Inhibition of inositol kinase B controls acute and chronic graft-versus-host disease.

T-cell activation releases inositol 1,4,5-trisphosphate (IP3), inducing cytoplasmic calcium (Ca2+) influx. In turn, inositol 1,4,5-trisphosphate 3-kinase B (Itpkb) phosphorylates IP3 to negatively regulate and thereby tightly control Ca2+ fluxes that are essential for mature T-cell activation and differentiation and protection from cell death. Itpkb pathway inhibition increases intracellular Ca2+, induces apoptosis of activated T cells, and can control T-cell-mediated autoimmunity. In this study, we employed genetic and pharmacological approaches to inhibit Itpkb signaling as a means of controlling graft-versus-host disease (GVHD). Murine-induced, Itpkb-deleted (Itpkb-/-) T cells attenuated acute GVHD in 2 models without eliminating A20-luciferase B-cell lymphoma graft-versus-leukemia (GVL). A highly potent, selective inhibitor, GNF362, ameliorated acute GVHD without impairing GVL against 2 acute myeloid leukemia lines (MLL-AF9-eGFP and C1498-luciferase). Compared with FK506, GNF362 more selectively deleted donor alloreactive vs nominal antigen-responsive T cells. Consistent with these data and as compared with FK506, GNF362 had favorable acute GVHD and GVL properties against MLL-AF9-eGFP cells. In chronic GVHD preclinical models that have a pathophysiology distinct from acute GVHD, Itpkb-/- donor T cells reduced active chronic GVHD in a multiorgan system model of bronchiolitis obliterans (BO), driven by germinal center reactions and resulting in target organ fibrosis. GNF362 treatment reduced active chronic GVHD in both BO and scleroderma models. Thus, intact Itpkb signaling is essential to drive acute GVHD pathogenesis and sustain active chronic GVHD, pointing toward a novel clinical application to prevent acute or treat chronic GVHD.

Glutathione Depletion Is Linked with Th2 Polarization in Mice with a Retrovirus-Induced Immunodeficiency Syndrome, Murine AIDS: Role of Proglutathione Molecules as Immunotherapeutics.

UNLABELLED: Injection of the LP-BM5 murine leukemia virus into mice causes murine AIDS, a disease characterized by many dysfunctions of immunocompetent cells. To establish whether the disease is characterized by glutathione imbalance, reduced glutathione (GSH) and cysteine were quantified in different organs. A marked redox imbalance, consisting of GSH and/or cysteine depletion, was found in the lymphoid organs, such as the spleen and lymph nodes. Moreover, a significant decrease in cysteine and GSH levels in the pancreas and brain, respectively, was measured at 5 weeks postinfection. The Th2 immune response was predominant at all times investigated, as revealed by the expression of Th1/Th2 cytokines. Furthermore, investigation of the activation status of peritoneal macrophages showed that the expression of genetic markers of alternative activation, namely, Fizz1, Ym1, and Arginase1, was induced. Conversely, expression of inducible nitric oxide synthase, a marker of classical activation of macrophages, was detected only when Th1 cytokines were expressed at high levels. In vitro studies revealed that during the very early phases of infection, GSH depletion and the downregulation of interleukin-12 (IL-12) p40 mRNA were correlated with the dose of LP-BM5 used to infect the macrophages. Treatment of LP-BM5-infected mice with N-(N-acetyl-l-cysteinyl)-S-acetylcysteamine (I-152), an N-acetyl-cysteine supplier, restored GSH/cysteine levels in the organs, reduced the expression of alternatively activated macrophage markers, and increased the level of gamma interferon production, while it decreased the levels of Th2 cytokines, such as IL-4 and IL-5. Our findings thus establish a link between GSH deficiency and Th1/Th2 disequilibrium in LP-BM5 infection and indicate that I-152 can be used to restore the GSH level and a balanced Th1/Th2 response in infected mice. IMPORTANCE: The first report of an association between Th2 polarization and alteration of the redox state in LP-BM5 infection is presented. Moreover, it provides evidence that LP-BM5 infection causes a decrease in the thiol content of peritoneal macrophages, which can influence IL-12 production. The restoration of GSH levels by GSH-replenishing molecules can represent a new therapeutic avenue to fight this retroviral infection, as it reestablishes the Th1/Th2 balance. Immunotherapy based on the use of pro-GSH molecules would permit LP-BM5 infection and probably all those viral infections characterized by GSH deficiency and a Th1/Th2 imbalance to be more effectively combated.

Expanded regulatory T cells in chronically friend retrovirus-infected mice suppress immunity to a murine cytomegalovirus superinfection.

It is still unclear whether expanded and activated regulatory T cells (Tregs) in chronic viral infections can influence primary immune responses against superinfections with unrelated viruses. Expanded Tregs found in the spleens of chronically Friend virus (FV)-infected mice decreased murine cytomegalovirus (mCMV)-specific CD8(+) T cell responses during acute mCMV superinfection. This suppression of mCMV-specific T cell immunity was found only in organs with FV-induced Treg expansion. Surprisingly, acute mCMV infection itself did not expand or activate Tregs.

Host genetic control of recovery from Friend leukemia virus-induced splenomegaly: mapping of a gene within the major histocompatability complex.

The influence of the major mouse histocompatibility gene complex (H-2) on the response of mice to Friend leukemia virus was studied in F(1) congenic mice differing only at genes within the H-2 complex. F(1) mice which were H-2(b/b) had a high incidence of recovery from splenomegaly compared to H-2(b/d) or H-2(b/a) mice. In mice with recombinations within the H-2 complex a gene (designated RFV-1), responsible for the Friend virus recovery effect, was found to map near or within the D region of serologically detectable transplantation antigens. Because the incidence of recovery was much higher in F(1)H-2(b/b) mice than in parental H-2(b/b) mice, other non-H-2 host genetic factors also appear to be important to expression of recovery in H-2(b/b) F(1) mice. The mechanisms of action of these genes remain unknown.

Influence of the murine MHC (H-2) on Friend leukemia virus-induced immunosuppression.

Friend murine leukemia virus complex (FV)-induced immunosuppression was studied by assaying splenic anti-SRBC PFC responses and plasma antibody titers in mice at various times after FV inoculation. Genes located within the H-2 complex were found to influence resistance to FV-induced immunosuppression. Near normal responses were observed in mice having the H-2a/b or H-2b/b genotype, whereas mice having the H-2a/a genotype were suppressed. This H-2 effect was observed not only in mice having heterozygous C57BL/10 X A background genes, including Rfv-3r/s, but also was apparent in mice having homozygous A-strain background genes, including Rfv-3s/s. Therefore, the Rfv-3 gene did not appear to convey resistance to FV-induced immunosuppression. The suppression in susceptible H-2a/a mice was characterized by a partial suppression of the IgM response and a profound suppression of both the primary and secondary IgG responses. Neither splenomegaly nor viremia alone appeared to be sufficient for the induction or maintenance of the immunosuppression. The mechanism of suppression was unclear, but both B lymphocyte and T lymphocyte functions appeared to be altered.

Retrovirus-induced feline pure red cell aplasia. Hematopoietic progenitors are infected with feline leukemia virus and erythroid burst-forming cells are uniquely sensitive to heterologous complement.

Feline leukemia virus subgroup C/Sarma (FeLV-C) induces pure red cell aplasia (PRCA) in cats. Just before the onset of anemia, erythroid colony-forming cells (CFU-E) become undetectable in marrow culture, yet normal frequencies of erythroid burst-forming cells (BFU-E)- and granulocyte-macrophage colony-forming cells (CFU-GM) persist. To determine if erythroid progenitors were uniquely infected with retrovirus, marrow mononuclear cells from cats viremic with FeLV-C were labeled with monoclonal antibodies to gp70 and then analyzed with a fluorescence-activated cell sorter. Both erythroid and granulocyte-macrophage progenitors were among cells sorting positively, suggesting that infection of BFU-E alone did not result in PRCA. The results were confirmed by complement (C') lysis studies using baby rabbit or guinea pig sera as sources of C'. These studies also suggested that BFU-E from cats with PRCA were unusually sensitive to C' alone, without the addition of antibody. In further studies, we demonstrated that C' activation was via the classical pathway and that C' sensitivity was unique to BFU-E and not a property of CFU-E, CFU-GM, or progenitors that were capable of giving rise to BFU-E in suspension culture. As BFU-E from cats viremic with FeLV-A/Glasgow-1 or the Rickard strain of feline leukemia virus were not sensitive to C', this finding may relate to the pathogenesis of feline PRCA. We hypothesize that, in cats viremic with FeLV-C, the abnormal C' sensitivity of BFU-E leads to the absence of CFU-E and anemia.

LP-BM5 virus-infected mice produce activating autoantibodies to the AMPA receptor.

Autoantibodies to alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors may contribute to chronic hyperexcitability syndromes and neurodegeneration, but their origin is unclear. We examined LP-BM5 murine leukemia virus-infected mice, which manifest excitotoxic brain lesions and hypergammaglobulinemia, for the presence of AMPA-receptor Ab's. Endogenous IgG accumulated upon neurons in the neocortex and caudate/putamen of infected mice and interacted with native and recombinant AMPA-receptor subunits with the following relative abundance: GluR3 > or = GluR1 > GluR2 = GluR4, as determined by immunoprecipitation. In a radioligand assay, IgG preparations from infected mice specifically inhibited [(3)H]AMPA binding to receptors in brain homogenates, an activity that was lost after preadsorbing the IgG preparation to immobilized LP-BM5 virus. These IgGs also evoked currents when applied to hippocampal pyramidal neurons or to damaged cerebellar granule neurons. These currents could be blocked using any of several AMPA receptor antagonists. Thus, anti-AMPA-receptor Ab's can be produced as the result of a virus infection, in part through molecular mimicry. These Ab's may alter neuronal signaling and contribute to the neurodegeneration observed in these mice, actions that may be curtailed by the use of AMPA-receptor antagonists.

Reproducible chromosome changes of polycyclic hydrocarbon-induced rat leukemia: incidence and chromosome banding pattern.

Statistical analysis of 361 cases of primary leukemia induced in outbred Long-Evans and Sprague-Dawley rats by 7,12-dimethylbenz[a]anthracene (DMBA) and 7,8,12-trimethylbenz[a]anthracene (TMBA) showed that the incidence of trisomy of chromosome No. 2 was significantly lower with TMBA (17.8%) than with DMBA (29.3%). This tendency was reproducible in both sexes. Another characteristic chromosome abnormality, long No. 2, was found in 10 cases (2.8%). Quinacrine fluorescence analysis revealed that cells with No. 2 trisomy or either of two types of long No. 2 had total and partial No. 2 trisomy, respectively. Other chromosome members of cells with long No. 2, as well as the chromosomes of cells with typical No. 2 trisomy and "normal diploid" leukemia cells, revealed no band abnormality. The phenotype of No. 2 trisomy, severe anemia of the hosts reported in DMBA-induced leukemias, was also noted in leukemias with TMBA-induced No. 2 trisomy but not in leukemias with long No. 2.

Immunotherapy of murine leukemia. V. Protection against Friend leukemia virus-induced immune complex glomerulonephritis by passive serum therapy.

The development of immune complex glomerulonephritis in DBA/2 mice infected with Friend murine leukemia virus (F-MuLV) was compared with that in mice protected against virus-induced disease by administration of chimpanzee anti-F-MuLV antiserum (CaF-MuLV). Morphologic analysis of glomeruli from viremic (infected) normal chimpanzee serum-treated animals revealed significant renal disease within 2 weeks following virus inoculation, with glomerular immune complex deposits and C-type viral particles seen by electron microscopy. Localization of F-MuLV envelope and core antigens (gp71 and p30, respectively) was also detected by immunofluorescence, as was murine IgG and C3. However, age-matched DBA/2 mice treated with CaF-MuLV antiserum alone or following F-MuLV inoculation showed no evidence of systemic disease and neither localization of F-MuLV antigens nor detectable virus particles. These data indicate that in addition to erythroleukemia, F-MuLV infection results in severe immune complex glomerulonephritis and that passive immunotherapy can protect susceptible mice from both aspects of viral pathogenesis.

Low incidence of gross leukemia virus-induced lymphomas in spontaneously hypertensive rats with thymic dysfunction.

We compared the incidence of lymphomas induced by Gross leukemia virus (GLV) between spontaneously hypertensive rats (SHR) with a congenital T-cell depression related to thymic dysfunction and normal Wistar rats, the original strain of SHR. Of 20 SHR given neonatal injections of GLV, only 3 (15%) died with thymic lymphomas about 100 days after the virus infection. In contrast, 27 of 28 Wistar rats (96%) developed lymphomas of mostly thymic origin. The 3 lymphomas derived from the SHR bore only a Thy 1.1 antigen, whereas most of the lymphomas derived from Wistar rats carried not only a Thy 1.1 antigen but also a guinea pig red blood cell rosette receptor and a T (W3/13) antigen. Grafts of 1-week-old male Wistar thymus into the neonatal female SHR promoted a differentiation of thymocytes and markedly increased the incidence of the lymphomas which were positive for a guinea pig red blood cell rosette receptor and a T-antigen; grafts of 1-week-old SHR thymus, however, failed to do this. These results suggest that the low incidence of GLV-induced lymphomas in SHR may correlate closely with the absence or decreased numbers of the rosette-forming thymocytes which are presumably the target cells for GLV.

Development of pulmonary leukostasis in experimental myelocytic leukemia in the Brown-Norway rat.

The pathogenesis of pulmonary leukostasis in leukemia was studied in a rat model by investigating the course of its development. Leukemia was induced by inoculating rats with leukemic cells. The earliest stage of leukostasis was found from day 14 onward, when leukemic cells appeared in the peripheral blood, and was characterized by accumulation of leukemic cells at the capillary level. Simultaneous with the increase of leukemic cell concentrations in the peripheral blood, accumulation in capillaries increased gradually over a period of several days. This was accompanied by increasing severity of tachypnea. Shortly before death, aggregates consisting almost solely of leukemic cells were found in medium-sized blood vessels. This stage was rapidly followed by the end-stage, characterized by complete obstruction of the lung vasculature--including the largest arteries and veins--by leukemic cell aggregates, giving rise to extensive hemorrhages and edema. The end-stage was considered to be the cause of death, which occurred 18-26 days after the inoculation. The histological and ultrastructural findings in this study suggest that besides the size and stiffness of individual leukemic cells, interactions not only between leukemic cells, but also between leukemic cells and the endothelium play a role in the pathogenesis of pulmonary leukostasis.

CD5+ B cells from bovine leukemia virus infected cows are activated cycling cells responsive to interleukin 2.

Most of the B cells from bovine leukemia virus (BLV) infected cows in persistent lymphocytosis (PL) were known to express the CD5 T-cell marker but it was not known whether this peculiar membrane phenotype relates to an activation state. It was demonstrated that these B cells were also flagged by two other membrane markers normally borne by cells belonging to the myeloid lineage (namely CD11b and CD11c). Moreover, cell cycle analysis illustrated that a significant percentage of these B cells (greater than 15%) left their resting (G0/G1) status and progressed through the cell cycle. In addition, T-cell-depleted peripheral blood mononuclear cells from animals in PL were shown to proliferate in response to a IL-2-containing supernatant (MLA 144). These results indicate that the CD5+ B cells from BLV-infected cows in PL are activated cells.

Involvement of the complement system in the pathogenesis of pulmonary leukostasis in experimental myelocytic leukemia.

The role of the complement system in the pathogenesis of pulmonary leukostasis in myelocytic leukemia was studied in a rat model. Acute myelocytic leukemia was induced in six Brown-Norway rats, and complement levels were assayed during the course of the disease. Whole complement activity (CH50) and hemolytic activity of C1q, C3, and C4 decreased from day 16 after induction of the leukemia, when the rats developed pulmonary leukostasis. In addition, local complement activation was established in the lung vessels by immunofluorescence microscopy in advanced stages of pulmonary leukostasis. Finally, following systemic activation of the complement system by injection of cobra venom factor (CVF), leukemic rats (n = 6) died of pulmonary leukostasis 4.5 days earlier than did leukemic controls (n = 6). These findings suggest that, in acute myelocytic leukemia in Brown-Norway rats, pulmonary leukostasis is induced by activation of the complement system. This finding could lead to new modes of treatment for a life-threatening complication of leukemia.

Murine leukemia virus induced central nervous system diseases.

The ts1 mutant of Moloney murine leukemia virus TB (MoMuLV-TB) causes a degenerative neurologic and immunologic disease in mice characterized by development of spongiform encephalomyelopathy that results in hind-limb paralysis, marked thymic atrophy associated with immunodeficiency, and generalized body wasting. T cells, particularly CD4+ helper T cells, play a key role in the pathogenesis of the disease induced by ts1. Therefore, ts1 is unique among the described murine retroviruses in its ability to afflict both the central nervous system (CNS) and the T-cell compartment of the immune system in the same host. This particular ability to cause degenerative diseases involving both the CNS and immune system is shared by the lentiviruses responsible for development of the acquired immunodeficiency syndromes of humans and macaques. Our goal has been to elucidate the specific cellular and molecular mechanisms that underlie this neuro- and immunopathogenicity of ts1. We have previously reported that the primary neuropathogenic determinant of ts1 maps to a single amino acid substitution, Val-25-Ile, in the precursor envelope protein gPr80env. Further, at the restrictive temperature, the Val-25-Ile substitution did not prevent oligomerization of the gPr80env proteins; however, the structure of the oligomer was incompetent for transport from the ER to the Golgi. These findings suggest that the cytopathic effect of ts1 in neural cells might be due to accumulation of the gPr80env oligomers in the ER. Since glial cells are targets of ts1 infection in vivo, primary astrocytic cultures were established and the cytopathic effect of ts1 and MoMuLV-TB on these cells assessed. Both viruses replicate well in astrocytes and their replication is cytopathic, albeit to different degrees. The ts1 mutant appears to produce greater cell killing than the wild-type virus. Furthermore, it was found that the rate of processing of gPr80env of ts1 in astrocytes is slower than that of MoMuLV-TB. Therefore, the inefficient transport and processing of gPr80env of ts1 appears to correlate with its cytopathic effect in these cells. Electron microscopic studies of the ts1-infected astrocytes revealed large numbers of aberrant particles in the ER. The in vitro cytopathic effect of ts1 on astrocytes may reflect what happens in vivo. An indirect mechanism of neuronal-cell killing by ts1 is proposed.

3'-Azido-3'-deoxythymidine ameliorates the thrombocytopenia observed in a murine model of AIDS.

3'-Azido-3'-deoxythymidine (AZT) is used in the management of acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC). The myelotoxic actions of AZT are well known but its effect on platelets is not clear. We studied the effect of AZT at 1 and 2.5 mg/ml in drinking water on platelets in a murine model of AIDS. Three stages of the disease were examined, as determined by the serum IgM levels and other physical features. As early as 15 days after the initiation of drug treatment, AZT was found to significantly increase platelet production. To ascertain that this activity was authentic, a further study was carried out using uninfected mice. Mice were given AZT at both doses for 15 and 30 days. All mice on AZT had significantly increased numbers of platelets. These increases were dose and time dependent. AZT is therefore a potent inducer of thrombocytosis and may be a potential candidate in the treatment of thrombocytopenia in AIDS.

[Mechanisms of action of LB-plaferon and fenovin in the cases of Rausche virus leukemia].

The aim of our investigation was to examine the mechanisms of protective features of plaferon LB and fenovit in mice infected with Rausche virus. It was found that in erythroblasts from peripheral blood and spleen, which appeared 12-14 days after infection, the highest percent of determined virus antigens was approximately 47% (range 35,5 to 58,4) which was followed by decrease of the concentration of virus antigens (between 5-12%) in following days and increase of uninfected cells as a result of division of non-contaminated erythroblasts. Mechanism of action of plaferon LB and fenovit was manifested in the reconstitution of mechanisms of apoptosis among erythroblasts, which did not contain synthesized Rausche virus. Impairment of functional activity and antivirus resistance of macrophagal phagocytes are playing an important role not only in the pathogenesis of murine viral leukemia caused by Rausche virus, but also during human leukemia. Correction of functional status of above -- mentioned diseases using plaferon LB and fenovit is presenting as a new and prospective way.

Remission of FeLV-associated lymphosarcoma and persistent viral infection after extracorporeal immunoadsorption of plasma using staphylococcal protein A columns: details of immune response.

Sixteen feline leukemia virus (FeLV)-infected cats with lymphosarcoma (LSA) were treated by extracorporeal immunoadsorption using staphylococcal protein A columns in order to remove immunoglobulin G (IgG) and circulating immune complexes (CIC) from plasma. Complete viral clearance and long-lasting tumor regression were achieved in nine of the cats and tumor regression without virus clearance was observed in two other cats. Since LSA cats rarely go into spontaneous remission, and since other forms of therapy are ineffective, these cats offered a unique system for analyzing details of the immune response to LSA and FeLV as they are cleared. Immunological parameters associated with the FeLV and LSA responses were assessed in detail in three responder cats and three nonresponders during the treatment and follow-up periods. Two serological parameters that always correlated with complete clearance of LSA were development of precipitating antibodies against FeLV-C gp70 and development of cytotoxic antibodies that kill cultured FL74 LSA cells in the presence of complement. The precipitating antibodies were detected prior to the clearance of LSA and prior to the detection of free cytotoxic antibodies. One serological parameter that always correlated with complete clearance of. FeLV was development of free antibodies to FeLV-AB gp70. Quantitative levels of FeLV-specific CIC and feline oncornavirus-associated cell membrane antigen (FOCMA)-specific CIC correlated well with fluctuating levels of the corresponding antigens and antibodies. These results suggest that the staphylococcal protein A treatment columns remove CIC "blocking factors" directly or indirectly and thereby stimulate existing antibody responses. These antibodies mediate clearance of FeLV and LSA.

Modulation of immunity in patients with autoimmune disease and cancer treated by extracorporeal immunoadsorption with PROSORBA columns.

Extensive animal studies and clinical observations support an immunosuppressive role for certain antibodies and circulating immune complexes (CIC) in malignant and autoimmune diseases. Investigators have attempted to correct or modulate dysfunction by removal of antibodies or CIC from plasma. Extra-corporeal immunoadsorption of plasma over columns containing a silica matrix and covalently attached highly purified staphylococcal protein A (PROSORBA column) is a procedure that specifically removes those plasma components by the interaction of protein A with the Fc region of IgG. The interaction of CIC with the Fc receptor on protein A has three specific results. First, there is direct removal of immunosuppressive CIC from the circulation. Studies of CIC-mediated immunosuppression in experimental systems have shown dose-response relationships over wide ranges of CIC concentrations. Thus, removal of CIC relative to the IgG antibody may be expected to exert some stimulation of the immune system. Second, the complement system is activated. Elevated levels of C3a, C4a, and C5a are observed in patients' circulating plasma after PROSORBA treatment. These levels peak one to three hours post-perfusion and are near normal levels by six hours post-perfusion. These complement components are stimulators of growth and activity of immune cells. In addition, by binding to CIC they stimulate clearance of CIC by the reticuloendothelial system. Thus, treatments may induce removal of more CIC than could be anticipated by the binding capacity of treatment columns. Third, antibody is released from CIC. Interaction of CIC with bound protein A with or without the aid of activated complement components leads to liberation of free antibody. Depending upon other factors, eg, amount of circulating antigen and/or unbound IgG, either free antibody or CIC containing more antibody relative to antigen (or both) may be infused into patients with the posttreatment plasma. Such CIC function as immune stimulators rather than suppressors of immune cell activity. The consequences of the treatments are summarized as follows. Stimulation of immune cellular activity is seen one to three hours posttreatment. During the first one to three treatments, cells of the granulocyte/macrophage series show the greatest increase. During and after treatments 2 to 4, lymphocytes show the greatest increase. At this point, increased blastogenic response to mitogens is observed along with an increase in the T helper/suppressor cell ratio.(ABSTRACT TRUNCATED AT 400 WORDS)

Leukaemia and anaemia in AKR/O mice. II. Role of the spleen as an erythropoietic organ during leukaemia development.

In order to study the role of the spleen in erythropoiesis during AKR/O leukaemogenesis, we have cultured bone marrow and spleen erythroid colony-forming units (CFU-E) and burst-forming units (BFU-E) from AKR/O mice (n = 40) with leukemia of varying severity and type of manifestation. Mice with leukaemia/lymphoma had reduced concentrations of bone marrow CFU-E and BFU-E as compared to healthy, age-matched AKR/O mice. The spleen content of CFU-E was increased, and highest in mice with a spleen size between 500 and 1000 mg. The largest spleens had a somewhat lower CFU-E content. Mice with the highest spleen CFU-E content most often had a normal PCV; however, 4/7 had a normal bone marrow CFU-E concentration. During AKR/O leukaemogenesis with development of spleen enlargement, the spleen may act as an erythropoietic organ, and contribute to maintaining a normal PCV. This may be a temporary ability which is reduced or lost with further progress of the disease.

Antiviral activities of 4'-(9-acridinylamino)-methanesulfon-M-aniside (SN11841).

SN11841 [4'-(9-acridinylamino)-methanesulfon-m-aniside] is an antitumor compound discovered by B.F. Cain. The LD50 for BALB/c mice with single intraperitoneal dosage is approximately 25 mg/kg. RLV-(Rauscher leukemia virus)-induced splenomegaly, a disease indicator in BALB/c mice, is inhibited at SN11841 doses not causing acute mortality. The life span of RLV-infected mice increases at some SN11841 doses. SN11841 does not have direct, or virolytic effects on RLV under conditions approximating those of antiviral effectiveness. SN11841 is cytotoxic for cells in tissue culture, as measured by inhibition of growth rate or vital dye uptake. At nontoxic concentrations SN11841 has no effect on RLV infectivity for murine cells, as determined by XC-cell induced syncytium formation. SN11841 has antiviral activity against vaccinia virus in tissue culture but is inactive against herpes simplex (Type 1), vesicular stomatitis, encephalomyocarditis, or reoviruses. SN11841 apparently does not act by inducing interferon. SN11841 is chemically labile, particularly in the presence of sulfhydryl compounds, but the degradation products resulting from prolonged storage in media are neither cytotoxic nor antiviral.