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A 180-kilodalton protein from Mycobacterium tuberculosis defined by a human T cell clone
A A Wadee1, J D Cohen, A R Rabson
1South African Medical Research Council Human Cellular Immunology Unit, Department of Immunology, School of Pathology, Johannesburg.
Abstract:
A high molecular weight protein from Mycobacterium tuberculosis (M. tuberculosis) has been identified, that is recognized by peripheral blood mononuclear cells from several tuberculous patients and by a T cell clone derived from a patient with tuberculous pleurisy. Purification of this fraction demonstrated biological activity to reside in a 180-kDa protein component. This mycobacterial protein appears to exist in some, but not all mycobacteria as the clone reacts to M. tuberculosis, BCG M. kansasii, M. flavescens and M. fortuitum, but not to M. intracellulare, M. scrofulaceum or a variety of gram-positive or gram-negative bacteria, or to PPD. Specific anti-genic challenge of the T cell clone in the presence of irradiated antigen presenting cells results in proliferation and interleukin-2 (IL-2) production. Proliferation is restricted to HLA Class II antigens as antigenic recognition occurs only in the presence of either one of the two parental DR haplotypes. Peripheral blood mononuclear cells from several other patients with pulmonary tuberculosis also proliferate in response to this antigen, emphasizing the relevance of T cell cloning techniques in identifying important mycobacterial antigens.
Insights
Researchers identified a 180-kDa protein from Mycobacterium tuberculosis that triggers immune responses in tuberculosis patients. This specific antigen is crucial for developing new diagnostic tools and potential vaccines against tuberculosis.
Area of Science:
- Immunology
- Microbiology
- Molecular Biology
Background:
- Tuberculosis remains a significant global health challenge, necessitating the identification of novel antigens for diagnostic and therapeutic advancements.
- Understanding the specific mycobacterial components that elicit T cell responses is critical for effective tuberculosis control strategies.
Purpose of the Study:
- To identify and characterize a high molecular weight protein from Mycobacterium tuberculosis recognized by T cells from tuberculosis patients.
- To investigate the specificity and immune response characteristics of this identified mycobacterial antigen.
Main Methods:
- Purification of a 180-kDa protein fraction from Mycobacterium tuberculosis.
- T cell clone stimulation assays using the purified protein.
- Analysis of T cell proliferation and interleukin-2 (IL-2) production.
- HLA restriction analysis of antigen recognition.
Main Results:
- A 180-kDa protein from Mycobacterium tuberculosis was purified and shown to be biologically active.
- The identified antigen elicited proliferation and IL-2 production in a T cell clone and peripheral blood mononuclear cells from tuberculosis patients.
- Antigen recognition was restricted to HLA Class II (DR) antigens.
- The antigen demonstrated cross-reactivity with specific Mycobacterium species (M. tuberculosis, BCG, M. kansasii, M. flavescens, M. fortuitum) but not others or PPD.
Conclusions:
- A specific 180-kDa mycobacterial antigen has been identified that is recognized by T cells from tuberculosis patients.
- This antigen holds potential for the development of new diagnostic tools and immunotherapeutic strategies for tuberculosis.
- T cell cloning is a valuable technique for discovering clinically relevant mycobacterial antigens.