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R L Modlin

Publications and source records attributed to R L Modlin.

At least 19 recordsLinked to original sources
PubMed1992

Cytokine patterns of immunologically mediated tissue damage.

Reactional states in leprosy are produced by different immunologic mechanisms and are responsible for a major component of tissue damage of the disease. Reversal reactions exhibit increased CD4 T cell infiltration in lesions and augmented cell-mediated immune reactivity to Ag of Mycobacterium leprae that can rapidly produce nerve damage. Erythema nodosum leprosum (ENL) reactions also have CD4 T cell infiltration but appear to be associated with the formation of immune complexes that are responsible for panniculitis, arthritis, vasculitis, and nerve injury. Because these reactional states may serve as paradigms for other types of human immunologically mediated tissue damage, this study sought to characterize the dynamic changes in cytokines associated with these reactions. Expression of cytokine mRNA in lesions of leprosy reactional states were measured by PCR. In reversal reactions, IL-1 beta, TNF-alpha, IL-2, and IFN-gamma mRNA were prominent and found to increase during the reaction, concomitant with decreases in expression of mRNA for IL-4, IL-5, and IL-10. In ENL, selective increases in the expression of IL-6, IL-8, and IL-10 mRNA was observed, with persistent expression of IL-4 and IL-5 mRNA. Reversal reactions represent naturally occurring delayed-type hypersensitivity reactions that favor macrophage activation and protective immunity, but which can engender concomitant cell injury. In contrast, ENL lesions represent immediate-type hypersensitivity reactions reflecting the selective stimulation of cytokines that attract neutrophils, stimulate antibody production, and down-regulate macrophage activation. The analysis of cytokine dynamics within different inflammatory responses can provide insights into immune mechanisms of tissue damage, and provide a useful framework for developing strategies for therapeutic intervention.

Base Sequence↗
PubMed1992

Cytokine production induced by Mycobacterium tuberculosis lipoarabinomannan. Relationship to chemical structure.

Lipoarabinomannan (LAM), a major cell wall component of Mycobacterium tuberculosis, exhibits a wide spectrum of immunoregulatory effects. To identify cytokines produced by human PBMC in response to LAM, we used PCR amplification to detect cytokine mRNA. LAM-induced transcription of mRNA for cytokines characteristically produced by macrophages, including TNF, granulocyte-macrophage-CSF, IL-1 alpha, IL-1 beta, IL-6, IL-8, and IL-10. In contrast, LAM did not induce transcription of mRNA for cytokines produced predominantly by lymphocytes, such as lymphotoxin, IFN-gamma, IL-2, IL-3, or IL-4. Measurement of concentrations of TNF, granulocyte-macrophage-CSF, IL-6, IL-10, IFN-gamma, IL-2, and IL-4 in cell culture supernatants indicated that cytokine release correlated with mRNA patterns. Lipomannan (LM) and phosphatidylinositol mannosides (PIM) are simpler versions of LAM. LM lacks arabinan, whereas PIM lacks both arabinan and most mannan residues. LAM, LM, and PIM induced transcription of cytokine mRNA, elicited cytokine production, and suppressed Ag-induced T cell proliferation, indicating that most of the biologic activity of LAM was associated with the phosphatidylinositol end of the molecule. In support of this conclusion, deacylation of LAM abrogated its capacity to induce cytokine production and suppress Ag-induced proliferation. The production of macrophage-derived cytokines induced by LAM may mediate clinical manifestations of tuberculosis such as fever, weight loss, and tissue necrosis, as well as immunoregulatory effects such as inhibition of Ag-induced proliferation and hyperglobulinemia.

Adult↗
PubMed1992

Immunoreactivity of a 10-kDa antigen of Mycobacterium tuberculosis.

Identification of Ag of Mycobacterium tuberculosis recognized by T cells is essential to understanding the pathogenesis of tuberculosis and mechanism(s) of resistance to infection. Previous studies evaluating the immunoreactivity of nitrocellulose transfers of M. tuberculosis Ag separated by SDS-PAGE indicated that a high proportion of M. tuberculosis-reactive T cell lines proliferate in response to a 10-kDa Ag. We therefore purified this Ag from M. tuberculosis culture filtrates and evaluated its immunoreactivity in patients with tuberculous infection. Proliferative responses of PBMC to the 10-kDa Ag were similar to those induced by whole M. tuberculosis and greater than those elicited by other proteins isolated from culture filtrate. Furthermore, in patients with tuberculous pleuritis, proliferative responses to the 10-kDa Ag were higher in pleural fluid mononuclear cells than in PBMC, indicating that T cell reactivity to this Ag is enhanced at the site of disease. The first 15 amino acids of the 10-kDa Ag were identical to those defined previously for Bacillus Calmette-Guérin-a (BCG-a), and a T cell clone recognized the 10-kDa Ag and a peptide of BCG-a, indicating that the 10-kDa Ag corresponds to BCG-a. This Ag elicited IFN-gamma production by pleural fluid mononuclear cells and by PBMC from healthy tuberculin reactors, suggesting that the 10-kDa Ag can enhance macrophage activation and resistance to mycobacterial infection. Our findings indicate that the 10-kDa Ag of M. tuberculosis is highly immunoreactive and should be evaluated for its capacity to elicit protective immunity.

Amino Acid Sequence↗
PubMed1992

Microanatomic clonality of gamma delta T cells in human leishmaniasis lesions.

T cells bearing gamma delta Ag receptors accumulate in the lesions of patients with localized American cutaneous leishmaniasis (LCL), and are thought to be involved in immunity to the parasite. To obtain clues as to the nature of the Ag recognized by these cells, we analyzed the diversity of the TCR delta-chain in LCL lesions. Using mAb against variable (V) encoded determinants with immunoperoxidase, both V delta 1 and V delta 2 subpopulations were identified in the dermal granulomas. However, within the epidermis of LCL lesions, the majority of the gamma delta T cells were V delta 1 positive. PCR analysis of lesion-derived DNA using oligonucleotide primers for V and junctional (J) gene segments revealed preferential usage of J delta 1 in lesions compared with the peripheral blood of these patients. Nucleotide sequence analysis of the V-J junction indicated limited diversity of gamma delta T cells within specific microanatomic regions. In addition, use of a single diversity (D) gene segment, D delta 3, in V delta 2 cells in lesions was observed, as opposed to multiple D delta gene segment usage in the blood of the same individuals. The distribution, gene segment usage and clonality of gamma delta T cells in lesions of leishmaniasis was remarkably similar to that observed in leprosy. Therefore, gamma delta T cells responding to infection may recognize a limited set of nominal Ag, perhaps common to distinct pathogens and/or those expressed by the host. Our findings are most consistent with a model in which specific gamma delta T cells are clonally selected by these Ag in lesions and undergo oligoclonal expansion within a microanatomic region.

Amino Acid Sequence↗
PubMed1992

Gamma delta T lymphocytes in human tuberculosis.

The manifestations of tuberculous infection reflect the immune response to infection. Most healthy tuberculin reactors develop protective immunity; tuberculous pleuritis reflects a resistant response manifest by mild disease, whereas advanced pulmonary and miliary tuberculosis reflect ineffective immunity. The role of gamma delta T cells was assessed in tuberculous infection by evaluating expansion of these cells from blood mononuclear cells after stimulation with Mycobacterium tuberculosis. After culture in vitro, the percentages of gamma delta+ cells were significantly greater in patients with protective and resistant immunity (tuberculin reactors, 25% +/- 4%; tuberculous pleuritis, 30% +/- 7%) than in those with ineffective immunity (advanced pulmonary tuberculosis, 9% +/- 3%; miliary tuberculosis, 2% +/- 1%). In leprosy, expansion of gamma delta+ cells was greater in immunologically resistant tuberculoid patients (32% +/- 4%) than in Mycobacterium leprae-unresponsive lepromatous patients (9% +/- 2%). M. tuberculosis-reactive gamma delta T cell lines produced interferon-gamma, granulocyte-macrophage colony-stimulating factor, interleukin-3, and tumor necrosis factor-alpha, cytokines that activate macrophages and may contribute to mycobacterial elimination. These findings suggest that gamma delta T cells contribute to immune resistance against M. tuberculosis.

Cell Line↗
PubMed1992

Selective expansion of V delta 1 + T cells from leprosy skin lesions.

T cells bearing gamma delta T-cell receptors (TCRs) are prominent residents of murine epidermis and appear to be important participants in the immune response to infection in human skin. The Mitsuda reaction in leprosy, induced by intradermal challenge with Mycobacterium leprae, provides an opportunity to study the cellular events that mediate a form of delayed-type hypersensitivity (DTH) in skin. T cells bearing gamma delta TCRs comprise a significant proportion of the T-cell population in these DTH reactions. Presently we have generated T-cell lines from Mitsuda reactions in vitro and compared their TCR repertoire to that found in situ. gamma delta T cells comprised 20-40% of lines derived from these skin lesions, but < 10% of lines derived from the peripheral blood of the same individuals. Flow-cytometric analysis of variable (V) chain usage in T-cell lines derived from skin lesions indicated that V delta 1 was predominant. Evaluation of the TCR repertoire using PCR indicated that V delta 1-J delta 1 and V gamma 2-J gamma P gene rearrangements were prevalent. In comparison, V delta 2-J delta 1 gene rearrangements predominated in situ. Furthermore, nucleotide sequence analysis of the V-J junction of one T-cell line revealed limited genetic diversity of the gamma delta TCR. These findings suggest that the V delta 1 subpopulation of gamma delta T cells in Mitsuda skin reactions selectively outgrows from leprosy skin lesions in vitro. Such V delta 1 + T-cell lines should be useful for determining the relevant antigens and restriction elements in this response to a pathogen in skin.

Amino Acid Sequence↗
PubMed1992

Limited T-cell receptor beta-chain diversity of a T-helper cell type 1-like response to Mycobacterium leprae.

Delayed-type hypersensitivity (DTH) is the standard measure of T-cell responsiveness to infectious organisms. For leprosy, the Mitsuda reaction, a local immune response to cutaneous challenge with Mycobacterium leprae, is considered to represent a measure of DTH against the pathogen. We analyzed the diversity of the T-cell receptor beta-chain repertoire in Mitsuda reactions to determine the breadth of the mycobacterial antigens involved. The polymerase chain reaction was used to compare V beta usage in the Mitsuda reaction T-cell lines established and unstimulated peripheral blood. These molecular analyses revealed a skewed T-cell receptor V beta gene usage in the Mitsuda reaction and in T-cell lines from lesions. To examine the reactivity of T cells from these lesions, T-cell lines were tested against the available native and recombinant antigens of M. leprae. T-cell lines derived from Mitsuda reactions responded more strongly to the 10-kDa M. leprae antigen, a homolog of GroES in Escherichia coli, than to other M. leprae proteins. T-cell lines were also shown to proliferate strongly in response to the 17- and 3-kDa proteins. The pattern of the lymphokine mRNA of these cells was reminiscent of the pattern of murine TH1 cells, positive for interleukin-2 and gamma interferon and weakly positive for interleukin-4. These data indicate that a limited array of T cells, perhaps recognizing stress proteins, secrete a type 1 lymphokine profile in the DTH response to mycobacteria.

Antigens, Bacterial↗
PubMed1992

Tumor necrosis factor production in patients with leprosy.

The spectrum of host responses to Mycobacterium leprae provides a model for investigating the role of cytokines in the pathogenesis of mycobacterial disease. Of particular interest is tumor necrosis factor (TNF), a cytokine which may have both antimycobacterial and immunopathologic effects. To evaluate the potential role of TNF in leprosy, we measured TNF production in response to M. leprae and its defined constituents by peripheral blood mononuclear cells from patients across the spectrum of disease. The levels of TNF induced through the stimulation of cells with M. leprae or its dominant "lipopolysaccharide," lipoarabinomannan, were higher in patients with the tuberculoid form of the disease than in those with the lepromatous form. In patients with erythema nodosum leprosum (ENL), a reactional state of lepromatous leprosy, the levels of TNF release by peripheral blood mononuclear cells were higher than in any other form of the disease. Treatment of ENL patients with thalidomide reduced TNF secretion by more than 90%. The mycolylarabinogalactan-peptidoglycan complex of Mycobacterium species, the protein-peptidoglycan complex, and muramyl dipeptide all elicited significant TNF release. Therefore, TNF release appears to be triggered by at least two major cell wall structural constituents of M. leprae, lipoarabinomannan and segments of the cell wall skeleton. The prominent TNF release in patients with the paucibacillary tuberculoid form of the disease compared with that in patients with the multibacillary lepromatous form suggests that this cytokine contributes to a resistant immune response to mycobacterial infection. However, the marked TNF release in patients with ENL indicates that TNF may also mediate immunopathologic effects, such as fever and tissue damage.

Antigens, Bacterial↗
PubMed1992

Stigma variations: observations on suppressor T cells and leprosy.

Few areas of immunology have been so controversial as that of suppressor T cells. Studies of T cell clones derived from patients with infectious diseases, including leprosy, and allergies have allowed the delineation of functional human T cell subsets. Both CD4 and CD8 cells can be discriminated into subsets that are differentiated by their functions and patterns of lymphokines. Type 1 CD4 cells reactive with lepromin and PPD produce IFN-gamma and IL-2 predominantly, while Type 2 CD4 clones, specific for tetanus toxoid, produce IL-4 and IL-5. Type 1 CD8 cytotoxic T lymphocytes produce predominantly IFN-gamma and IL-2. T suppressor clones derived from immunologically unresponsive lepromatous leprosy patients are antigen-specific, CD8 cells, HLA-DQ restricted, and produce predominantly IL-4, and were designated Type 2 CD8 cells. Several models for peripheral tolerance based on distinct functional T cell subsets are discussed. Previous models of T cell suppression in the mouse and the reciprocal relationship between humoral and cell-mediated immunity in general are reinterpreted in light of such T cell subset interactions.

Animals↗
PubMed1991

The T cell receptors of human gamma delta T cells reactive to Mycobacterium tuberculosis are encoded by specific V genes but diverse V-J junctions.

The observation that gamma delta T lymphocytes react to mycobacteria has provided an important model for investigation of these cells in the immune response to infection. One important question regarding human gamma delta T cells is the breadth of the T cell repertoire in response to specific pathogens. The present study was undertaken to characterize, in molecular terms, the mycobacterium-specific gamma delta TCR repertoire. Mononuclear cells were isolated from the peripheral blood and pleural fluid of patients with tuberculous pleuritis and stimulated with Mycobacterium tuberculosis in vitro. Cytofluorometric analysis of the expressed gamma delta TCR repertoire of M. tuberculosis expanded cells was performed using anti-V region antibodies. The majority of responding gamma delta T cells express a receptor composed of V delta 2 and V gamma 9 chains. Molecular analysis by PCR amplification confirmed use of the V delta 2 and V gamma 9 gene segments in these cells, and demonstrated predominant usage of J delta 1 and J gamma P gene segments. Analysis of nucleotide sequence at the V-J junctions revealed extensive diversity including nucleotide deletions of V, D, and J gene segments and nucleotide segment additions. The predicted amino acid sequences further indicates diversity in the V-J encoded region of the protein chains. The data indicate that M. tuberculosis-driven expansion of gamma delta T cells in vitro depends on specific pairing of the V delta 2 and V gamma 9 polypeptide chains, without apparent selection of explicit V-J junction regions.

Amino Acid Sequence↗
PubMed1991

A predominance of the T cell receptor V gamma 2/V delta 2 subset in human mycobacteria-responsive T cells suggests germline gene encoded recognition.

Little is known about the nature of Ag recognition by the TCR-gamma delta. The recent observation that gamma delta T cells preferentially recognize mycobacterial Ag provides a model to examine the molecular basis of gamma delta-TCR recognition. Here, examination of the Mycobacteria-stimulated peripheral blood T cells with TCR-specific mAb revealed a predominance of T cells bearing V gamma 2/V delta 2 gene products. PCR cloning and sequence analysis of the TCR chains demonstrated extensive junctional diversity indicating that the response was polyclonal. The marked in vitro gamma delta T cell response to Mycobacteria was also detected in newborns before encounters with foreign Ag and exclusively involved the same V-gene usage observed in adults. Together, these results suggest that a major mechanism of gamma delta T cell reactivity involves recognition mediated by germline-encoded segments of the TCR.

Adult↗
PubMed1991

Defining protective responses to pathogens: cytokine profiles in leprosy lesions.

The immunological mechanisms required to engender resistance have been defined in few infectious diseases of man, and the role of specific cytokines is unclear. Leprosy presents clinically as a spectrum in which resistance correlates with cell-mediated immunity to the pathogen. To assess in situ cytokine patterns, messenger RNA extracted from leprosy skin biopsy specimens was amplified by the polymerase chain reaction with 14 cytokine-specific primers. In lesions of the resistant form of the disease, messenger RNAs coding for interleukin-2 and interferon-gamma were most evident. In contrast, messenger RNAs for interleukin-4, interleukin-5, and interleukin-10 predominated in the multibacillary form. Thus, resistance and susceptibility were correlated with distinct patterns of cytokine production.

Base Sequence↗
PubMed1991

Differing lymphokine profiles of functional subsets of human CD4 and CD8 T cell clones.

Functional subsets of human T cells were delineated by analyzing patterns of lymphokines produced by clones from individuals with leprosy and by T cell clones of known function. CD4 clones from individuals with strong cell-mediated immunity produced predominantly interferon-gamma, whereas those clones that enhanced antibody formation produced interleukin-4. CD8 cytotoxic T cells secreted interferon-gamma. Interleukin-4 was produced by CD8 T suppressor clones from immunologically unresponsive individuals with leprosy and was found to be necessary for suppression in vitro. Both the classic reciprocal relation between antibody formation and cell-mediated immunity and resistance or susceptibility to certain infections may be explained by T cell subsets differing in patterns of lymphokine production.

Antibody Formation↗
PubMed1991

Gamma/delta T cell receptor positive T cells in the inflammatory joint: lack of association with response to soluble antigens.

In patients with inflammatory synovitis, the proliferative response by lymphocytes from synovial fluid to soluble mycobacterial antigens is enhanced relative to those from peripheral blood. Earlier studies suggested that gamma/delta T cell receptor positive (TCR+) T lymphocytes may significantly contribute to the mycobacterial-specific synovial fluid response. We therefore examined the relationship of the T cell proliferative response to Mycobacterium tuberculosis antigens and the presence of gamma/delta TCR+ T cells employing several monoclonal antibodies. No consistent increase of gamma/delta TCR+ T cells was noted in inflammatory synovial fluids or tissues. Nonetheless, lymphocytes from the majority of the synovial fluids proliferated vigorously in response to water-soluble M. tuberculosis antigens. There was no relationship between the percentage of gamma/delta TCR+ T lymphocytes and the intensity of the proliferative response. In contrast, stimulation with whole mycobacterial organisms was capable of enriching the gamma/delta TCR+ cell population obtained from the peripheral blood of tuberculosis skin test positive normal controls and from some inflammatory synovial fluids. These observations do not support a role for mycobacteria reactive gamma/delta TCR+ synovial T lymphocytes in response to soluble mycobacterial antigens or in the local pathogenesis of inflammatory synovitis.

Antigens, Bacterial↗
PubMed1991

Evidence for clonal selection of gamma/delta T cells in response to a human pathogen.

T cells bearing gamma/delta antigen receptors comprise a resident population of intraepithelial lymphocytes in organs such as skin, gut, and lungs, where they are strategically located to contribute to the initial defense against infection. An important unsolved question about antigen-driven gamma/delta T cell responses regards the breadth of their T cell receptor (TCR) repertoire, since many specific epithelial compartments in mice display limited diversity. We have examined the diversity of TCR delta gene expression among human gamma/delta T cells from skin lesions induced by intradermal challenge with Mycobacterium leprae. We show that the vast majority of gamma/delta cells from M. leprae lesions use either V delta 1-J delta 1 or V delta 2-J delta 1 gene rearrangements and, within a given region of the lesion, display limited junctional diversity. This contrasts markedly with the extensive diversity of gamma/delta T cells from peripheral blood of these same individuals, as well as skin from normal donors. These results indicate that the gamma/delta response to M. leprae involves the selection of a limited number of clones from among a diverse repertoire, probably in response to specific mycobacterial and/or host antigens.

Amino Acid Sequence↗