20α Hydroxysteroid Dehydrogenase (20αSDH) Activity in New Zealand Mice T Lymphocytes and Bone Marrow Cells: Effect of Age, Sex, and Castration

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Abstract
The activity of 20α hydroxysteroid dehydrogenase (20αSDH), a T lymphocyte-associated enzyme, was measured in fetal liver, thymus, spleen, and bone marrow cells from NZB, NZW, and (NZB × NZW)F1 (B/W) mice. There was an age-dependent increase of 20αSDH activity in bone marrow cells, and a decrease in thymocytes and splenic T lymphocytes. Treatment with anti-θ and complement did not reduce the 20αSDH activity of bone marrow and fetal liver cells, but reduced the activity of spleen cells. PHA stimulates both 20αSDH activity and thymidine incorporation in splenic, bone marrow, and fetal liver lymphocytes. The results suggest that the enzyme in the bone marrow and fetal liver is located in pre-T lymphocytes. Enzymatic activity in bone marrow cells taken from female B/W mice (older than 7 months) was 40 to 50% lower than in male mice. Orchidectomy, but not ovariectomy, caused a significant decrease in thymocyte 20αSDH activity. Orchidectomy depressed and ovariectomy enhanced 20αSDH activity of bone marrow cells. The 20αSDH activity of fetal liver cells from B/W mice was twice as high as in either parent strain. No 20αSDH activity was found in fetal liver cells taken from BALB/C SJL or C57BL/6 mice. A model is proposed to explain the age- and sex-related changes in 20αSDH activity of pre-T and T lymphocytes in healthy and pathologic conditions.