Biomedical subjects

J Cerny

Publications and source records attributed to J Cerny.

At least 109 records · Page 6Linked to original sources

PubMed1976

Interactions of murine leukemia virus (MuLV) with isolated lymphocytes. III. Alterations of splenic B and T cells in Friend virus-infected mice.

Lymphoid tissues of mice infected with murine leukemia virus (Friend) (MuLV-F) were examined for the presence of cellular markers of MuLV-F infection. The Friend virus-associated cell membrane antigen (FVMA) and the virus group-specific antigen (GSA) were detectable on cells from the spleen and, to a lesser degree, on cells from the bone-marrow. In contrast, neither FVMA nor GSA was found in cells from the thymus. Alterations in the B-cell and T-cell spleen populations of MuLV-F-infected mice were then studied. The proportion of Ig-positive cells declined from the initial 45% (in non-infected controls) to about 10% after 2 weeks of infection. A similar decline of theta-positive cells was noted. However, complement-bearing cells (EAC rosettes) declined even more rapidly and became undetectable in the second week after infection. The treatment of spleen cells from MuLV-F-infected mice with anti-FVMA serum plus complement in vitro reduced the number of detectable Ig-positive cells, specifically, whereas the number of theta-positive cells remained unchanged. Furthermore, B and T cells from spleens of infected mice were separated on an affinity column with anti-Ig antibody-coated beads. The initial cell suspension contained about 45% FVMA-positive cells, about 40% Ig-positive cells and about 40% theta-positive cells. Ig+ cells were retained on the column. The theta-positive cell fraction was collected in the eluate and contained very few FVMA-positive cells with some "null" cells. Most of the FVMA-positive cells were retained on the column, which strongly suggested that they were B cells. These results confirm the previous experiments which showed the selective infections of purified splenic B cells by MuLV-F in cultures.

Animals↗

PubMed1976

Immunosuppression by Moloney leukemia virus: lack of correlation between virus replication and the immunosuppressive effect.

Young adult mice were infected with 10(4) plaque-forming units (PFU) or Moloney murine leukemia virus M-MuLV. Two different virus preparations were used: a) M-MuLV obtained from serial passage in mice [animal passage (AP)] and b) tissue culture (TC)-grown virus harvested after three in vitro passages of the AP M-MuLV in fibroblasts. Replication of TC and AP M-MuLV in spleen cells was determined by an infectious center (IC) assay at 1 and 2 weeks after the infection. Immune responsiveness of spleen cells was evaluated in challenge with sheep red blood cells (SRBC) and subsequent enumeration of antibody plaque-forming cells (PFC). TC M-MuLV replicated faster in the spleen than did AP M-MuLV and reached about 10- to 100-fold higher titers. However, the response of anti-SRBC PFC, suppressed to the same degree in the spleens of mice infected with TC or AP virus, was from 10 to 50% of the control response. A comparison of virus replication with the anti-SRBC response in aliquots from the same spleens showed no correlation between virus IC and antibody PFC. Both TC and AP M-MuLV induced the expression of virus-specific, cell membrane antigen on spleen cells. These findings indicated a divergence between virus replication on the one hand and the immunosuppressive effect and the cell membrane alteration on the other.

Animals↗

PubMed1976

The effect of cyclophosphamide on the recovery from a local chlamydial infection. Guinea-pig inclusion conjunctivitis (GPIC).

The immune mechanism involved in the recovery from and resistance to guinea-pig inclusion conjunctivitis (GPIC) was studied. Guinea-pigs were injected with a dose of cyclophosphamide (CY) (300 mg/kg wt) that inhibits antibody synthesis. Such treatment was shown to produce a cellular depletion in the B-cell area without producing an appreciable change in the T-cell area of the spleen and lymph nodes. CY treatment markedly delayed the appearance of secretory immunoglobulin A antibody to GPIC in the tears, and other classes of antibodies to GPIC and sheep erythrocyte in the serum. Furthermore, recovery from infection was impaired and a subsequent injection of CY prolonged the duration of infection. The results indicate that B cells may play an important role in the control of this infection.

Animals↗

PubMed1976

Thymic hormone modulation of leukemogenic virus replication.

The effect of purified calf thymus extract, thymosin, on infection with murine leukemia virus (MuLV) (Rauscher) was studied in adult thymectomized BALB/c mice. The course of infection was determined by virus titer in the blood plasma, by enumeration of spleen cells replicating MuLV (i.e., infectious centers), and by the examination of cells for expression of virus-induced cell membrane antigen. Thymectomy (performed 1 week prior to the virus injection) decreased MuLV infection by all three parameters. However, administration of thymosin (500 mug, given in equal doses 2 days before and at the time of injection of virus) caused a marked increase of plasma titer of virus, as well as an increased number of spleen cells generating MuLV as compared to controls treated either with purified spleen fraction or with diluent (buffered salt solution). More than two doses of thymic extract (up to nine, given every 2 days after infection) had no further effect on plasma virus titer or number of splenic infectious centers. Furthermore, treatment of mice with either thymic or splenic extracts increased the incidence of virus related membrane antigen appearing on the surface of spleen cells, as compared to diluent-treated control animals. These results indicate that thymosin may enhance infection by or replication of murine oncornaviruses.

Animals↗

PubMed1975

Operative morbidity and mortality in renovascular disease.

There were 104 major complications (13.1%) and 34 deaths (5.9%) among 502 patients with evidence of renovascular disease who underwent 577 operative procedures. The operative mortality rate in patients with atherosclerotic renovascular disease was 9.3% vs 3.4% with fibromuscular hyperplasia. Important determinants of renovascular operative mortality are (1) cause of disease, (2) presence of coronary artery disease, (3) presence of bilateral renal functional impairment, (4) the complexity of the renal operative procedure, and (5) concurrent extrarenal surgery.

Adult↗

PubMed1975

Expression of virus-associated antigens and immune cell functions during spontaneous regression of the Friend viral murine leukemia.

Spontaneous regression and/or remission of Friend virus (FV)-induced splenic erythroblastic leukemia was observed in CD-1 mice infected with several isolates of FV. Regression of splenic tumor was accompanied by the loss of both specific FV-induced cell membrane antigen (FVMA) and virus group-specific antigens (gsa) from the spleen cells. The frequency (percentage) of immunoglobulin-positive cells (B) and thetapositive cells (T) in the spleen was markedly decreased during leukemia progression, but there was a subsequent increase during regression. The appearance of gsa-positive (gsa+) cells in peripheral blood correlated well with the early progressive and regressive phase of leukemia (up to 7 weeks after infection). Later, the presence of these cells became unpredictable in regard to status of disease. Gsa+ blood cells reappeared in most mice with regressed splenic tumors, suggesting persistence of the virus complex in the animals. Antibody responsiveness as determined by the numbers of hemolytic plaque-forming cells, PFC, after a single immunization with sheep red blood cells (SRBC), was suppressed in leukemia progression and recovered, spontaneously, during regression of leukemia. However, hemolytic PFC elicited by antigen in both progressors and regressors expressed the specific virus-induced membrane antigen, FVMA, detectable by the PFC-inhibition test with specific antiserum and complement. Recovery of immunological responsiveness also included the spontaneous appearance of virus-neutralizing antibody to FV. However, this was not paralleled by the appearance of antibody to FVMA. Traces of anti-FVMA antibody activity were occasionally detectable in serum of both progressors and regressors and did not correlate with virus neutralization, in individual mice; This may explain the susceptibility of regressors to secondary relapse and to reinfection.

Animals↗

PubMed1975

T cell products activating stem cells: further studies on the origin and action of the factor(s).

We studied the capacity of bone marrow hemopoietic stem cells to form colonies (colony forming units, CFU) in the spleens of irradiated recipient mice following incubation of the cells with T cell-derived mediators in short-term culture in vitro. The mediators were a) stem cell-activating factor (SAF) present in crude form in the supernatant from phytohemagglutinin (PHA); stimulated lymphocytes, and b) immunoenhancing factor (IEF) obtained in partially purified form from the supernatant of antigen-stimulated lymphocytes and characterized by its ability to enhance antibody formation in vitro. Both SAF and IEF increased the number of CFU in the cultured bone marrow cell suspension. However, only SAF, and not IEF, significantly stimulated DNA synthesis in the cultured cells, Furhter more, SAF appears to activate CFU in vitro, rather than merely to promote the survival of active CFU stem cells. Experiments with SAF and bone marrow from different strains of mice indicated that the biologic activity was not restricted by K and Ia regions of H complex.

Animals↗

PubMed1975

Specific susceptibility of sensitized (memory) B cells to suppression and antigenic alteration by murine leukemia virus.

Mice infected with murine oncogenic RNA viruses, either Friend virus (FV) or Moloney leukemia virus (MuLV-M) reacted well to a primary immunization with antigen(s) of Vibrio cholerae; both the kinetics and magnitude of the direct (IgM) primary vibriolytic antibody plaque forming cell (PFC) response in the spleen was the same as in non-infected control mice. In contrast, the anamnestic PFC (IgM) response of mice preimmunized with cholera and later (2 to 9 months following priming) infected with either FV or MuLV-M, before the secondary challenge, was inhibited 90% or more when compared to the anamnestic response of controls. Hemolytic PFC response to a single (primary) immunization with sheep red blood cells (sRBC, an antigen to which laboratory mice have a natural immune background) was suppressed by infection with both viruses in a manner similar to the suppression of the secondary vibiolytic response. The suppressive effect of FV, and the lack of it, on these different immune responses was correlated with the appearance of FV-induced cell membrane antigen, FVMA, on respective individual PFC from the spleen. FVMA was detected by inhibition of PFC in the presence of specific antiserum, anti-FVMA, and complement (C). In particular, about 80% of the FV-infected mice with an anamnestic response to a secondary challenge with cholera antigen had a significant decline in the proportion of PFC (33% or more) following incubation with anti-FVMA plus C. A similar degree of inhibition was found with hemolytic (anti-sRBC) PFC from FV-infected mice. In contrast, primary vibriolytic PFC from FV-infected mice were not inhibited by anti-FVMA, i.e., they did not carry the virus-induced antigen. These results indicate absolute correlation between viral suppression of a given clone of immunocompetent cells, and antigenic alteration of individual antibody-forming cells due to the virus-infection. Furthermore, the absence of both functional inhibition and virus-induced antigen(s) in the primary immunocompetent cells and the presence of both these virus-related functions in the memory cells (either experimentally sensitized cholera memory cells or naturally sensitized sRBC memory cells) strongly suggested that the latter are selectively susceptible to oncornavirus.

Animals↗

PubMed1975

Immunosuppression by spleen cells from Moloney leukemia. Comparison of the suppressive effect on antibody response and on mitogen-induced response.

The inhibitory effect of cells from leukemic spleens on the immune functions of normal lymphocytes was studied. Suppressor cells were obtained as the nonadherent fraction (NA) from splenic tumors of mice infected with MuLV-Moloney. This fraction (NA MuLV- M) contained less than 10% membrane Ig-positive (Ig+) cells, 45 to 60% theta-positive cells (theta+) and 40 to 50% naught cells (theta-, Ig-). Similarly prepared fractions from normal control spleens (NAc) containing 75 to 90% theta+cells and less than 10% Ig+ and naught cells were utilized in control cultures. Addition of the NA MuLV- M cells into cultures (Marbrook system) of normal spleen cells with sheep red blood cells suppressed the specific antibody response determined by the number of hemolytic plaque forming cells (PFC). The PFC response was significantly suppressed at a suppressor cell to responder cell ratio of 1:100, and was completely abolished at a ratio of 1:10 or higher. The control NAc fraction showed some inhibitory effect only at high suppressor to responder ratios (1:2 or 1:1). In contrast, the suppressive effect of NAMuLV-M on mitogen-induced 3H-thymidine incorporation in normal B and T cells was much weaker. Very little, if any, suppression occurred at the ratio of 1:100 or 1:10, however, about 50% decrease in DNA synthesis was observed at the ratio 1:2 or 1:1. On the basis of this differential suppressive effect, it is suggested that leukemic spleen cells can suppress the function of immunocompetent cells by more than one mechanism.

Animals↗

PubMed1974