Characterization of a 10- to 14-kilodalton protease-sensitive Mycobacterium tuberculosis H37Ra antigen that stimulates human gamma delta T cells.

Abstract

gamma delta T-cell receptor-bearing T cells (gamma delta T cells) are readily activated by intracellular bacterial pathogens such as Mycobacterium tuberculosis. The bacterial antigens responsible for gamma delta T-cell activation remain poorly characterized. We have found that heat treatment of live M. tuberculosis bacilli released into the supernatant an antigen which stimulated human gamma delta T cells. gamma delta T-cell activation was measured by determining the increase in percentage of gamma delta T cells by flow cytometry in peripheral blood mononuclear cells stimulated with antigen and by proliferation of gamma delta T-cell lines with monocytes as antigen-presenting cells. Supernatant from heat-treated M. tuberculosis was fractionated by fast-performance liquid chromatography (FPLC) on a Superose 12 column. Maximal gamma delta T-cell activation was measured for a fraction of 10 to 14 kDa. Separation of the supernatant by preparative isoelectric focusing demonstrated peak activity at a pI of < 4.0. On two-dimensional gel electrophoresis, the 10- to 14-kDa FPLC fraction contained at least seven distinct molecules, of which two had a pI of < 4.5. Protease treatment reduced the bioactivity of the 10- to 14-kDa FPLC fraction for both resting and activated gamma delta T cells. Murine antibodies raised to the 10- to 14-kDa fraction reacted by enzyme-linked immunosorbent assay with antigens of 10 to 14 kDa in lysate of M. tuberculosis. In addition, gamma delta T cells proliferated in response to an antigen of 10 to 14 kDa present in M. tuberculosis lysate. gamma delta T-cell-stimulating antigen was not found in culture filtrate of M. tuberculosis but was associated with the bacterial pellet and lysate of M. tuberculosis. These results provide a preliminary characterization of a 10- to 14-kDa, cell-associated, heat-stable, low-pI protein antigen of M. tuberculosis which is a major stimulus for human gamma delta T cells.

• Authors: W H Boom, K N Balaji, R Nayak, K Tsukaguchi, K A Chervenak
• Journal: Infection and immunity (Infect Immun) Vol. 62 Issue 12 Pg. 5511-8 (Dec 1994) ISSN: 0019-9567 [Print] United States
• PMID: 7960133 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antigens, Bacterial
• Receptors, Antigen, T-Cell, gamma-delta
• Pronase

Topics

• Antigens, Bacterial (immunology)
• Cytosol (immunology)
• Flow Cytometry
• Hot Temperature
• Humans
• Isoelectric Point
• Lymphocyte Activation (immunology)
• Molecular Weight
• Mycobacterium tuberculosis (classification, immunology)
• Pronase (metabolism)
• Receptors, Antigen, T-Cell, gamma-delta (immunology)
• T-Lymphocytes (immunology)