Extraction of Tissue Antigens for Functional Assays
Summary
A simple protocol for preparing extracts of human tissue to be used as a source of antigens in functional T-cell assays is described. This method allows T-cell responses to tissue-derived antigens to be measured in vitro.
Abstract
Many of the antigen targets of adaptive immune response, recognized by B and T cells, have not been defined 1. This is particularly true in autoimmune diseases and cancer2. Our aim is to investigate the antigens recognized by human T cells in the autoimmune disease type 1 diabetes 1,3,4,5. To analyze human T-cell responses against tissue where the antigens recognized by T cells are not identified we developed a method to extract protein antigens from human tissue in a format that is compatible with functional assays 6. Previously, T-cell responses to unpurified tissue extracts could not be measured because the extraction methods yield a lysate that contained detergents that were toxic to human peripheral blood mononuclear cells. Here we describe a protocol for extracting proteins from human tissues in a format that is not toxic to human T cells. The tissue is homogenized in a mixture of butan-1-ol, acetonitrile and water (BAW). The protein concentration in the tissue extract is measured and a known mass of protein is aliquoted into tubes. After extraction, the organic solvents are removed by lyophilization. Lyophilized tissue extracts can be stored until required. For use in assays of immune function, a suspension of immune cells, in appropriate culture media, can be added directly to the lyophilized extract. Cytokine production and proliferation by PBMC, in response to extracts prepared using this method, were readily measured. Hence, our method allows the rapid preparation of human tissue lysates that can be used as a source of antigens in the analysis of T-cell responses. We suggest that this method will facilitate the analysis of adaptive immune responses to tissues in transplantation, cancer and autoimmunity.
Protocol
Discussion
This protocol was developed because we wanted to generate an extract from human tissue that was free from toxic chemicals such as detergents. Specifically we have used it to prepare extracts of human tissue that can be used in assays of human immune function in vitro. Extracts prepared using this protocol can equally be reconstituted in any buffer and used for many biochemical analyses, such as western blotting or liquid chromatography. This makes this technique applicable to many downstream applications.
<…Divulgaciones
The authors have nothing to disclose.
Acknowledgements
This work is supported by grants from the Australian National Health and Medical Research Council (NHMRC #559007) and the Juvenile Diabetes Research Foundation (JDRF 4-2006-1025) and the Operational Infrastructure Scheme of the Victorian Government. We thank the members of the Tom Mandel Islet Transplantation Program Islet Isolation Team for providing the human tissues. Human tissues were collected and used with local ethical approval (St. Vincent’s Hospital HREC-A 011/04 and St. Vincent’s Health HREC-A 135/08).
Materials
| Name of the reagent | Company | Catalogue number | Comments |
| 5 ml 12 x 75 mm sterile polystyrene tubes | BD Falcon | 352054 | |
| Caps for tubes polystyrene tubes (above) | BD Falcon | 352032 | |
| 50ml sterile tubes | Becton Dickinson | 352070 | |
| Acetonitrile | Mallinckradt Chemicals | 2856-10 | |
| Butan-1-ol | Sigma Aldrich | 537993-IL | |
| Homogenizer: PRO200 | Bio-strategy | 01-01200 | 10 x 115 mm saw-tooth generator |
| Lyophilizer | Virtis, Benchtop 4K | ||
| Sterile Needle 18-20 gauge | Becton Dickinson | REF 302032 | |
| CMRL-1066 Medium | Sigma | C0422 | |
| PBS | Sigma | D8537 |
Table 1. Specific reagents and equipment.
Referencias
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