Eberhard Wecker

A third signal in b cell activation given by trf.

There is a wealth of experimental evidence supporting the idea that T cells have to intervene in the immune response to many antigens to ensure an optimal antibody response (Reviewed in Greaves et al. 1973). We have addressed our work to the question at whicli step of B cell activation this intervention is necessary. An in vitro culture system (Mishell & Dutton 1967) was applied using spleen cells of thie functionally athymic nu/nu mice and heterologous blood cells as antigens. SRBC can operationally be defined as T cell dependent antigens since the IgM immune response in T cell deprived cultures is far from the optimal response obtained in the presence of T cells (Schimpl & Wecker 1970). In an attempt to restore the immune response in T cell deprived cultures with thymocytes we found that allogeneic thymocytes were greatly superior to syngeneic ones (Schimpl & Wecker 1971). Subsequent experiments showed that the effect could be ascribed to a soluble factor produced by allogeneically or Concanavalin A (Con A) stimulated T cells (Schimpl & Wecker 1972, Wecker et al. 1974). Soluble mediators with similar T cell replacing activities have now been described by many different groups (Dutton et al. 1971, Doria et al. 1972, Gorczynski et al. 1972, Feldmann & Basten 1972, Britton 1972, Sjoberg et al. 1972, Gisler et al. 1973, Rubin et al. 1973, Waldmann & Munro 1973, Watson 1973, Kishimoto & Ishizaka 1973, Amerding & Katz 1974), some factors being obtained from T cells, activated by antigen in vivo and incubated with the same antigen in vitro. The assumption imderlying all further considerations is that such mediators are regularly produced upon stimulation of T cells and that they

Expression of MuLV GP71-like antigen in normal mouse spleen cells induced by antigenic stimulation.

ALL mouse strains investigated possess cellular DNA sequences which are homologous to the genomes of endogenous C-type particles1. Also, major envelope glycoproteins of the oncoviruses2, such as GP71, are found on the surface of normal cells and they display a considerable polymorphism. An antigen serologically indistinguishable from AKR murine leukaemia virus (MuLV) GP71 is present in normal bone marrow cells of all mouse strains investigated but not in normal spleen cells3. Allogeneic4 and mitogenic stimulation5,6 of spleen cells have been reported to result in C-type particle synthesis in some but not all mouse strains. We report here that both T and B lymphocytes of mice express a GP71-like antigen on their surfaces if antigenically stimulated.

Properties of mouse leukemia viruses. Xiii. Serum therapy of virus-induced murine leukemias.

Abstract Treatment of STU mice with antiserum to the major glycoprotein (gp71) of Friend leukemia virus (FLV) was therapeutically active against massive infection with Friend or Rauscher viruses, whereas similar treatment with antisera to p12 and p15, two other proteins of the virion which are involved in surface reactions, were not effective. A more thorough study showed that the active principle is contained in the IgG fraction of gp71 antiserum and that treatment with this can lead to complete recovery of the mouse from FLV infection. As a consequence of the treatment, the host produces type-specific antibodies which are detectable by neutralization, radioimmunoassay with FLV gp71, and cytotoxic tests on FLV-infected cells. No significant change was observed in the pattern of autogenous antibodies directed against an AKR-type gp71 already present in normal mice. Treatment with immune serum instead of immune IgG or treatment with immune IgG at a later stage of infection with FLV (after 7 days p.i.) did not result in complete recovery of the mice. Paralysis of the host immune system by serum proteins and Friend virus, respectively, seems to be responsible for these phenomena. Some indication was obtained that the viral-induced paralysis can be overcome by combined inoculation of heterologous immune IgG and normal isogenic spleen and bone marrow cells.

Some properties of an infectious ribonucleic acid from mouse encephalomyelitis virus

Abstract An infectious nucleic acid fraction has been prepared from brains of mice infected with mouse encephalomyelitis virus. The infective principle of this fraction appears to be ribonucleic acid, since it is highly sensitive to RNAase and completely resistant to DNAase. Further it can be precipitated by 1 M NaCl under conditions where only RNA precipitates. The source of the infectious RNA from infected brain material is a structure resistant to RNAase and which can be purified by treatment with fluorocarbons. It is in all probability the infectious virus particle. This hypothesis has been confirmed by isolation of the infectious RNA from highly purified virus preparations. A detailed analysis of the dose-response curves suggest that the high molecular weight DNA in the crude fractions can inhibit the biological activity of the RNA.

Studies on the source and action of the T-cell replacing factor (TRF).

We have recently reported that in the in vitro system of Mishell and Dutton (1) in which normally the 19s response is strongly T-cell dependent (2) the T-cell function can be replaced by a soluble factor (3). This soluble factor was derived from supernates of allogeneic spleen cells incubated for 24 hrs. and was called T-cell replacing factor, TRF. Our published data showed that the formation of TRF was dependent on the presence of T-cells and we suggested that TRF was actually a T-cell product. To substantiate this idea we now used allogeneic cells from different sources, that is, spleens, lymph nodes and thymus. Since the thymocytes contain a very small number of mature cells (4) which might be expected to participate in TRF production, the product derived from allogeneic thymocytes was fivefold concentrated.

Properties of mouse leukemia viruses XVII. Factors required for successful treatment of spontaneous AKR leukemia by antibodies against gp71

Abstract AKR mice were treated with heterologous anti-gp71 antibodies under various conditions in order to establish the optimal criteria for effective suppression of leukemia development. The strongest effect was observed when mice were treated at birth; and when this regimen was used, prior treatment of the mothers did not provide additional protection. If treatment was delayed until Day 3 ( Schwarz et al. , 1979 ), the beneficial effect of the serum diminished sharply, emphasizing the presence of a narrow window very early in the life of the AKR mouse when antibody must be present in order to have an effect on subsequent leukemia development. A number of parameters were examined in the experimental mice and as in our previous study ( Schwarz et al. , 1979 ), suppression of leukemia, which occurred in 68% of the animals, correlated with elimination of viremia and appearance of natural antiviral antibodies. Interestingly, our results suggest that antibody therapy is primarily effective against the thymic form of the disease. The availability of nonviremic, antibody-positive animals afforded us the opporounity to examine if these characteristics could be transmitted to the offspring. From selected mating crosses, we successfully derived both F1 and F2 generations of AKR mice which possessed high titers of antiviral antibodies and were nonviremic at 21–28 weeks of age. It appeared that a maternal effect may be responsible for this phenomenon. The implications of these findings are discussed in relation to the development of AKR leukemogenesis.

Einbau von radioaktivem Phosphor in das Virus der klassischen Geflügelpest

Der Einbau von 32P in das Virus der klassischen Geflügelpest gelingt, wenn man den Erreger in Gewebekulturen aus Hühnerembryonal-Zellen züchtet, denen radioaktiver Phosphor zugesetzt wurde. Es werden auf diese Weise relativ hohe spezifische Radioaktivitäten bis zu etwa 1500 Impulse/Min./hämagglutinierender Einheit erreicht. Das Isotop wird bei diesem Züchtungsverfahren zu etwa 21% in die Ribonucleinsäure, zu etwa 65% in die Phosphor-Lipoide des Virus eingebaut.

Nonantigen-Specific Lymphokines in T Cell-B Cell Cooperation

Publisher Summary Nonantigen-specific mediators, the lymphokines, are intimately involved in the amplification of many of the cell-mediated immune reactions. The stimulation of T-cells by concanavalin A (Con A) has proved to be particularly well suited for the induction of highly active preparations. A frequently used source of T-cell-replacing factor (TRF)-like molecules are T-cells activated to alloantigens in irradiated semiallogeneic recipients. T-cells required for TRF production carry the Ly 1 + 2- phenotype, which is now being recognized as that of the classical helper cell. The TRF-like molecules are produced within the first 24 hours after the stimulation of T-cells. The production of TRF is also inhibited by the addition of tosyl-L-lysyl chloroketone, an inhibitor of proteases, to the cultures of T-cells confronted with Con A. The chapter illustrates the inhibition of the primary anti-sheep red blood cell (SRBC) response by the addition of isolated Fc-fragments. T-cells may also require a distinct signal before they can become functional effector cells. This signal seems to be mediated by soluble factors produced by other T-lymphocytes. The differentiation of T- and B-cells to their final functional states may be brought about by similar biological mediator substances.

Transcriptional and Post-Transcriptional Control of Ig-Gene Expression in Murine B-Cells Activated by LPS and Anti-Receptor Antibodies

Bacterial Lipopdysaccharide (LPS) induces normal resting B-cells to proliferate and to differentiate into immunoglobulin (Ig)-secreting plasma cells. We have studied the transcriptional control of Ig-gene expression in this system by an in vitro transcriptional run-on assay (1). Fig. 1 shows the relative RNA transcriptional rates in nuclei isolated from resting B-cells and from B-cells 1 to 4 days after LPS stimulation. There are very few if any transcripts demonstrable in resting B-cells with the probes tested (C/u, Igh-enhancer, and kappa). Even actin and H-2 probes do not give strong signals. Upon LPS stimulation, there is a rapid and strong enhancement of RNA Polymerase II activities until day 4, giving 30–50 fold increases. The /u- and kappa-transcripts detectable are about equal, indicating also a balanced distribution of RNA Polymerase II along both heavy and light chain loci. The 30–50 fold increases of transcription upon LPS induction account for the strong accumulation of Ig-mRNAs found in day-4 LPS cultures. The data demonstrate that Ig-gene expression in normal activated B-lymphocytes is regulated primarily at the level of transcription.

II. The RNA Replication of Hydroxylamine-inactivated Polioviruses

If cells are exposed to a mixture of hydroxylamine inactivated and infectious viruses the total rate of viral RNA-replication is lower than if the cells are infected with the same number of infectious viruses alone. This inhibitory influence of inactivated viruses depends on the ratio of infectious: inactivated viruses in the inoculum. One lethal hit by hydroxylamine suffices to produce the effect. In fact, viruses with few lethal hits inhibit more strongly than those with many lethal hits in their genome. There is also no replication of viral RNA with lethal hits if the cells are infected simultaneously both with active and inactive virus.