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The article presents a list of forthcoming research papers related to immunology. They include "DNA and its cationic lipid complexes induce CpG motif-dependent activation of murine dendritic cells," "Mature dendritic cells pulsed with exosomes stimulate efficient cytotoxic T lymphocyte responses and antitumor immunity," and "Involvement of IL-10 in exhaustion of myeloid dendritic cells and rescue by CD40 stimulation."

We report the complete sequence of a cyanogen bromide fragment of a human δ chain (En). Its interest lies in the fact that it contains the peptide joining the Vδ to the Cδ1 region. The presented sequence is compared with the homologous region of other human heavy chain classes and subclasses. The possibility that human 6 chains and other human heavy chains have in their chromosornal DNA a short J sequence, is discussed. [ABSTRACT FROM AUTHOR]

Summary: Bacterial DNA contains CpG oligonucleotide (ODN) motifs to trigger innate immune responses through the endosomal receptor Toll‐like receptor 9 (TLR9). One of the cell surface receptors to capture and deliver microbial DNA to intracellular TLR9 is the C‐type lectin molecule DEC‐205 through its N‐terminal C‐type lectin‐like domain (CTLD). CD93 is a cell surface protein and member of the lectin group XIV with a CTLD. We hypothesized that CD93 could interact with CpG motifs, and possibly serve as a novel receptor to deliver bacterial DNA to endosomal TLR9. Using ELISA and tryptophan fluorescence binding studies we observed that the soluble histidine‐tagged CD93‐CTLD was specifically binding to CpG ODN and bacterial DNA. Moreover, we found that CpG ODN could bind to CD93‐expressing IMR32 neuroblastoma cells and induced more robust interleukin‐6 secretion when compared with mock‐transfected IMR32 control cells. Our data argue for a possible contribution of CD93 to control cell responsiveness to bacterial DNA in a manner reminiscent of DEC‐205. We postulate that CD93 may act as a receptor at plasma membrane for DNA or CpG ODN and to grant delivery to endosomal TLR9. [ABSTRACT FROM AUTHOR]

Interleukin (IL)-5 induces CD38-activated splenic B cells to differentiate into immunoglobulin M-secreting cells and undergo µ to γ1 class switch recombination (CSR) at the DNA level, resulting in immunoglobulin G1 (IgG1) production. Interestingly, IL-4, a well-known IgG1-inducing factor does not induce immunoglobulin production or µ to γ1 CSR in CD38-activated B cells. In the present study, we implemented complementary DNA microarrays to investigate the contribution of IL-5-induced gene expression in CD38-stimulated B cells to immunoglobulin-secreting cell differentiation and µ to γ1 CSR. IL-5 and IL-4 stimulation of CD38-activated B cells induced the expression of 418 and 289 genes, respectively, that consisted of several clusters. Surprisingly, IL-5-inducible 78 genes were redundantly regulated by IL-4. IL-5 and IL-4 also suppressed the gene expression of 319 and 325 genes, respectively, 97 of which were overlapped. Genes critically regulated by IL-5 include immunoglobulin-related genes such as J chain and immunoglobulinκ, and genes involved in B-cell maturation such as BCL6, activation-induced cytidine deaminase (Aid) and B lymphocyte-induced maturation protein-1 (Blimp-1) and tend to be induced slowly after IL-5 stimulation. Intriguingly, among genes, the retroviral induction of Blimp-1 and Aid in CD38-activated B cells could induce IL-4-dependent maturation to Syndecan-1+ antibody-secreting cells and µ to γ1 CSR, respectively, in CD38-activated B cells. Taken together, preferential Aid and Blimp-1 expression plays a critical role in IL-5-induced immunoglobulin-secreting cell differentiation and µ to γ1 CSR in CD38-activated B cells. [ABSTRACT FROM AUTHOR]

We investigated the protein-binding sites in a DNAse I hypersensitive site associated withbcl-2 gene expression in human B cells. We mapped this hypersensitive site to the coding sequence of exon 2 of thebcl-2 gene in the bcl-2-expressing REH B-cell line. Electrophoretic mobility shift assays (EMSAs) with extracts from REH cells revealed three previously unrecognized B-Myb-binding sites in this sequence. The protein was identified as B-Myb by using a specific antibody and EMSAs. Accordingly, the levels of B-Myb and bcl-2 proteins, and of Myb EMSA activity, were correlated over a wide range of cell lines, representing different stages of B-cell development. Transfection of REH cells with antisense B-mybdown-regulated EMSA activity and the level of bcl-2, and led to the apoptosis of REH cells. Transfection of the bcl-2-non-expressing RPMI 8226 cell line with a B-Myb expression vector induced B-Myb EMSA activity and the expression of bcl-2. Reporter assays indicated that the HSS8 sequence containing the three B-Myb sites may act as an enhancer when it is linked to thebcl-2 gene promoter. Interaction of B-Myb with HSS8 may enhancebcl-2 gene expression by co-operating with positive regulatory elements (e.g. previously identified B-Myb response elements) or silencing negative response elements in thebcl-2 gene promoter. [ABSTRACT FROM AUTHOR]

Autoimmune symptoms of (NZB×NZW)F1 (H-2d/z) mice are reported to be critically related to the heterozygosity at the H-2 complex of the murine major histocompatibility complex (MHC). We previously showed that several Aβz/Aαd MHC class II molecule-restricted autoreactive T-cell clones from B/WF1 mice were pathogenic upon transfer to preautoimmune B/WF1 mice. In this study, to identify the crucial amino acid residues in Aβz/Aαd molecules for T-cell activation, we generated a panel of transfectant cell lines. These transfectant cell lines express the Aβz/Aαd MHC molecules with a mutation at each residue α11, α28, α57, α69, α70, α76 of Aαd chain and β86 of Aβz chain. Replacing α69 alanine with threonine, valine or serine completely eliminated the ability to stimulate autoreactive T-cell clones without affecting the ability to present foreign antigen keyhole limpet haemocyanin (KLH) or l-plastin peptide to specific T-cell clones. Replacing β86 valine with aspartic acid resulted in a decrease in the stimulation for antigen-reactive as well as autoreactive T-cell clones. Substitutions at other residues had minimal or no effect on the stimulation of either auto- or antigen-reactive T-cell clones. These results suggest that alanine at residue 69 of the Aαd chain is critical for the activation of autoreactive Aβz/Aαd-restricted T-cell clones. Possible explanations for this are discussed. [ABSTRACT FROM AUTHOR]

IgA antibodies in the mucosal immune system are produced specifically to environmental antigens such as virus and bacteria, and possibly to some food components, which will provide a potential luminal antigen, DNA. To study the immune response to DNA in the gut, we established B-cell hybridomas producing IgA monoclonal antibodies (mAb) from Peyer’s patches (PP) of non-immunized, non-autoimmune, specific pathogen-free BALB/c mice, and examined their specificity by enzyme-linked immunosorbent assay (ELISA). Three mAb out of 18 bound strongly to self, bacterial and synthetic DNA, with Kd of about 10-7 m. One of the three mAb also reacted with the histone component and another reacted with some mouse food component. The VH genes of these three mAb have not previously been reported to have anti-DNA specificity, and carry putative somatically mutated sites favouring DNA binding in CDR. The features resemble those of anti-DNA antibodies found in human and murine models of systemic lupus erythmatosus (SLE), and are indicative of an antigen-driven selection process. Our findings suggest that even in normal healthy animals, anti-DNA antibodies of IgA isotype can be produced in certain peripheral environments such as in PP by spontaneous antigenic stimulation. [ABSTRACT FROM AUTHOR]

Although prostaglandin (PG) E2 is known to suppress various macrophage functions, the molecular mechanisms by which that occurs are lately unknown. To understand better those mechanisms, differential screening of a cDNA library from PGE2-treated macrophages was performed. Subsequently, the DNA sequence of a differentially expressed cDNA clone was determined and the cDNA was identified as B-cell translocation gene-1 (BTG1), a recently cloned antiproliferative gene. A two- to threefold increase in macrophage BTG1 expression was observed after PGE2 treatment. PGE1 and platelet-activating factor, but not leukotrienes B4, and C4, or lipopolysaccharide, also enhanced BTG1 expression. Furthermore, this effect was mimicked by dibutyryl cAMP which indicated the involvement of elevated cAMP in the PGE2-mediated enhancement of BTG1. Moreover, there was an inverse correlation between BTG1 mRNA expression and macrophage proliferation; however, BTG1 alteration was not associated with macrophage tumoricidal activation. Thus, BTG1 may play a role in PGE2-mediated inhibition of macrophage proliferation and not activation. [ABSTRACT FROM AUTHOR]

Recently, a cDNA encoding a newly identified rat antigen (HIS50 Ag) that binds to monoclonal antibody (mAb) HIS50 was cloned and shown to be homologous to cDNA encoding murine heat-stable antigen (HSA) and human CD24. Here we show that, like CD24 and HSA, at least part of HIS50 Ag is inserted into the plasma membrane by a glycosyiphosphatidylinositol (GPI)-lipid linkage and we describe its expression in rat haemolymphopoietic tissues. HIS50 Ag expression was almost exclusively confined to B lymphoid cells, the vast majority of T lymphoid cells, erythroid and myeloid cells were HIS50 -. Cell suspension analysis indicated that in bone marrow (SM) almost all Thy-1 + cells, H1S24 + cells [H1S24 recognizes the B-cell form of leucocyte common antigen (LCA)], terminal deoxynucleotidyl transferase-positive (TdT +) cells and (c + s)κ + cells expressed HIS50 Ag, and all (c+s)μ+ cells. A presumably early population of B lymphoid cells, expressing HIS24 Ag without HIS50 Ag, TdT or immunoglobulin (HIS24+HIS50- TdT- Ig-), constituted 1 .6% of BM nucleated cells. In blood, one-fifth of mononuclear cells were HIS50+, and about 85% of these expressed μ and/or κ chains. In spleen, flow cytometry analysis and immunohistology demonstrated heterogeneous expression of HIS5O Ag: immunoglobulin M (IgM)bright cells (as found largely in red pulp and marginal zone) were HIS50bright, while IgMdull cells expressed low or undetectable levels of HIS 50 Ag. Germinal centre B cells expressed high levels of HIS50 Ag. Germinal centres of lymph nodes and tonsil of man also bound HIS50. We conclude that HIS50 Ag expression in the haemolymphopoietic system of rat is virtually restricted to the B lineage. [ABSTRACT FROM AUTHOR]

The spontaneous regression of AK-5 histiocytoma is mediated by natural killer (NK) cells through antibody-dependent cell-mediated cellular cytotoxicity (ADCC) and the target cell death involves necrosis and apoptosis. We have studied the NK cell activation and the associated induction of apoptosis in the AK-5 tumour in rats. NK cells from immune animals expressed very low levels of CDI6 and CD25 surface receptors, as revealed by Northern hybridization and flow cytometry. Interaction between NK cells and antibody-tagged AK-5 cells triggered the expression of these receptors to a higher level and affected AK-5 killing. Treatment of naive NK cells in vitro with interleukin-2 (IL-2), interferon-γ (IFN-γ) and IL-12 also enhanced the expression of these activation markers. Co-culture of NK cells from immune animals with antibody-tagged AK-5 cells induced formation of nuclear bodies in AK-5 and extensive fragmentation of AK-5 cell DNA. NK-mediated apoptosis was inhibited by zinc, actinomycin D and cycloheximide. The in vitro treatment of NK cells with cytokines enhanced their ability to induce apoptosis in AK-5 turnout. These results suggest that the NK cells acquire their ability to induce apoptosis in AK-5 tumour in association with their optimal activation. [ABSTRACT FROM AUTHOR]

Affinity-purified human polyclonal anti-double-stranded DNA antibodies (anti-dsDNA) exerted a cytostatic effect towards human and rat glomerular mesangial cells (MC). In order to identify the cognate antigens for anti-dsDNA on the surface of MC, we used these autoantibodies to probe a human renal λg11 cDNA expression library. Two cDNA clones encoding the cognate proteins for the autoantibodies were isolated. Sequencing analysis of the two cDNA showed that they had 98.6% homology with the gene of the P0 and 99.2% homology with the gene of the Pi human acidic ribosomal phosphoproteins (P protein). Two galactosidase fusion proteins (125 000 and 150 000 MW) derived from the two cDNA inserts expressed in lysogenic Escherichia coli Y1089 could react with the original screening antibodies in an immunoblotting analysis. After transformation and expression of the full-length P1 clone in prokaryotic cells, the purified P1 protein was able to react with anti-dsDNA. In a cross-inhibition experiment, the dsDNA binding activity of anti-dsDNA was inhibited by a synthetic polypeptide corresponding to the carboxyl terminal 20 amino acids of P protein and purified P1 protein in a dose-dependent manner, but this was less potent than the inhibition caused by calf thymus dsDNA. By use of well-defined systemic lupus erythematosus (SLE) sera, we found only sera containing a high titre of anti-dsDNA activity (>300 IU/ml) reacted with P1 of rat MC lysate. Furthermore, the 38000 and 19000 MW macromolecules were proved to be the cognate antigens for anti-dsDNA expression on the surface of the MC, by Western blot of the MC plasma membrane lysates. These results suggest that antidsDNA may cross-react with ribosomal P proteins expressed on the surface of the MC and exert cytostasis towards these cells. [ABSTRACT FROM AUTHOR]

We characterized autoreactive T-cell clones derived from (NZB x NZW)F1 (B/WFI) mice. These autoreactive T-cell clones are shown to be CD4+ by immunofluorescence staining and to belong to Th2 type by cytokine release assay. Specificity analysis revealed the existence of mixed haplotype Aβz/Aαd major histocompatibility complex (MHC) class II molecule-specific T-cell clones as well as Aβz/Aαz- or Aβd/Aαd-specific T-cell clones. Some but not all of the mixed haplotype Aβz/Aαd- specific autoreactive T-cell clones showed strong activity to induce IgG anti-DNA antibody production upon transfer to young (4-month-old) B/WFI mice, indicating that T cells with these specificities might be involved in B/WF1 autoimmunity. [ABSTRACT FROM AUTHOR]

We have cloned, sequenced and expressed a cDNA encoding the α-chain of feline CD8. This clone, named FT8-10, has an open reading frame with 720 nucleotides in length encoding a protein with 239 amino acid residues. Sequence analysis has revealed that the feline CD8 α-chain (CD8α) shares significant homology with human (T8/Leu-2), bovine (BoCD8), rat (MRC OX8) and mouse (Lyt-2) CD8α subunits. Cysteine residues as well as the tyrosine kinase p56kk binding site are well conserved. Besides, no putative N-linked glycosylation site was found. Interestingly, immunofluorescence analysis of COS-7 cells transfected with feline CD8α expression plasmid driven by SRα promoter showed that the expressed feline CD8α cross-reacted with an anti-human CD8α monoclonal antibody OKT8, but did not react with an anti-feline monoclonal antibody, FT-2, which is thought to recognize the feline analogue of the human T8/Leu-2 and murine Lyt-2 molecules expressed on cytotoxic/suppressor T cells. [ABSTRACT FROM AUTHOR]

The B oligomer of pertussis toxin serves as a weak mitogen in the I lymphocyte, an effect which is associated with an early rise in cytosolic free calcium concentrations, as monitored by Fura-2 fluorescence. Upon co-administration of phorbol dibutyrate, a phorbol ester tumour promotor which activates protein kinase C, pertussis toxin-induced proliferation was synergistically enhanced, as measured by the increased uptake of[³H]thymidine, into cellular DNA. Although phorbol esterco- administration has often been associated with an inhibition of Ca2+-mobilizing pathways, phorbol dibutyrate pretreatment had no inhibitory effect on the pertussis toxin-induced calcium flux and may actually have enhanced this response slightly. Flow cytometric analysis of cell populations expanded by the combined regimen did not provide evidence for the preferential expansion of cells bearing either CD4 or CD8, the T-cell determinants representative of the helper-inducer and cytotoxic- suppressor subsets, respectively. Pertussis toxin and phorbol dibutyrate appear, therefore, to elicit polyclonal stimulation, rather than the selective activation of a given lymphocyte subset. Expression of the transferrin receptor, a marker for nutrient uptake, and CD25, the Tac component of the interleukin-2 (IL-2) receptor, was, however, synergistically enhanced in cells activated by the co- treatment procedure. [ABSTRACT FROM AUTHOR]

Spleen cells from MRL-lpr/lpr, CBA and BALB/c mice were cultured in vitro and assayed for production of anti-nuclear antibodies. Spleen cells from all species produced IgM antibodies to a nRNP (Ul-RNP)-specific antigen and to double-stranded DNA (dsDNA) after stimulation with LPS. The specificity of the anti-nRNP antibodies was shown, by immunoblotting, to be directed against the 33,000 MW polypeptide of nRNP/Sm. CBA mice produced more IgM autoantibody in vitro than MRL/lpr or BALB/c mice. In contrast, IgG anti-nRNP and anti-dsDNA antibody were not produced by any of the strains. Our data show that anti-nRNP and anti-dsDNA precursor B cells are part of the normal murine immune repertoire and are not confined to the MRL/lpr strain. This suggests that the spontaneous development of anti-nRNP and anti-dsDNA antibodies associated with systemic lupus erythematosis (SLE) is dependent on clonal stimulation and removal of suppressive influences. [ABSTRACT FROM AUTHOR]

The activities of two forms (7.5 and 5.5 S) of DNA ligase and of terminal deoxynucleotidyl transferase (TdT) have been studied in human thymocytes at different ages from 20 weeks pre-natal to 37 years after birth. Thymocytes have been selected on the basis of relative size and antigenicity (CD3, OKT3 immunofluorescence) with the cell sorter. For DNA ligases, three kinds of cells can be distinguished: (i) large antigenically negative cells of 20-week fetus, expressing only the 7.5 S enzyme; (ii) large antigenically positive cells without ligase activity; (iii) smaller antigenically positive cells, expressing only the 5.5 S enzyme. This last form of enzyme is found after birth. With respect to TdT expressed in OKT3- 5 μm cells and to OKT3+ thymocytes, it is observed that 5.5 S DNA ligase is found in a thymocyte population distinct from cells expressing TdT. Therefore, these results allow us to consider the 5.5 S DNA ligase activity as an additional functional marker for thymocyte maturation in humans. [ABSTRACT FROM AUTHOR]

MRL/MP-1pr/1pr (MRL/1) mice spontaneously develop an age-related autoimmune disease concomitant with interleukin-2 (IL-2) defects. Induction of IL-2 receptor (IL-2R), IL-2 production and subsequent de novo DNA synthesis in M RL/ 1 mice by the tumour-promoting phorbol ester 12-o- tetradecanoyl phorbol 13-acetate (TPA) and calcium inonophore (A23 187) were examined. These two compounds given together induced significant IL-2R expression, IL-2 production, and de nova DNA synthesis of spleen cells from this murine strain, as did concanavalin A (Con A) plus TPA. TPA and A23 187 may bypass the early steps of activation by mitogens in murine lymphocytes. However, even though these IL-2 defects could be overcome to some extent, the response of MRL/I mice to these stimuli was considerably lower than the enhanced IL-2R expression and IL-2 production of MRL/MP- + / + (M R L/n) control mice. These results suggested that the failure to respond to mitogens in these mice may be due, at least in part, to failure of receptor signal transduction, and to defects of molecular and biochemical reactions following signal transduction. [ABSTRACT FROM AUTHOR]

A library of monoclonal antibodies (MCA) reactive with DNA was derived from mice with lupus-like disease. The combining reactions of the antibodies was determined by ELISA, precipitation assay and indirect immunofluorescence assay on cells. On the basis of their reactions in these assays, the MCA have been classified into five taxonomic groups. MCA in Group I react with conformational determinants on double-stranded DNA (dsDNA); those in Group H with conformational backbone-dependent sugar-phosphate determinants on dsDNA and single-stranded DNA (ssDNA); those in Group III with determinants predominantly expressed on dsDNA; those in Group LV with base-dependent determinants on dsDNA, and those in Group V with determinants on both DNA and RNA. It is concluded that antis bodies which react with DNA are collectively of limited heterogeneity with regard to their specificity. The study illustrates how, upon traditional interpretation, different assay systems may give discordant results in the assignment of specificity to antibodies reactive with DNA. [ABSTRACT FROM AUTHOR]

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 peptidogtycan (PG), LPS, protein A and PWM in homozygous xidor 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. [ABSTRACT FROM AUTHOR]

Studies were performed to further characterize the effects of saturated fatty acids on murine T lymphocyte proliferation. Flow cytometry was used to show that the inhibitory effects of stearic acid (18:0) on [³H]thymidine uptake can be correlated with changes in cellular DNA content. Additional studies using flow cytometry and fluorescein. diacetate as a viability stain showed that exogenous 18:0 was toxic for phytohemagglutinin (PHA)-stimulated T cells, whereas the viability of unstimulated T cells was less affected by 18:0. The inhibitory effects of 18:0 on T cell proliferation were evident as early as 4 hr after fatty acid addition and after a 10-hr exposure, the effects of 18:0 could not be reversed by washing the cells or by adding oleic acid (18:1). It is proposed that the inhibitory effects of 18:0 are dependent upon PHA-induced changes in T cell lipid metabolism. [ABSTRACT FROM AUTHOR]

Fifty-seven serum samples positive for antibodies to double-stranded DNA (dsDNA), singlestranded DNA (ssDNA) or small nuclear ribonucleoproteins (snRNP) selected from patients with systemic lupus erythematosus and mixed connective tissue disease, were examined for the IgG subclass distribution of these autoantibodies. It was shown that antibodies to dsDNA were relatively restricted to IgG1 and IgG3 subclasses whilst antibodies to ssDNA were equally distributed throughout the four subclasses. Antibodies to snRNP were essentially restricted to the IgG2 isotype. These isotype distribution patterns contrasted with that observed for total serum IgG. [ABSTRACT FROM AUTHOR]

Increased DNA synthesis and immunoglobulin secretion was observed in human peripheral blood lymphocytes (PBL) cultured in vitro with soluble protein A from Staphylococcus aureus (Sp-A). Optimal Ig secretion was obtained in 6 day cultures containing 1 × 106 cells/mI and 10 μg/ml Sp-A. The presence of 5 × 10-5 M 2-mercaptoethanol in the culture medium as well as careful selection of foetal calf serum were needed for optimal results. In response to Sp-A stimulation, the three main classes of immunoglobulins were secreted by PBL. In some individuals, concentration of Sp-A optimal for lgG and IgM secretion inhibited IgA production. Immunoglobulin-con-taming cells were less abundant (0.5-5% of total cells) and smaller in Sp-A than in PWM-stimulated cultures (5-15%). The data suggest that Sp-A and PWM stimulated different subsets of circulating lymphocytes. [ABSTRACT FROM AUTHOR]

α2HS glycoprotein was isolated from normal adult serum. The ability of α2HS glycoprotein to promote the endocytosis of radiolabelled DNA and radiolabelled latex particles by mouse macrophages was investigated. The results using both radiolabelled latex particles and radiolabelled DNA show that α2HS glycoprotein enhances the ability of mouse macro-phages to take up these radiolabelled substrates as compared to control cells. [ABSTRACT FROM AUTHOR]

The course of the increased number of liver macrophages and the origin of these cells were studied after intravenous stimulation by zymosan, stilboestrol, or corynebaeterium. The macrophages were isolated by digestion of the liver with pronase and DNAase. Zymosan doubled the number of liver macrophages per gram of liver and led to a four-to five-fold increase in the number of blood monocytes, whereas stilboestrol induced a four-fold increase of liver macrophages and a two-fold increase of blood monocytes. Corynebaeterium administration gave a two-fold rise in the number of liver macrophages and a six-fold increase of blood monocytes. The in vitro labelling index of the liver macrophages showed a transient but marked increase after the administration of zymosan or stilboestrol, but returned to approximately normal values 4 days after the stimulus. Hydrocortisone given 48 h before zymosan prevented this increase in the in vitro labelling index of liver macrophages, thus demonstrating that the mononuclear phagocytes labelled in vitro had recently been recruited from the bone marrow to the liver. Stimulation by stilboestrol or zymosan of mice labelled with [³H]-thymidine caused an increase in the number of labelled liver macrophages and blood monocytes as compared with the numerical course of the labelled Kupffer cells and monocytes in untreated mice. It may be concluded that this increase is attributable to the increased influx into the circulation of labelled monocytes from the bone marrow, which in turn migrate to the liver in larger numbers than are seen in the normal steady state. Local proliferation could not have been responsible for the increased number of labelled liver macrophages, because free (³H)-thymidine was no longer available when the stimulus was applied. Evidence supporting the bone marrow origin of the increased number of monocytes and liver macrophages after intravenous stimulation was provided by the course of the number of monocytes and liver macrophages in hydrocortisone-treated mice given zymosan as stimulus. [ABSTRACT FROM AUTHOR]

Cyclophosphamide was used to assess the role of suppressor cells in the contact sensitivity reaction. A single painting with 300 μg and 30 μg oxazolone produced poor contact sensitivity reactions (ear swelling). Cyclophosphamide (200 mg/kg) 2 days before painting increased the response to the lower doses but had less effect on the response to 3 mg oxazolone. A single feed with 10 mg oxazolone caused strong contact sensitivity while lower doses (10-1000 μg) caused poor responses. Cyclophosphamide increased the response to the lower doses but not to the highest dose of oxazolone. These results suggested that the poor response to painting and feeding lower doses of oxazolone was due to a suppressor system which was sensitive to cyclophosphamide. A different result was obtained when contact sensitivity was measured by arrival of radioactively labelled cells. Cyclophosphamide had the greatest effect on cell arrival when high doses were fed. This indicates that ear swelling and cell arrival measure separate aspects of the contact sensitivity response. The lower doses of oxazolone, which caused little contact sensitivity, reduced the response to a standard immunizing dose. This low dose unresponsiveness occurred after either painting or feeding (Chase-Sulzberger phenomenon). It did not occur in mice treated with cyclophosphamide before the first exposure to oxazolone. This suggested that the low dose unresponsiveness was due to suppressor cells. The response to oxazolone was also assessed by DNA synthesis in the regional lymph nodes. A small dose of oxazolone (30 μg) caused a peak of DNA synthesis on day four while a high dose (3 mg) caused a peak on day three. Pretreatment with cyclophosphamide depressed the response to 30 μg although it increased contact sensitivity. The secondary response was smaller than the primary on days 3, 4 and 5 after immunization but larger on day two. The depression but not the increase was prevented by cyclophosphamide and was probably due to a suppressor system. [ABSTRACT FROM AUTHOR]

Serum thymic hormone activity (TA) was determined in hereditary hypopituitary dwarf mice (dw/dw) and their littermates (+/dw or +/+). It was found to be very low in the dwarf animals in comparison to their littermates. At 14 weeks of age, the dwarf littermates exhibited significant glomerular lesions characterized by deposits of IgG, IgG1, IgG2, IgA, IgM and C3, which were augmented by thymectomy of adult females. In contrast, hypopituitary dwarf mice had minimal glomerular deposits of immunoglobulins. Unlike these animals, their littermates showed antinuclear antibodies (ANA) and anti-deoxyribonucleic acid (DNA) antibodies in their serum. The present findings are discussed in relation to recent hypotheses on: (1) the role of the hypophysis in thymus-dependent immunological functions; and (2) the significance of T-cell deficiency in the development of autoimmunity. [ABSTRACT FROM AUTHOR]

Rabbits immunized with complexes of denatured calf thymus DNA and methylated bovine serum albumin (MBSA) produced only IgM antibodies to denatured DNA, confirming the results of previous studies. In contrast, both IgM and IgG antibodies were induced by MBSA complexes of Trypanosoma brucei DNA. A similar response was observed by Gruenewald and Stollar (1973) to T2 bacteriophage DNA, in which the normal base cytosine is replaced by hydroxymethylcytosine. T2 bacteriophage DNA is known to have a high adenine+thymine (A+T) content. It is suggested that the 7S antibody response to MBSA complexes of T. brucei DNA might be linked to the high A+T content in the DNA (especially kinetoplast DNA) of the subgenus Trypanozoon. [ABSTRACT FROM AUTHOR]

A migration inhibition test on spleen explants from NZB mice of different ages (4, 8 and 12 months) was performed using 40 μg/mI of DNA. The results have shown increased positivity with ageing of experimental animals. [ABSTRACT FROM AUTHOR]

Immunological unresponsiveness to DNP--guinea-pig skin protein conjugate (DNP--GPSP) was induced by intravenous injections of dinitrobenzenesulphonic acid (DNBSO3) given before, simultaneously, or after sensitization with DNP-GPSP. The increased DNA synthesis in vitro by lymph node or peritoneal exudate lymphocytes from unresponsive guinea-pigs was suppressed only in animals tolerized by pretreatment with DNBSO3. The majority of guinea-pigs with the other two types of unresponsiveness showed an increased [³H]thymidine incorporation into lymph node--but not into peritoneal exudate lymphocytes. From these results two conclusions may be drawn: (1) the mechanism of unresponsiveness induced during the primary response is similar to that of desensitization and different from that of `classical' tolerance; (2) tolerogen given before the sensitization prevents both the increased DNA synthesis by lymph node and peritoneal exudate lymphocytes and the skin reaction. Tolerogen given during the primary response or after the sensitization prevents increased DNA synthesis by peripheral lymphoid cells (peritoneal exudate lymphocytes) and the skin reaction, whereas lymph node lymphocytes showed increased DNA synthesis. [ABSTRACT FROM AUTHOR]

Optimum conditions were determined for the stimulation of DNA synthesis in C58 spleen cells by phytohaemagglutinin and allogeneic BALB spleen cells. Maximum stimulation occurred in 3 days in both cases. The rate of DNA synthesis was constant over a 4-hour labelling period with tritiated thymidine. DNA synthesis was significantly enhanced by 15 mM bicarbonate. The peak response of C58 spleen cells to PHA and allogeneic BALB spleen cells occurred when the mice were 3-7 months old; it decreased thereafter. This finding is discussed in relation to age-dependent immune polioencephalomyelitis in C58 mice. [ABSTRACT FROM AUTHOR]

Cryoglobulin production in rabbits immunized with streptococcal vaccines began about 3 weeks after immunization began and maximum yields from fresh immune sera ranged from <01 mg/mi to >6 mg/mI in individual rabbits. The cryoglobulins contained IgM and IgG, antiglobulin that was mainly IgM, IgG homogeneous antibodies to streptococci, and DNA. It is postulated that cryoglobulins are formed in two stages: alteration of IgG followed by antigen- antibody precipitation with antiglobulin. [ABSTRACT FROM AUTHOR]

The ability of C57BL, C3H, and A strain marrow cells to proliferate on transplantation into irradiated isogenic, F1 hybrid, and backcross progeny mice has been investigated by the spleen-colony technique and by measuring the newly-formed DNA in the recipient spleen with [131I] 5-iododeoxyuridine. Transplants of C57BL cells grew poorly in (A × C57BL) F1 and in (C57BL × C3H) F1 and reciprocal hybrids, as compared with isogenic and allogeneic hosts, whereas C3H and A strain marrow grafts were successful in isogenic, F1 hybrid and backcross recipients. In segregating backcross progeny, i.e. in offspring from F1 hybrid females mated to C57BL males, the frequency of success or failure of the C57BL grafts suggested that the trait was controlled by a single pair of genetic determinants at an autosomal locus. The latter is apparently linked with, or part of, the H-2 region in the IXth linkage group. The experimental evidence suggested also that the failure of C57BL haemopoietic cell grafts in H-2 heterozygotes was not related to exhaustion of donor cells by excess of recipient isoantigen but rather to lack of expression in the heterozygotes of histocompatibility-related growth requirements yet undefined. These requirements are specific for haemopoietic cells, but not for skin grafts, and resulted most probably from the effect of genetic (inter-allelic) interaction involving H-2 or an H-2-linked locus. [ABSTRACT FROM AUTHOR]