Advanced Targeting Systems announces the release of two reagents for immunological studies:
- Anti-Tac (Cat.# AB-18) – a monoclonal antibody to human CD25, the interleukin-2 receptor, and
- Anti-Tac-SAP (Cat.# IT-23) – the immunotoxin made by conjugation of anti-Tac to saporin.
These reagents add to the growing list of ATS products for use in studies of the hematopoietic systems. Other products include the anti-human and mouse macrophage immunotoxin (Mac-1-SAP, Cat.# IT-06) and the anti-rat and mouse T lymphocyte immunotoxin OX7- SAP (Cat.# IT-02).
The interleukin 2 receptor (IL-2r) is expressed on activated T lymphocytes and is important for the proliferation of T lymphocytes in response to antigen. The IL-2r is not detected on resting cells.1 Anti-Tac is able to prevent activation of T lymphocytes by antigen; apparently by binding to a newly available receptor and blocking IL-2 binding.2 It is reactive with activated and functionally mature human T cells.3 Figure 1 shows FACS analysis of the antibody bound to SR cells. This cell line is derived from the peripheral blood of a patient with mycosis fungoides. The cells express CD25 and respond to IL-2.
Immunotoxins made with an antibody to the IL-2r have been suggested for clinical use in the treatment of T cell leukemias and lymphomas.4 We at ATS believe that, as a research tool, this reagent is an important part of the toolbox. Anti-Tac immunotoxins have been shown to remove activated T lymphocytes in culture,5 and can be used to understand the role of this population in its various processes in the immune system. Figure 2 shows this immunotoxin against SR cells that express CD25. The immunotoxin is more than 100-fold more effective than saporin alone. Later this year we will introduce an anti-rat CD25 immunotoxin that will be useful for in vivo studies in animal models.
- Engleman EG, Benike C, Osborne B, Goldsby R, Wang W, Bradley SR, Richerson GB (1980) Functional characteristics of human T-cell subpopulations distinguished by a monoclonal antibody. Proc Natl Acad Sci USA 77:1607-1611.
- Depper JM, Leonard WJ, Robb RJ, Waldmann TA, Greene WC (1983) Blockade of the interleukin-2 receptor by anti-Tac antibody: inhibition of human lymphocyte activation. J Immunol 131:690-696.
- Uchiyama T, Broder S, Waldmann TA, Wang W, Bradley SR, Richerson GB (1981) A monoclonal antibody (anti-Tac) reactive with activated and functionally mature human T cells. I. Production of anti-Tac monoclonal antibody and distribution of Tac (+) cells. J Immunol 126:1393-1397.
- Schnell R, Vitetta E, Schindler J, Barth S, Winkler U, Borchmann P, Hansmann ML, Diehl V, Ghetie V, Engert A. (1998) Clinical trials with an anti-CD25 ricin A-chain experimental and immunotoxin (RFT5-SMPT-dgA) in Hodgkin’s lymphoma. Leuk Lymphoma 30(5-6):525-537.