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Biomedical subjects

R Dziarski

Publications and source records attributed to R Dziarski.

At least 55 records · Page 3Linked to original sources
PubMed1985

The role of DNA synthesis in peptidoglycan-induced generation of immunoglobulin-secreting cells in mice and humans.

The requirement for DNA synthesis in peptidoglycan (PG)-induced activation of polyclonal antibodies has been studied. Inhibition of DNA synthesis with mitomycin C or hydroxyurea at the initiation of the cultures inhibited generation of over 90% of IgM- and IgG-secreting cells in PG-stimulated mouse splenocytes and of over 99.9% of IgM-, IgG- and IgA-secreting cells in PG-stimulated human peripheral blood lymphocytes. Inhibition of DNA synthesis 2 to 4 days after initiation of PG-stimulated cultures (in both mice and humans) caused an immediate decline in the numbers of Ig-secreting cells. These results demonstrate that the magnitude of PG-induced polyclonal antibody response depends on continued DNA synthesis and proliferation of Ig-secreting cells, and indicate that IgM-, IgG- and IgA-secreting cells in polyclonal activation may be actively cycling cells.

Adult↗
PubMed1985

Comparison of in vitro and in vivo mitogenic and polyclonal antibody and autoantibody responses to peptidoglycan, LPS, protein A, PWM, PHA and Con A in normal and autoimmune mice.

We have compared the in vitro and in vivo mitogenic and polyclonal antibody (IgM-, IgG-, IgA- and IgM anti-SRBC-secreting PFC) and autoantibody (IgM anti-ssDNA-, anti-bromelin-treated [HB]- and anti-intact mouse RBC-secreting PFC) responses to peptidoglycan (PG), LPS, protein A, PWM, PHA and Con A in young (4-7 weeks) and old (7-8 months) normal (BALB/c, CBA/H, C57BL/6) and autoimmune (NZB, NZB X NZW F1, BXSB, MRL/1; old BXSB and MRL/1 were 4-5 months) mice. Our results demonstrated that: lymphocytes from young and old autoimmune mice (except old BXSB) could be further polyclonally activated in vitro by PG or LPS as well as or better than lymphocytes from young and old normal mice; lymphocytes from young or old autoimmune mice were less polyclonally activated in vitro by protein A or PWM, respectively, than lymphocytes from young or old normal mice; PG and LPS were equally effective polyclonal activators in vitro; in vivo, LPS was a stronger stimulant than PG; in vivo, LPS could induce polyclonal activation in both young and old normal and autoimmune mice, whereas, PG could only induce polyclonal activation in vivo in young and old normal mice, but did not induce further activation in young and old autoimmune mice; only some tests (anti-ssDNA and IgG PFC in vivo, and IgA and anti-HB MRBC PFC in vitro) revealed higher responses in autoimmune than in normal mice, and these higher responses were seen more often in vivo than in vitro; both autoimmune and normal mice had a high frequency of autoantibody (especially anti-ssDNA) secreting cells in polyclonal activation in vitro, whereas a high frequency of these cells in vivo was only found in autoimmune mice; in most cases in vitro, polyclonal activators did not change the frequency of autoantibody and heteroantibody secreting cells, but in vivo, both PG and LPS increased the frequency of anti-ssDNA antibody secreting cells in normal, but not in autoimmune, mice; LPS increased the in vivo, but not in vitro, frequency of cells secreting anti-HB MRBC antibodies in some strains of mice; old mice had lower mitogenic responsiveness than young mice in both autoimmune and normal strains; autoimmune mice had similar, higher or lower mitogenic responses than normal mice, depending on the strain and the age, but in most cases consistent for both B and T cell mitogens; and there was no correlation between the patterns of increased or decreased mitogenic and polyclonal antibody responses in normal and autoimmune mice.4+.

Age Factors↗
PubMed1984

Anti-immunoglobulin autoantibodies are not preferentially induced in polyclonal activation of human and mouse lymphocytes, and more anti-DNA and anti-erythrocyte autoantibodies are induced in polyclonal activation of mouse than human lymphocytes.

Using a plaque assay with immunoglobulin (Ig)-coated SRBC, we and others have previously reported that the majority of polyclonally activated mouse lymphocytes secreted antibodies that appeared to be IgM anti-IgG autoantibodies. Careful reexamination of this assay, with application of several highly purified mouse serum and myeloma IgG and IgM preparations, revealed that IgM, which was a minor contaminant of Ig preparations, rather than IgG, was responsible for the formation of these plaques. High numbers of plaques could also be detected in assays with polyclonally activated human lymphocytes, Ig-coated SRBC, and anti-Ig developing sera. Of all IgG-, IgM- or IgA-secreting cells, 40 to 100% were detected with SRBC coated with gamma-globulin or Ig of the same isotype as the isotype to which the developing serum was specific; in general, low proportions of all PFC were detected with SRBC coated with Ig of a different isotype. Studies on the sequence of events leading to the formation of plaques with Ig-sensitized SRBC (both in humans and mice) revealed that antibodies detected in these assays were not able to bind to the Ig-coated SRBC (without the presence of developing serum), and therefore were not anti-Ig autoantibodies. It is our conclusion that the plaque assays with Ig-coated SRBC represent another type of a reverse hemolytic PFC assay that detects cells secreting antibodies regardless of their specificity, and these plaques are formed due to the cross-linking by the anti-Ig developing serum of the Ig coated on SRBC and the Ig secreted by lymphocytes. Our results confirmed preferential induction of anti-DNA antibody secreting cells in mice by showing that these antibodies indeed bind to DNA coated on SRBC. In cultures of polyclonally activated human lymphocytes, anti-DNA and anti-erythrocyte autoantibody-secreting cells were over 10 to 100 times less frequent than in mice. These results, therefore, disprove the concept of preferential induction of anti-Ig autoantibodies in the polyclonal activation of mouse and human lymphocytes, and show that anti-DNA and anti-erythrocyte autoantibodies are easily induced in the polyclonal activation of mouse, but not human, lymphocytes.

Adult↗
PubMed1984

Opposing effects of xid and nu mutations on proliferative and polyclonal antibody and autoantibody responses to peptidoglycan, LPS, protein A and PWM.

We have compared the in vitro and in vivo mitogenic and polyclonal antibody (IgM-, IgG-, IgA- and anti-SRBC-secreting PFC) and autoantibody (IgM anti-ssDNA and anti-bromelin-treated mouse RBC-secreting PFC) responses to peptidoglycan (PG), LPS, protein A and PWM in homozygous xid or nu and normal mice. Our results demonstrated opposing effects of xid and nu on polyclonal B cell activation; in general, xid retarded and nu enhanced or did not change these responses. These effects, however, were greatly dependent on the in vitro or in vivo conditions of the stimulation and the type of polyclonal activator used and antibody assayed (isotype and specificity). In vitro, in xid mice, the numbers of all PFC assayed and proliferative responses were lower than in normal mice, whereas in nude mice the numbers of PFC were mostly unchanged, and proliferative responses were increased (PG, LPS) or decreased (protein A, PWM). The in vitro frequencies of autoantibody-secreting cells were similar (anti-DNA) in xid, nude and normal mice, or lower (anti-RBC) than normal in xid mice. In vivo, unstimulated xid mice had lower than normal numbers of IgM-, IgG- and autoantibody-secreting cells and higher numbers of IgA PFC, but in stimulated xid mice, the numbers of all Ig PFC were similar to normal, whereas anti-DNA and anti-RBC PFC were still depressed. The frequencies of anti-DNA and anti-RBC PFC were also lower than normal in xid mice in vivo. Nude mice in vivo had higher than normal numbers and frequencies of anti-DNA PFC and lower numbers of IgM and anti-SRBC PFC. These results indicate preferential retardation of autoantibody-secreting cells in xid mice in vivo and preferential enhancement of these cells in nude mice in vivo. Since in xid mice in vitro PG- and LPS-induced responses were similarly diminished, PG, like LPS, appears to primarily activate a late-maturing B cell subpopulation affected by the xid mutation.

Animals↗
PubMed1984

Analysis of in vitro polyclonal B cell differentiation responses to bacterial peptidoglycan and pokeweed mitogen in rheumatoid arthritis.

To gain insight into possible determinants of in vivo polyclonal B cell activation seen in rheumatoid arthritis (RA), we enumerated immunoglobulin secreting cells appearing in cultures of peripheral blood mononuclear cells that were stimulated with pokeweed mitogen (PWM) or a newly described polyclonal B cell activator, bacterial peptidoglycan. Peptidoglycan, the major constituent of the cell wall of gram positive bacteria, has properties which warrant its consideration in the pathogenesis of RA; including the ability to induce rheumatoid factor production as well as a RA like syndrome in experimental animals. RA patients as a group had similar immunoglobulin secreting cell responses in PWM stimulated cultures compared to arthritis controls and showed moderately depressed responses compared to healthy volunteers. However, their in vitro responses to peptidoglycan were markedly depressed when compared to those of both control groups. Of note, severely reduced peptidoglycan-induced responses were seen in 26 of 55 rheumatoid patients who demonstrated intact PWM-induced responses. These impaired responses to peptidoglycan were not due to (1) aberrant kinetic response; (2) shift in the dose-response pattern; (3) decreased cell survival in culture or (4) the inability of peptidoglycan to activate RA cells. Cell fractionation studies indicated that peptidoglycan reactive B cells were present in the blood of some patients but their reactivity was abrogated by suppressor T cells. These studies provide evidence of aberrant in vitro polyclonal B cell activation in patients with RA and provide a basis for further investigation of peptidoglycan as an immunopathogenetic agent in this disease.

Adult↗
PubMed1983

Staphylococcal peptidoglycan: T-cell-dependent mitogen and relatively T-cell-independent polyclonal B-cell activator of human lymphocytes.

Staphylococcal cell wall products have been widely examined as probes for dissection of in vitro human immune responses. Mitogenic and polyclonal B-cell-activating properties have been attributed to intact cell walls or the protein A constituent thereof. We now report that staphylococcal peptidoglycan (PG), the major cell wall constituent, is not only a potent mitogen but also a polyclonal B-cell activator for human peripheral blood mononuclear cells (PBM). PG-induced proliferative responses of human PBM were comparable to that observed in pokeweed mitogen-stimulated cultures. As was true for pokeweed mitogen, PG-induced proliferation required the presence of T-cell help. Cultures of human PBM with PG also resulted in B-cell differentiation as reflected by an increase in numbers of immunoglobulin-secreting cells in stimulated cultures. In contrast to the proliferative response, PG-induced B-cell differentiation was relatively T-cell independent. This point became apparent when B-cell fractions were partially depleted of excessive numbers of monocytes before culture. Also, B-cell proliferation did not appear to be a major prerequisite for PG-induced B-cell differentiation responses. These data indicate that PG is a potent T-cell-dependent mitogen and relatively T-cell-independent polyclonal B-cell activator of human lymphocytes.

B-Lymphocytes↗
PubMed1982

Studies on the mechanism of peptidoglycan- and lipopolysaccharide-induced polyclonal activation.

Peptidoglycan (PG) and lipopolysaccharide (LPS) are T cell-independent B cell mitogens and polyclonal activators in mice. The mechanism of in vitro proliferation and polyclonal activation of mouse splenocytes induced by PG from Staphylococcus aureus and LPS from Escherichia coli was further studied by using [3H]thymidine incorporation and protein A hemolytic plaque assays. Concanavalin A-generated suppressor cells suppressed both polyclonal and proliferative responses induced by PG, LPS, and pokeweed mitogen. The suppression of the proliferative responses was similar for all these mitogens, but was significantly less pronounced than the suppression of the polyclonal antibody response. Polyclonal activation induced by LPS was the most susceptible to suppression by concanavalin A-generated suppressor cells, and the suppression was significantly greater than in the PG-induced polyclonal response. Also, PG-induced polyclonal activation was not susceptible to inhibition by polymyxin B, which is an inhibitor of other B cell mitogens and polyclonal activators. For optimal generation of immunoglobulin-secreting cells, PG of LPS had to be present for at least 48 h after the initiation of the cultures. Removal of the mitogens after 4 or 24 h of incubation resulted in a suboptimal response. For effective induction of the proliferative response, the mitogens had to be present in cultures for over 24 h. Polyclonal-activating properties of staphylococcal cell wall components were also compared. PG was by far the most potent inducer of polyclonal antibodies. Teichoic acid was not active as a polyclonal activator, whereas purified cell wall and protein A were very weak inducers of polyclonal antibodies. These studies demonstrate that PG, in addition to LPS, can be a useful probe for studies on polyclonal activation.

Animals↗
PubMed1982

Preferential induction of autoantibody secretion in polyclonal activation by peptidoglycan and lipopolysaccharide. I. In vitro studies.

Peptidoglycan (PG) and lipopolysaccharide (LPS) are bacterial cell wall components that are B cell mitogens and activators of polyclonal antibodies. Using the hemolytic plaque assay and its modifications with protein A-, IgG-, or DNA-coated erythrocytes, we determined the proportions of cells that secrete antibodies specific to various autologous and heterologous antigens in PG- and LPS-stimulated cultures of mouse splenic lymphocytes. Of all PG- and LPS-activated IgM-secreting cells, 47 to 75% produced antibodies specific to mouse IgG; 2.7 to 21% produced IgM antibodies that reacted with bovine IgG; 4.4 to 17%, with single-stranded (ss) DNA; 0.18 to 5.9% with double-stranded (ds) DNA; 0.16 top 3.3%, with bromelin-treated mouse red cells; 0.006 to 0.02%, with intact mouse red cells; and 0.35 to 1.9%, with sheep red cells. A similar distribution of cells secreting these antibodies was observed in unstimulated cultures. However, the absolute numbers of cells secreting these antibodies were substantially higher in the PG- and LPS-stimulated cultures. Similar results were obtained in BALB/c, CBA/H, and C57BL/6 mice. Since these strains of mice have different H-2 types, there was no association of a single H-2 type with the ability to form hgh numbers of autoantibody-secreting cells in vitro. The production of autoantibodies closely resembled polyclonal activation of all immunoglobulin-secreting cells in terms of the kinetics and dose-response. It did not involve any substantial specific anti-PG or anti-LPS response. Further studies on the specificities of polyclonally induced antibodies confirmed the specificity of anti-mouse IgG and anti-ssDNA antibodies. However, the formation of plaques with bovine IgG- or dsDNA-sensitized red cells was due to the cross-reacting anti-mouse IgG or anti-ssDNA antibodies, respectively. These results do not support the popular hypothesis of an equal polyclonal activation of lymphocytes secreting antibodies of all different specificities. Also, if preferential activation of cells secreting rheumatoid factor and anti-ssDNA antibodies occurs in vivo, it may have important pathologic consequences.

Animals↗
PubMed1980

Modulation of mitogenic responsiveness by staphylococcal peptidoglycan.

Staphylococcal peptidoglycan can modulate in vivo and in vitro antibody responses and is a B-cell mitogen. The effect of in vivo peptidoglycan treatment on the subsequent in vitro mitogenic responsiveness of mouse splenocytes to phytohemagglutinin, concanavalin A, pokeweed mitogen, and lipopolysaccharide was studied by measuring changes in deoxyribonucleic acid synthesis. Injection of peptidoglycan caused a 100% increase in responsiveness to phytohemagglutinin and pokeweed mitogen and a 45% increase in responsiveness to concanavalin A. Responsiveness to lipopolysaccharide was decreased by 40%. Increased phytohemagglutinin and decreased lipopolysaccharide responses were not due to changes in the kinetics of the response or optimal concentrations of these mitogens. Increased responsiveness to phytohemagglutinin lasted for 2 weeks after peptidoglycan injection. Neither increased background deoxyribonucleic acid synthesis nor changes in the proportion of T cells after peptidoglycan treatment fully accounted for the changes in responsiveness to the mitogens. In vitro costimulation with peptidoglycan and phytohemagglutinin, lipopolysaccharide, concanavalin A, or pokeweed mitogen resulted in interference of the response. Cell separation experiments indicated that peptidoglycan-induced modulation of mitogenic responsiveness was mediated by B lymphocytes.

Animals↗
PubMed1980

Mitogenic responsiveness of mouse, rat and human lymphocytes to Staphylococcus aureus cell wall, teichoic acid, and peptidoglycan.

The mitogenic activity of Staphylococcus aureus peptidoglycan (PG), teichoic acid (TA) and cell wall (CW, a PG-TA complex) for mouse, rat and human lymphocytes was determined by measuring DNA synthesis. At optimal concentrations PG was the most potent mitogen, inducing maximum stimulation of mouse spleen lymphocytes on day 2 of culture, rat spleen lymphocytes on day 3, rat lymph node cells on day 2, human peripheral blood lymphocytes on day 5, and human cord blood lymphocytes on day 4. CW was less mitogenic than PG for mouse splenocytes and human peripheral and cord blood lymphocytes, with maximum stimulation occurring on days 2, 6 and 5, respectively. CW was not mitogenic for rat lymphocytes, and TA was not mitogenic for mouse, rat and human lymphocytes. At high concentrations CW and TA were cytotoxic, as indicated by markedly reduced thymidine uptake and low viability. PG was not toxic to lymphocytes. Our results suggest that TA when bound to PG can at high concentrations mask the mitogenic activity of PG and render CW cytotoxic.

Animals↗
PubMed1980

Polyclonal activation of immunoglobulin secretion in B lymphocytes induced by staphylococcal peptidoglycan.

Staphylococcal peptidoglycan (PG) is a B cell mitogen and immunomodulator in mice. The ability of PG to induce the secretion of polyclonal antibodies in murine lymphocyte cultures was studied using the protein A hemolytic plaque assay. PG was as effective as or more effective than lipopolysaccharide as an inducer of polyclonal antibodies in spleen, lymph node, and bone marrow lymphocytes. The highest numbers of immunoglobulin (Ig) secreting cells were induced in the spleen, and the lowest in the bone marrow cell cultures. All major classes of Ig (IgM, IgG, and IgA) were induced, and the maximal numbers of Ig-secreting cells were detected between days 4 and 5 of culture. The induction of Ig secretion by Pg was T cell, 2-mercaptoethanol, and to a large extent macrophage independent.

Animals↗
PubMed1979

Mitogenic activity of staphylococcal peptidoglycan.

Staphylococcus aureus peptidoglycan displayed a marked dose-dependent mitogenic activity for mouse splenocytes and human peripheral blood lymphocytes in vitro, as measured by increased [3H]thymidine incorporation. Similarly it was mitogenic for athymic nude mouse spleen cells, whereas no blastogenic effect was observed in T cell-enriched and B cell-depleted mouse lymphocyte cultures. These data demonstrate that peptidoglycan-responding cells in mouse spleen cell cultures are B lymphocytes.

Animals↗
PubMed1979

Relationships between adjuvant, immunosuppressive, and mitogenic activities of staphylococcal peptidoglycan.

Staphylococcal peptidoglycan (PG) possesses in vivo immunodulating activity and is a B-cell mitogen in mice. The effect of PG on in vitro immune response of mouse splenocytes to sheep erythrocytes (SRBC) was studied, as well as the relationships between in vivo and in vitro adjuvant, immunosuppressive, and mitogenic activities of PG in terms of dose response, time kinetics, and physical state. Particulate PG suppressed in vivo anti-SRBC response when injected in a large dose before or simultaneously with SRBC. A small dose of particulate PG given before or along with the antigen was immunostimulatory. Soluble PG was adjuvant active in both high and low doses when injected before or along with the antigen. Both PG preparations were adjuvant active for mouse splenocytes in vitro immunized with SRBC, but particulate PG was more active. Even high doses of particulate PG were not directly suppressive for the in vitro immune response. Particulate PG was also mitogenic for mouse splenocytes, and the maximum increase in [3H]thymidine incorporation was observed after 2 days of culture. Soluble PG was not mitogenic during the 5-day incubation period. These results indicate that the physical state of PG, its dose, and its time of application are important factors determining its immunomodulating and mitogenic activities, and that by changing them it is possible to dissociate the adjuvant, immunosuppressive, and mitogenic properties of PG.

Adjuvants, Immunologic↗
PubMed1978

Immunosuppressive effect of Staphylococcus aureus peptidoglycan on antibody response in mice.

Immunosuppressive effect of an adjuvant, Staphylococcus aureus peptidoglycan, on the primary IgM antibody response in mice was studied with application of the hemolytic plaque assay. Peptidoglycan suppressed the IgM response to thymus-dependent sheep erythrocyte antigen when given intravenously before immunization. The effect of peptidoglycan and erythrocytes was both time and dose dependent. For the suppression, both the delay in the antibody response and overall decreased response were responsible. Peptidoglycan did not influence background counts of antibody-forming cells. Priming with subthreshold dose of erythrocytes did not overcome the suppression, although higher responses compared to unprimed animals were observed. Peptidoglycan did not suppress antibody response to thymus-independent antigens-lipopolysaccharide or high dose of erythrocytes. It is suggested that peptidoglycan-induced immunosuppression is mediated by a presently unidentified population of helper cells-macrophages or T lymphocytes.

Animals↗