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Relationship between adenosine deaminase and a human thymus leukemia antigen isolated from MOLT 4 cells
Abstract:
The relationship between adenosine deaminase (ADA) and a human membrane thymus leukemia (HTL) antigen-detected by an antithymocyte serum was explored. A freeze-thaw extract of the T-cell-derived cell line, MOLT 4, was applied to an immunoabsorbant column of a rabbit antiserum to calf ADA. The bound MOLT 4 ADA was eluted with 6 M urea. The recovered ADA had a specific activity of 490 mumol of adenosine deaminated per min per mg protein, and the yield was 32%. No HTL antigenic activity was detected in the purified ADA. In addition, no ADA activity was detected in the unbound fraction containing the HTL antigenic activity, supporting the conclusion that ADA and HTL antigen are independent molecules. Affinity-purified anti-calf ADA was not cytotoxic for several HTL antigen-positive cells, including thymocytes, MOLT 4, and thymus-derived acute leukemia lymphoblasts.
Insights
Adenosine deaminase (ADA) and human thymus leukemia (HTL) antigen are distinct molecules. Purified ADA showed no HTL antigenic activity, confirming their independence and aiding in understanding T-cell leukemia.
Area of Science:
- Immunology
- Biochemistry
- Cell Biology
Background:
- Investigating the molecular relationship between adenosine deaminase (ADA) and human thymus leukemia (HTL) antigen.
- Understanding the role of these molecules in T-cell differentiation and leukemia.
Purpose of the Study:
- To determine if adenosine deaminase (ADA) and human thymus leukemia (HTL) antigen are associated or independent entities.
- To characterize the biochemical and antigenic properties of ADA purified from T-cell lines.
Main Methods:
- Immunoabsorbent chromatography using rabbit anti-calf ADA antiserum to purify ADA from MOLT 4 cell line extract.
- Assay of enzymatic activity (ADA) and antigenic activity (HTL) in purified and unbound fractions.
- Cytotoxicity testing of affinity-purified anti-calf ADA on HTL antigen-positive cells.
Main Results:
- Purified ADA exhibited high specific activity (490 mumol/min/mg) with a 32% yield.
- No HTL antigenic activity was detected in purified ADA, and no ADA activity was found in the HTL-positive fraction.
- Anti-ADA antibodies were not cytotoxic to HTL antigen-positive cells, including thymocytes and leukemia cell lines.
Conclusions:
- Adenosine deaminase (ADA) and human thymus leukemia (HTL) antigen are distinct and independent molecules.
- These findings differentiate ADA from HTL antigen, providing insights into T-cell leukemia markers.
- The lack of cytotoxicity suggests distinct biological roles and potential therapeutic targets.