mGlu5 with 2-Methyl-6-(phenylethyl)-pyridine (MPEP), a specific antagonist of the receptor, caused inhibition of cell growth, migration, and invasion of HepG2 and Bel-7402 cells, assessed by MTT assay, ATP production, wound healing, and Boyden chamber assay, respectively. Moreover, inhibition of tumor growth and the potential metastasis of hepatocellular carcinoma were also found in nude mice. Furthermore, mGlu5-mediated extracellular signal-regulated kinase (ERK) phosphorylation has been found to be partially involved in cell growth and migration, as detected by stimulation of (S)-3,5-Dihydroxyphenylglycine (DHPG), an agonist of the receptor, and blockage of MPEP and U0126, an inhibitor of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (MEK). These data indicate that inhibiting the activity of mGlu5 has the molecular potential to suppress oncogenic actions by blocking downstream effector molecules. The study suggests that mGlu5 activity may contribute to understanding the development of HCC.     

Use of the immune tolerance induction in the production of an antilymphocyte serum (ALS) free of antibodies against serum proteins]

The possibility has been investigated of a direct gain of ALS free of undesirable antibodies against serum proteins by inducing immunologic tolerance in productive animals (pigs). Preliminary experiments made with tolerogenic amounts of 10 and 50 ml of sera and with immunization by the serum alone proved applicability of this method. Electrophoresis showed antibodies against 6 to 7 and 2 to 3 fractions in animals tolerated with 10 and 50 ml respectively, compared to 18 to 20 fractions in the control group, which was not tolerated. This has been confirmed when preparing ALS in practice, where the toleration was carried out with 25 ml of serum or with the same amount of serum with the addition of hemoglobin and immunization by lymphocytes isolated from peripheral blood. Final ALS of untolerated animals contained antibodies against 7 to 8 fractions, whereas that of experimental group tolerated with serum and Hb was free of antibodies against serum protein, hemoglobin included. ALS of the group tolerated with normal serum contained only antibodies against hemoglobin. In vitro tests (i.e. lymphoagglutination t., lymphocytotoxicity t., rosette inhibition t.) proved that by inducing tolerance towards serum protein the activity of ALS was in no was affected. According to the results this method can be employed not only for the preparation of ALS, but also for other purposes, such as preparation of monovalent antisera for immunoelectrophoresis.     

Nonspecific suppressive effect of Ehrlich tumor ascitic fluid on transplantation immunity]

The influence of syngeneic Ehrlich ascites tumour fluid on the survival of allogeneic skin allografts was investigated on CC57BR mice. A 3--4-day delay of the allograft rejection in mice injected with ascitic fluid was revealed. Preliminary transplantation of such allograft to mice with Ehrlich tumour produced no intensification of the immunodepressive action of the ascites fluid obtained from them. The data obtained indicated the preferential significance of the antigen-independent immunosuppressive factors of ascites tumour fluid in the suppression of the transplantation immunity in vivo.     

The effect of gamma irradiation on the direct intercellular interaction (rosette formation) of thymic macrophages with thymocytes]

In experiments with (CBA x C57BL/6)F1 mice, the effect of radiation on rosette formation between thymus macrophages (Th-MPh) and thymocytes (Thc) was studied on days 1, 4, 12, 30, and 60 following gamma irradiation with doses of 0.5, 2, 4, and 8 Gy. The influence of supernatants of thymus epithelial cells (EC) on the rosette formation was estimated. Gamma irradiation with doses of above 2 Gy was shown to cause a dose-dependent inhibition of rosette formation of Th-MPh with Thc in vitro. Recovery of rosette-forming ability of Th-MPh was observed on day 60 of the experiment. Two types of rosette-forming Th-MPh were identified: RFMPhII with low rate of binding to Thc and RFMPhII with high rate of binding to Thc. Radiation affects mainly the RFMPhII content. With radiation doses of 4 and 8 Gy no complete restoration of RFMPhI was observed on day 60. The total population of rosette-forming Th-MPh was restored on day 60 mainly due to cells with low rate of rosette formation. The EC supernatant promoted rosette formation of exposed Th-MPh with Thc. The effect was maximum at early times following irradiation of Th-MPh with a dose of 4 Gy.