Showing papers by "Walter and Eliza Hall Institute of Medical Research published in 1984"

Inducible expression of H-2 and Ia antigens on brain cells.

Abstract: Cells in the brain express unusually low levels of antigens encoded by the major histocompatibility complex (MHC)1,2. This is somewhat surprising as class I (H−2) and class II (Ia) MHC antigens have critical roles in immune responses3. The activation of T lymphocytes is associated with the enhanced expression of these antigens and this effect is mediated by a specific T-cell lymphokine, γ-interferon (IFN-γ)4–17. Here we show that IFN-γ induces a dramatic increase in the expression of H–2 antigens on the cells of the brain. After exposure to IFN-γ in vitro, all surviving cells, including most astrocytes, oligodendrocytes, microglia and at least some neurones, express H–2 antigens. Direct injection of IFN-γ into the brains of mice indicated that H–2 antigens were also induced in vivo. Furthermore, IFN-γ induced Ia antigens on a subpopulation of astrocytes. The induction of H–2 antigens by IFN-γ may render brain cells competent to initiate and participate in immune reactions and may therefore contribute to both immunoprotective and immunopathological responses in the brain.

Expression of myb, myc and fos proto-oncogenes during the differentiation of a murine myeloid leukaemia.

Abstract: It is widely thought that c-onc genes (or proto-oncogenes)—the cellular progenitors of retroviral transforming genes—are involved in cellular differentiation and/or proliferation. Such ideas originate primarily from the ability of v-onc genes and ‘activated’ c-onc genes to induce uncontrolled cellular proliferation, and their capacity to arrest or interfere with differentiation processes in some systems. Haematopoietic cell populations provide additional support for these ideas as c-myb RNA is present in cell lines corresponding to immature, but not mature, cell types1,2, and elevated levels have been found in tissues that are active in haematopoiesis2,3. We have now examined the effects of induced differentiation on c-onc gene expression in a murine myeloid leukaemia cell line, WEHI-3B (‘D+’ subline)4. Our results show that the expression of c-myb and c-myc, at the level of transcription, decreases only at late stages in the monocytic differentiation of WEHI-3B cells, while expression of c-fos increases markedly. We suggest that c-myb and c-myc do not themselves control myeloid differentiation, but that they function in the maintenance of the proliferative state of myeloid cells. The induction of c-fos may reflect its role in some macrophage-specific functions.

Molecular cloning of cDNA encoding a murine haematopoietic growth regulator, granulocyte-macrophage colony stimulating factor.

Abstract: cDNA clones specifying the murine granulocyte–macrophage colony stimulating factor have been isolated. This haematopoietic growth factor is encoded by a unique gene specifying a messenger RNA of 1,200 nucleotides and a polypeptide of 118 amino acids. It bears no structural similarity to the functionally related factor, interleukin-3, described recently.

T cell development in the adult murine thymus: changes in the expression of the surface antigens Ly2, L3T4 and B2A2 during development from early precursor cells to emigrants.

Abstract: Many (perhaps all) of the key events in T cell development take place within the thymus. Thymic lymphocytes are believed to be immature T cells at various stages of development. According to these tenets it should be possible to classify thymocytes into distinct subpopulations, and then order these groups into a sequence representing the intrathymic T cell development pathway. Certain T cell antigens are expressed differentially on the surface of thymocytes, and these have been used to define thymus subpopulations. Recent attempts to classify thymocytes in this way have produced a reassuring degree of agreement between different laboratories (reviewed by Smith 1984). However, there is no such consensus on the ordering of these subpopulations in a developmental pathway, the only point of agreement being that many of the earlier schemes must be wrong. In this review we survey our own work on the definition of thymocyte subpopulations using monoclonal antibodies directed against T cell surface antigens. We begin with a summary of earlier work on antigens used to distinguish cortical and medullary cells (reviewed in detail in Scollay & Shortman 1983), and then present more recent studies on antigens which help to further classify thymocytes

Effect of cloned interferon-gamma on expression of H-2 and Ia antigens on cell lines of hemopoietic, lymphoid, epithelial, fibroblastic and neuronal origin.

Abstract: Interferon-gamma (IFN-gamma), tested in the form of the product of a cloned murine IFN-gamma gene, was found to increase the expression of H-2 antigens on cultured cell lines of a wide variety of cell types including factor-dependent hemopoietic cells, pre-B and B cells, macrophages, T cells, mast cells and cell lines of epithelial, fibroblastic and neuronal origin. However, IFN-gamma induced Ia antigens on only B cells, macrophages and T-dependent mast cells or persisting cells. On the basis of these results, we suggest that a major function of IFN-gamma is to potentiate immune responses by enhancing the expression of H-2 and Ia antigens on a variety of cell types.

The ring-infected erythrocyte surface antigen (RESA) polypeptide of Plasmodium falciparum contains two separate blocks of tandem repeats encoding antigenic epitopes that are naturally immunogenic in man.

Abstract: We showed previously that the ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum contains a repetitive amino acid sequence. We have investigated here the sequence and antigenic relationships between RESA from FC27, a Papua New Guinea isolate, and from NF7, a Ghanaian isolate. The complete nucleotide sequences of eight different cDNA clones demonstrate that RESA from the two strains are closely homologous over the region that can be compared. A series of related eight, four and three amino acid repeats is located at the 3' end, forming the C terminus of RESA in FC27. RESA contains a second block of repeats based on an 11 amino acid sequence and separated from the 3' block by 381 amino acids in NF7. Antibodies from Papua New Guineans react with RESA from the African isolate, and vice-versa. Antigenic determinants that are naturally immunogenic in man are present in the 5' repeats of RESA, as well as in the 3' repeats, and antibodies that cross-react with both blocks of repeats were detected by reacting affinity-purified human antibodies with cloned subfragments of the cDNA clones, expressed in Escherichia coli.

Variant (6 ; 15) translocation in a murine plasmacytoma occurs near an immunoglobulin kappa gene but far from the myc oncogene.

Abstract: Chromosome translocations in B-lymphoid tumours are providing intriguing insights and puzzles regarding the role of immunoglobulin genes in the activation of the myc oncogene (reviewed in refs 1, 2). The 15 ; 12 translocations found in most murine plasmacytomas and the analogous 8 ; 14 translocation in human Burkitt's lymphomas involve scissions of murine chromosome 15 (human chromosome 8) near the 5' end of the c-myc gene and subsequent fusion near an immunoglobulin heavy-chain gene. The less well characterized 'variant' translocations found in about 15% of such tumours also involve the myc-bearing chromosome band, but exchange occurs with a chromosome bearing an immunoglobulin light-chain locus--in mice, the kappa-chain locus bearing chromosome 6 (refs 3-5) and, in man, chromosome 2 (or 22), at the same band at which the kappa (or lambda) locus lies (reviewed in ref. 1). The Burkitt variant translocations involve scissions 3' of c-myc; one 8 ; 22 translocation placed the C lambda locus just 3' of c-myc, but usually the chromosome 8 breakpoint is a greater, but unknown, distance away from c-myc, more than 20 kilobases (kb) in one 8 ; 2 translocation involving the C kappa gene. Little is known about the murine 6 ; 15 translocations, although a C kappa gene cloned from one plasmacytoma (PC7183) is linked, via chromosome 12 sequences, to an unidentified region of chromosome 15 (ref. 11). We describe here the chromosome fusion region from plasmacytoma ABPC4, which displays the typical reciprocal 6;15 translocations. We find that the chromosome 6 breakpoint is near C kappa but, unlike those in the heavy-chain locus, not at a position where immunoglobulin genes normally recombine. Moreover, the chromosome 15 sequences involved in the ABPC4 translocation are not derived from the vicinity of c-myc.

Serological diagnosis of Echinococcus granulosus infection in sheep using cyst fluid antigen processed by antibody affinity chromatography.

Abstract: Serum antibody responses in sheep naturally or experimentally infected with Echinococcus granulosus and/or other larval cestodes were examined using an enzyme-linked immunosorbent assay (ELISA) with various antigens prepared from sheep hydatid cyst fluid ( SHCF ). Serum donors included: sheep experimentally infected with E. granulosus and their age-matched non-infected controls; sheep experimentally infected with other helminth parasites; sheep naturally infected with E. granulosus both from Tasmania and the Australian mainland; sheep from Tasmania naturally infected with larval cestodes other than E. granulosus; and naturally reared sheep completely free from infection with larval cestodes. Attempts were made to eliminate serological reactions which were not specific for E. granulosus by using a series of antibody affinity chromatography steps to deplete crude SHCF antigen; these included adsorption with a monoclonal antibody, 3EgH 29-2, removal of host IgG using rabbit anti-sheep IgG antibody, and removal of antigens which bound non-specifically to normal sheep immunoglobulin. The final affinity-depleted antigen product was designated AD SHCF . Specific serological reactivity in infected sheep was very low. Affinity depletion of SHCF using 3EgH 29-2 did not appear to increase the specificity of serological diagnosis of E. granulosus infection when experimentally infected sheep were compared with their non-infected controls provided the latter were age-matched with experimental animals. The other affinity adsorption steps significantly reduced non-specific background binding to antigen by normal sheep serum. Despite this reduction in background in the ELISA, only low levels of antibody could be detected in naturally-infected sheep.(ABSTRACT TRUNCATED AT 250 WORDS)

Low dose cytosine arabinoside: partial remission of acute myeloid leukaemia without evidence of differentiation induction

Abstract: Summary. Thirteen patients with acute myeloid leukaemia aged from 19 to 81 were treated with low dose cytosine arabinoside (ARA-C) in a dose of 10–15 mg/m2 twice daily subcutaneously. Three complete remissions were obtained. Partial responses were observed in a further two patients. To analyse the action of low dose ARA-C freshly isolated leukaemic cells and cells from the cloned promyelocytic leukaemia cell line (HL60) were cultured in vitro in the presence of cytosine arabinoside. Minimal evidence of differentiation induction was observed when compared with the cytotoxic effects of the drug. These results suggest that ARA-C does not exert its anti-leukaemic effects by halting proliferation through differentiation induction. Rather, it appeared that the capacity of this agent to kill cells in S-phase produced a progressive depletion of the cycling leukaemic cells. This resulted in a corresponding steady decline in the total leukaemic cell population.

Tissue localization and retention of antigen in relation to the immune response.

Abstract: Antigen persists for months or even years in lymphoid tissues of immune animals and this antigen is believed to participate in the induction and maintenance of B-cell memory as well as in the maintenance of serum antibody levels. In the present report we describe the phenomenon of antigen localization and long-term retention on mouse follicular dendritic cells (FDCs). The antigens used were injected in the hind footpads of immune mice and the popliteal lymph nodes were the lymphoid organs generally studied. In addition to presenting the morphological features of mouse FDCs, we report the results of a study of the mechanism of antigen migration from the site of initial localization in the lymph node subcapsular sinus to the regions of follicular retention in the cortex. The migration was followed by light and electron microscopy. The results support the concepts that immune complexes are trapped in the subcapsular sinus and are transported by a group of nonphagocytic cells to follicular regions. The mechanism of transport may involve either migration of pre-FDCs with a concomitant maturation into FDCs, or cell-to-cell transport utilizing dendritic cell processes and membrane fluidity; or a combination of the two mechanisms may be in operation.

Detection of circulating antigen in bancroftian filariasis by using a monoclonal-antibody

Abstract: A monoclonal antibody designated Gib 13-5-2 (Gib 13) and directed against the cattle parasite Onchocerca gibsoni was used in a two-site immunoradiometric assay (IRMA) for detection of circulating antigen in the sera of Wuchereria bancrofti-infected individuals from Sri Lanka and Papua New Guinea. The microfilaremic patients were, in general, serum antigen positive by the Gib 13 IRMA. Among the amicrofilaremic patients, 47% of those with lymphedema, lymphangitis, hydrocele, etc., and 25% of those with elephantiasis had circulating antigen. Correlation of the presence of serum antigen with clinical status indicated that the Gib 13 target antigen in serum is probably an indicator of either active or early infection, or of both. The antigen was also detected in the urine of some patients. By sodium dodecyl sulphate polyacrylamide gel electrophoresis immunoblotting, Gib 13 target antigens of molecular weights 67,000 and 52,000 were identified.

T-cell development in the absence of a thymus: the number, the phenotype, and the functional capacity of T lymphocytes in nude mice.

Abstract: A small but definite proportion of T-lymphocyte-like cells have been reported in nu/nu (nude) mouse spleen despite the congenital absence of a thymus in these animals. We have determined the number and the characteristics of such cells using flow cytometry. The level of T-like cells increased with age. In 4-month-old nu/nu CBA spleen, 14% of all cells expressed some Thy 1 antigen. However, only 4% expressed mature T-cell levels, and only the 2% with the highest Thy 1 also showed a normal distribution of Ly 1 and Ly 2 antigens. These T-like cells were slightly larger than normal nondividing T lymphocytes. We have assessed the total functional capacity of T-like cells in nu/nu CBA spleen using a high-cloning-efficiency limit-dilution culture system. Almost all precursor cells capable of forming clones when stimulated with concanavalin A in the presence of irradiated spleen cells and growth factors, and almost all precursors of those clones that were cytolytic in a lectin-mediated tumor-cell-lysis assay, were within this 2% subpopulation of nu/nu spleen cells with mature T-cell markers. Increased levels of purified interleukin 2 failed to induce further precursor function, indicating that maturation of pre-T cells was not obtained. However the nu/nu spleen cells bearing mature T-cell markers displayed only 10-30% of the cloning efficiency of normal splenic T cells. The majority of nu/nu spleen T-like cells, even within this phenotypically "normal" subset, appeared to be nonfunctional. We conclude that the absence of a thymus leads to qualitative, as well as quantitative, deficiencies in the T-cell population, and various interpretations are discussed.

A strong association between the antinuclear antibody anti-La (SS-B) and the kappa chain allotype Km(1)

Abstract: The distribution of immunoglobulin allotypes of the Gm and Km systems was examined in 51 patients with antinuclear antibodies (ANA), which reacted with two saline-extractable non-DNA nuclear antigens, anti-La (SS-B) and anti-RNP, which characterize certain multisystem autoimmune diseases. Forty-six percent of the 26 patients with anti-La were positive for the Km(1) allotype compared with 14% of the 35 with anti-RNP and 16% of 1204 of healthy subjects (corrected P value 90%) in patients with anti-La are indicative of a substantial inherited predisposition to the development or expression of this autoantibody. The strong association between the Km(1) allotype and the anti-La response may be due to linkage disequilibrium between genes coding for the constant region of immunoglobulin kappa light chains and genes coding for the variable regions of kappa light chains which confer antibody specificity for the special configuration of the ribonucleoprotein known as La.

Comparison of thymic and peripheral T cell Ly-2/3 antigens.

Abstract: Major structural differences occur between the thymic and peripheral T cell forms of the Ly-2/3 antigen. Thymus Ly-2/3 consists of similar amounts of two types of disulfide-linked heterodimer, alpha beta and alpha' beta (Mr alpha = 38000, Mr alpha' = 35000, Mr beta = 30000). In contrast material from peripheral T cells consists almost exclusively of alpha beta dimers. The alpha chains of thymus and peripheral T cells differ also in isoelectric point with the thymic alpha chain being the more acidic. Based on peptide mapping experiments the alpha and alpha' chains of thymus are likely to be alternatively modified forms of the same polypeptide backbone. Individual T cell clones or T cell tumors propagated in vitro exhibit either a typical thymus or a typical peripheral T cell Ly-2/3 polypeptide pattern indicating that the synthesis of both alpha and alpha' chains can occur in the same cell. The heterogeneity of thymic Ly-2/3 can be considerably reduced by removal of sialic acid residues, and after desialylation the alpha chains of thymus and a cloned cytotoxic T lymphocyte (CTL) line cannot be electrophoretically distinguished. If Ly-2 structures affected the antigen specificity of CTL, a different structural variant would be expected in individual clones. The electrophoretic identity of desialylated thymus and CTL alpha chains suggests that Ly-2 does not exhibit clonal variation in polypeptide structure and, therefore, cannot contribute to antigen specificity.