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Expression of p35 in hairy leukemic cells from Japanese patients
Abstract:
Spiro and coworkers found a 35000 dalton membrane protein (p35) expressed abundantly in hairy cells of a subset of white, American patients with hairy cell leukemia. They subsequently identified p35 to be the human homologue of murine Ii, an electrophoretically invariant protein associated with Ia molecules. Using related analytical techniques, we have studied leukemic cells of two blood and one splenic samples from three Japanese patients with hairy cell leukemia and have demonstrated abundance of p35 in the splenic and one of the blood samples. The second blood sample was negative for p35 by our method of analysis, but the same hairy cells became positive for p35 at 2 months in culture and negative again at 4 months in culture. All 3 samples of this patient (fresh hairy cells and cultured cells at 2 and 4 months) remained consistently positive for Ia and for light chain-restricted immunoglobulin. Control cells from one each of acute lymphoblastic leukemia and Burkitt's lymphoma were negative for abundant p35 expression after culture as well as in the fresh state. One can conclude that the Japanese form of hairy cell leukemia, while varying in several distinct clinical and laboratory features from hairy cell leukemia in caucasians, is characterized also by abundant expression of p35 as seen in a subset of white patients. In addition, this expression of p35 is developed by hairy leukemic cells in culture initially but is lost upon longer term culture, in parallel with the level of tartrate-resistant acid phosphatase reactivity.
Insights
Japanese hairy cell leukemia shares abundant p35 protein expression with a subset of Caucasian patients. This protein, the human homologue of murine Ii, shows variable expression in cultured leukemic cells.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- Hairy cell leukemia (HCL) is a rare lymphoid leukemia.
- A 35,000 dalton membrane protein (p35), the human homologue of murine Ii, is found in a subset of Caucasian HCL patients.
- Clinical and laboratory features of HCL can vary between ethnic groups.
Purpose of the Study:
- To investigate the expression of p35 in Japanese patients with hairy cell leukemia.
- To compare p35 expression in Japanese HCL with Caucasian HCL.
- To analyze the in vitro expression dynamics of p35 in HCL cells.
Main Methods:
- Analysis of leukemic cells from Japanese HCL patients using analytical techniques.
- In vitro culture of hairy cells to assess p35 expression over time.
- Assessment of Ia and light chain-restricted immunoglobulin expression.
- Comparison with control cells from acute lymphoblastic leukemia and Burkitt's lymphoma.
Main Results:
- Abundant p35 expression was detected in splenic and one blood sample from Japanese HCL patients.
- One blood sample initially negative for p35 became positive after 2 months in culture and negative after 4 months.
- All samples remained positive for Ia and immunoglobulin.
- Control cells showed no abundant p35 expression.
Conclusions:
- The Japanese form of hairy cell leukemia is characterized by abundant p35 expression, similar to a subset of Caucasian patients.
- p35 expression in HCL cells is dynamic in culture, initially increasing and then decreasing.
- p35 expression changes in culture may correlate with tartrate-resistant acid phosphatase reactivity.