MT Antigens Research Articles

The diagnosis of latent tuberculosis infection (LTBI): currently available tests, future developments, and perspectives to eliminate tuberculosis (TB).

Introduction:Despite great efforts, tuberculosis (TB) is still a major public health threat worldwide. For decades, TB control programs have focused almost exclusively on infectious TB active cases. However, it is evident that this strategy alone cannot achieve TB elimination. To achieve this objective a comprehensive strategy directed toward integrated latent tuberculosis infection (LTBI) management is needed. Recently it has been recognized that LTBI is not a stable condition but rather a spectrum of infections (e.g., intermittent, transient or progressive) which may lead to incipient, then subclinical, and finally active TB disease.Aim:Provide an overview of current available LTBI diagnostic test including updates, future developments and perspectives.Results:There is currently no test for the direct identification of live MT infection in humans. The diagnosis of LTBI is indirect and relies on the detection of an immune response against MT antigens, assuming that the immune response has developed after a contact with the biological agent. Tuberculin skin test (TST) and interferon gamma release assays (IGRAs) are the main diagnostic tools for LTBI, however, both present strengths and limitations. The most ancient diagnostic test (TST) can be associated with several technical errors, has limited positive predictive value, is being influenced by BCG vaccination and several conditions can reduce the skin reactivity. Notwithstanding these limitations, prompt identification of TST conversion, should orientate indications for preventive therapy of LTBI. IGRAs have superior specificity, are not affected by M. bovis, BCG vaccination and other environmental mycobacteria. However, they present some logistical and organisational constraints and are more expensive. Currently, the WHO guidelines recommend that either a TST or an IGRA can be used to detect LTBI in high-income and upper middle-income countries with estimated TB incidences less than 100 per 100,000 population. Two skin tests (C-TB and Diaskintest), using only two specific M. tuberculosis antigens (ESAT-6 and CFP-10) instead of the tuberculin solution, have recently been developed but, to date, none of these tests is available on the European market.Conclusion:Early identification and treatment of individuals with LTBI is an important priority for TB control in specific groups at risk within the population: this is of crucial meaning in recently infected cases both at the community level and in some occupational settings. Currently there is no gold standard test for LTBI: an improved understanding of the available tests is needed to develop better tools for diagnosing LTBI and predicting progression to clinical active disease.

A new HLA-DP (SB) specificity (Cp63) defined in Japanese and Caucasian cell populations by cloned PLT cells

Cp61, Cp62, and Cp63 are HLA-DP (SB) specificities detected by PLT testing using cloned PLT cells derived from Japanese cell donors. It was confirmed, using Japanese and Caucasian cell panels, that Cp61 is identical to DPw5 and Cp62 is identical to DPw4. Cp63, however, was found not to correlate with any known HLA-DP specificities. The gene frequency of Cp63 was found to be 3.6% in Japanese ( N = 42) and 1.9% in Caucasian ( N = 52) cell panels of limited size. No triplet assignment of DPw specificity including Cp63 and found in the Japanese and Caucasian cell populations. The relationship between the Cp63 and HLA antigens demonstrated no significant correlation with HLA-A,B,C,DR, or MT antigens in this study. Linkage between Cp63 and HLA was confirmed from family segregation studies. This is the first report of a new DP specificity termed Cp63.

HLA-A, B, C, DR, MT, and MB antigens in recurrent aphthous stomatitis

In this report we have investigated the frequencies of HLA-A, B, C, DR, MT, and MB markers in 26 Silician subjects affected by recurrent aphthous stomatitis (RAS) and in 84 healthy controls. Our data show that the frequency of HLA-DR7 antigen is significantly increased in RAS-affected persons (61.5% versus 21.4%; pc < 0.0025), whereas the B5 antigen frequency is decreased significantly (absent in patients versus 27.3% in controls; pc = 0.04). Thus, present results suggest that HLA-linked genetic factors may play a role in the development of RAS.

Expression of HLA-DR, MB, MT and SB antigens on human mononuclear cells: identification of two phenotypically distinct monocyte populations.

The expression of HLA-DR, SB, MB, and MT antigens in different populations of human mononuclear cells was investigated with the use of monoclonal antibodies that recognize distinct human Ia-like antigens. Our results indicate that in man, as previously reported in other species, two phenotypically distinct populations of monocytes or macrophages can be identified on the basis of expression of Class II MHC antigens. Virtually all circulating monocytes displayed determinants associated with HLA-DR, SB, and MT. In addition, a subpopulation of human monocytes expressed MB/DS-associated antigens, as detected with monoclonal antibodies specific for MB1, MB3, and DS-framework determinants. Most B lymphocytes expressed antigens associated with HLA-DR, and the specificities SB2, SB3, MB1, MB3, MT2, and MT3 were also present. Resting T lymphocytes were unreactive with antibodies that recognize all of the Class II MHC antigens tested. T lymphocytes activated by soluble antigen or alloantigens, and expanded in culture, expressed DR, SB, MB, and MT. The majority of the MB/DS+ cells present in the adherent population were monocytes, because they were phagocytic and had the monocyte-specific marker 63D3. The rest of the cells were not identified. They are likely to include mostly B lymphocytes. The presence of other cells, such as dendritic cells, in this subset needs to be determined.

HLA-A, B, C; -DR; -MT, -MB, and SB antigens on unstimulated human endothelial cells.

Since major histocompatibility complex (MHC) antigens of class II play an important role in organ transplantation, we attempted to demonstrate their expression on endothelial cells which are abundant in transplants with vascular blood supply. Our analysis was performed with monomorphic and polymorphic monoclonal antibodies employing a microscopic immunofluorescence assay and flow cytometry on unstimulated endothelial cells isolated from umbilical cord veins. No evidence was found for the presence of HLA-DR antigens and determinants associated with MT, MB and SB. MHC class I antigens exhibited reduced expression. These findings were confirmed in respect to alloantigens by the use of conventional cytotoxic tissue typing antisera. MB and SB antigens were present on most cord B lymphocytes, but could only be demonstrated on a subpopulation of monocytes exhibiting a lower antigen density at the cell surface. MT and DR antigens were found on most cord monocytes and B lymphocytes.

N-terminal amino acid sequences of the polyoma middle-size T antigen are important for protein kinase activity and cell transformation.

We constructed deletion mutations which removed N-terminal coding sequences of various lengths from a cloned polyoma middle-size T antigen (MT antigen) gene. We introduced the MT antigen genes into a simian virus 40 expression vector so that they were expressed at high levels under the control of the simian virus 40 late promoter in COS-1 cells. The deletion mutant genes synthesized truncated MT antigens whose size was consistent with the deletion of either 70 or 106 amino acids from N termini, owing to initiation of translation at internal methionine codons in the MT antigen-coding region. The truncated MT antigens were found in cell membrane fractions but failed to show MT antigen-associated protein kinase activity. The cloned deletion mutant DNAs failed to transform rat F2408 or mouse NIH 3T3 cells. Therefore, N-terminal amino acid sequences of the polyoma MT antigen, as well as C-terminal sequences, are important for protein kinase activity and cell transformation.

N-terminal amino acid sequences of the polyoma middle-size T antigen are important for protein kinase activity and cell transformation.

We constructed deletion mutations which removed N-terminal coding sequences of various lengths from a cloned polyoma middle-size T antigen (MT antigen) gene. We introduced the MT antigen genes into a simian virus 40 expression vector so that they were expressed at high levels under the control of the simian virus 40 late promoter in COS-1 cells. The deletion mutant genes synthesized truncated MT antigens whose size was consistent with the deletion of either 70 or 106 amino acids from N termini, owing to initiation of translation at internal methionine codons in the MT antigen-coding region. The truncated MT antigens were found in cell membrane fractions but failed to show MT antigen-associated protein kinase activity. The cloned deletion mutant DNAs failed to transform rat F2408 or mouse NIH 3T3 cells. Therefore, N-terminal amino acid sequences of the polyoma MT antigen, as well as C-terminal sequences, are important for protein kinase activity and cell transformation.

Characterization of viable mutants of polyomavirus cold sensitive for maintenance of cell transformation

We mutagenized a cloned fragment of polyoma DNA encoding portions of the middle size (MT) and large T antigens. We regenerated infectious viral genomes containing the mutagenized DNA and tested their transforming ability at 32 and 39 degrees C. We isolated three nontransforming mutants and two mutants which were cold sensitive for the maintenance of cell transformation. The nontransforming mutants contained amber termination codons in the reading frame for the MT antigen. They synthesized truncated MT antigens which lacked MT-associated protein kinase activity. The cold-sensitive mutants synthesized MT antigens indistinguishable from wild type with regard to size, stability at 32 and 39 degrees C, intracellular location, and associated protein kinase activity. One of the mutants was shown by nucleotide sequence analysis to contain a single amino acid change in the MT antigen, located two residues upstream from the C-terminal hydrophobic region, and no changes in the large T antigen. The other mutant contained two amino acid changes in the MT antigen and two amino acid changes in the large T antigen.

Molecular identifications of HLA-DR4, MT3, and TB21 antigens on HLA-DR4 homozygous B cell lines.

The HLA-DR locus in the human major histocompatibility complex determines a series of polymorphic cell surface antigens; these antigens are composed of two noncovalently associated glycoproteins of 34,000 daltons and 29,000 daltons and are predominantly expressed on B cells, monocytes, and activated T cells (1). To date, 10 HLA-DR specificities have been well characterized by using alloantisera obtained from multiparous women (2). In addition to these DR antigens, two other B cell alloantigen systems (MT and MB) were proposed on the basis of the serologic data (3,4); the MB1 or MT1 specificities are found in association with DR1, DR2, and DRw6, whereas MT2 is associated with DR3, DR5, DRw6, and DRw8; MT3 is associated with DR4, DR7, and DRw9, and MB3 or MT4 is associated with DR4, DR5, and DRw8, respectively (3, 4). We have also described that the TB21 antigen is expressed in association with DR4, DR5, and DRw9 (5). The HLA-DR, MB, MT, or TB antigens are collectively referred to as class II antigens. The number of human class II antigens has been of primary concern because of their similarity to murine Ia antigens and especially because of their close relationship to certain diseases. With the aid of immunochemical means and alloantisera, it has been demonstrated that at least two loci control human class II molecules (6-10). The data presented in this report show the existence of three class II molecules carrying well-known allospecificities, DR4, MT3, and TB21, on HLA-DR4 homozygous cell lines.

Polyoma middle-sized T antigen can be phosphorylated on tyrosine at multiple sites in vitro.

The polyoma middle-sized T antigen (MT antigen) is associated with a protein kinase activity which phosphorylates tyrosine residues in polyoma T antigens in vitro. We have studied the sites of tyrosine phosphorylation of MT antigens phosphorylated in immunoprecipitates or in soluble form after partial purification by immunoaffinity chromatography. By analyzing the amino acid sequences of tryptic peptides of MT antigen, and by analyzing deletion mutant MT antigens, we have identified two major sites of phosphorylation in MT antigen, tyrosines 250 and 315. Additional sites were phosphorylated under some conditions. A synthetic peptide (Glu.Glu.Glu.Glu.Tyr.Met.Pro.Met.Glu), corresponding to the sequence around tyrosine 315, was phosphorylated when added to immunoprecipitates containing MT antigen.

Strong association of idiopathic membranous nephropathy with HLA-DR2 and MT1 in Japanese.

HLA-A, B, DR, and MT antigens were examined in 50 patients with idiopathic membranous nephropathy (IMN) by the standard microlymphocytotoxicity technique. The frequency of HLA-DR2 was significantly increased in the patients in comparison to the controls. Significant decreases in the frequencies were seen for HLA-DR4, DRw8 and DRw9 in the patients. The linkage disequilibrium between HLA-Bw52 and DR2 was noted in the controls, but it was significantly weaker in the patients. The frequency of MT1 was significantly higher, and that of MT3 was significantly lower in the patients as compared with the controls. The findings suggest that an immunological disturbance under the influence of genetic factors may confer a susceptibility to IMN.

Expression of T-lymphoblast-encoded HLA-DR, MT, and SB antigens on human T-B lymphoblast hybrids

The Ia-like antigens of hybrids of the B-lymphoblastoid cell line (B-LCL) W1-L2 and a subline of the T-lymphoblastoid cell line (T-LCL) HSB were examined. Antigens of the HLA-DR and MT series were analyzed by indirect immunofluorescence with chimpanzee anti-DR sera and monoclonal antibodies, and antigens of the SB series were analyzed by primed lymphocyte typing (PT). The W1-L2 × HSB hybrids expressed antigens of each series not found on either parent cell. In each case, the novel antigens were indistinguishable from those found on SB, a B-LCL established from the same individual as HSB, and are thus presumably HSB encoded.

HLA-DR MT and MB antigens in Takayasu disease.

Recent studies on the pathogenesis of Takayasu disease have focussed on the participation of genetic factors, and HLA analysis has confirmed the close relationship between Takayasu disease and HLA Bw52. In an attempt to investigate the association of immune response gene with the disease, HLA-DR (DR-1, -2, -3, -4, -5, -w6, -7, -w8, -w9, -w10), MT (-1, -2, -3), MB (-1, -3) antigens were studied in 52 patients with Takayasu disease and the data compared with findings in healthy Japanese. As there were no statistical differences between the two groups in the frequencies of all these antigens, genetic factors in Takayasu disease may be much more closely associated with B than with D loci.

A new B‐cell alloantigen, TB21, coded for in the HLA‐D/DR region

A new B-cell alloantigen, designated as TB21, was serologically defined by 2 monospecific sera, T383 and T2200. Both T383 and T2200 had cytotoxic titers of 1:8 against TB21 positive B cells and were highly correlated to each other (r = 0.876). The phenotype frequency of TB21 was approximately 55% in the Japanese population. TB21 was strongly associated with DRw9 and weakly with DR5, but was definitely distinct from the known supertypic specificities such as MT or MB antigens. Family studies showed that TB21 segregated with different DR antigens on different haplotypes, indicating that TB21 is coded for by a gene at a closely linked but distinct locus from HLA-DR. Furthermore, TB21 was preferentially detected on B cells but not on monocytes by complement-dependent cytotoxicity. Failure of detection of TB21 on monocytes further distinguished the TB21 antigen from DR and MT antigens. Results of this study suggest that there exist 2 kinds of B-cell alloantigens coded in the HLA region: DR and MT antigens, and other B-cell alloantigens represented by TB21.

Serologic identification of the human secondary B cell antigens. Correlations between function, genetics, and structure.

The secondary B cell (SB) antigens are polymorphic HLA-linked antigens on human B cells and macrophages that are identified by primed T cell responses but are genetically distinct from the HLA-DR, MB, and MT antigens. Serologic identification of the SB molecule, using the monoclonal antibody ILR1, now makes it possible to correlate the function of these determinants in human T cell recognition with an Ia-like molecular structure and a genetic locus that marks a new HLA subregion. Three lines of evidence indicate that the ILR1 molecule identifies an epitope on some alleles of the SB gene: (a) the polymorphism of ILR1 -reactivity in the population correlates with SB2 SB3; (b) T cell proliferative response to SB2 and SB3 are specifically inhibited by ILR1; and (c) ILR1 reactivity is exactly concordant with the expression of SB2 in a panel of HLA-deletion mutant lymphoblastoid cell line. Together with previous studies, these results indicate that the SB antigens are on Ia-like molecules. Furthermore, the serologic studies of HLA-deletion mutant cell lines demonstrate that there are two HLA regions centromeric to HLA-B controlling expression of Ia-like molecules: a region toward HLA-B that controls expression of HLA-DR, and a region toward GLO that controls expression of SB.

Association of PLT specificity of alloreactive lymphocyte clones with HLA-DR, MB and MT determinants.

The HLA-D region encodes for several serologically defined systems, including DR, MB, and MT. The antigens of MB and MT are strongly associated with two or more DR specificities. The purpose of this study was to determine the role of MB and MT antigens in lymphocyte alloactivation. A soft agar colony assay was used to generate alloreactive lymphocyte clones primed in mixed leukocyte culture against a stimulator who typed as HLA-DR4,-;MB3,-;MT3,-. In secondary primed lymphocyte typing (PLT) assays, several clones were identified with PLT specificities strongly associated with DR4, MB3, or MT3. The data suggest that HLA-D controls different lymphocyte-activating determinants associated with the serologically defined DR, MB, or MT antigens.

HLA-DR molecules bear the MB and MT antigens: [formula omitted], Depts. of the Med. and Path. and the HHMI Lab at the Washington Univ. Sci. of Med., St. Louis, MO, Immunology Branch, NCI, Bethesda, MD, and the Histocompat. Testing Lab, Miss. Gen. Hosp., Boston, MA.

HLA-DR molecules bear the MB and MT antigens: [formula omitted], Depts. of the Med. and Path. and the HHMI Lab at the Washington Univ. Sci. of Med., St. Louis, MO, Immunology Branch, NCI, Bethesda, MD, and the Histocompat. Testing Lab, Miss. Gen. Hosp., Boston, MA.

Lymphocyte Transformation in Rickettsioses

Abstract Lymphocyte transformation was studied with leukocytes from persons who had received rickettsial vaccines or had been infected with rickettsiae. The antigens were prepared from normal yolk sacs or yolk sacs infected with Rickettsia prowazeki (ET), Rickettsia mooseri (MT), Rickettsia akari (RP), or Rickettsia rickettsii (SF). When the antigens were diluted 1:100 and the cultures incubated 5 days, the reactions to normal yolk sac were minimal and the reactions to rickettsial antigens were satisfactory. With persons infected with MT and with those vaccinated with ET vaccine, the reactions to ET and MT antigens were about the same. With persons infected with SF or vaccinated with SF vaccine, the reactions to RP and SF were also about the same. There was some cross-reaction between antigens of the typhus and spotted fever group. Five normal persons were followed during primary immunization with ET vaccine; two gained responsiveness to ET and MT antigens. Incubation in immune serum did not cause normal cells to gain responsiveness. For all donors, there was a rough correlation between complement-fixing antibody titer and lymphocyte transformation. Several persons with antibody titers less than 1:8 had elevated lymphocyte transformation.