# VITAMIN D METABOLISM BY T CELL LYMPHOCYTES

> **NIH NIH R01** · UNIVERSITY OF TEXAS HLTH SCIENCE CENTER · 1987 · $65,712

## Abstract

The purpose of this project is to characterize the metabolism of vitamin D
by T-cell lymphocytes in vitro with particular attention to the production
of 1,25-dihydroxyvitamin D (1,25(OH)2D), the most active metabolite of
vitamin D.  Preliminary results from the Principal Investigator's
laboratory indicate that HTLV-transformed cord blood lymphocytes have the
capacity to convert 25(OH)D to a more polar metabolite which coelutes with
authentic 1,25(OH)2D using two separate high performance liquid
chromatography systems and stimulates bone resorption in vitro.
Identification of this metabolite as 1,25(OH)2D by gas chromatography/mass
spectrometry suggest that these transformed lymphocytes have
1-alpha-hydroxylase activity.  Since 1,25(OH)2D is a potent stimulator of
osteoclastic bone resorption, increased production of 1,25(OH)2D or other
vitamin D metabolites by lymphoma cells may play a role in the pathogenesis
of the increased osteoclastic bone resorption and hypercalcemia which occur
in this disease.

Accordingly, the purpose of this study is to use HTLV-transformed
lymphocytes as an in vitro model to study the metabolism of vitamin D by
lymphocytes in order to:

1. Characterize the metabolites of vitamin D which are produced by HTLV
transformed T-lymphocytes with particular attention to the production of
1,25(OH)2D.

2. Examine the metabolism of vitamin D by peripheral lymphocytes in
patients with other disease states characterized by abnormal lymphocyte
function and altered bone and mineral metabolism.

3. Determine if activated normal lymphocytes have 1-alpha-hydroxylase
activity.

4. Characterize the 1-alpha-hydroxylase activity in normal and abnormal
lymphocytes to see if it is regulated by the same factors which regulate
renal 1-alpha-hydroxylase activity.

These studies will determine whether or not the ability to produce
1,25(OH)2D is a general property of all activated lymphocytes or is a
unique property of lymphocytes infected with the HTLV virus.  Moreover,
characterization of this 1-alpha-hydroxylase activity and identification of
those factors which regulate lymphocyte 1-alpha-hydroxylase activity will
provide important information concerning factors that control vitamin D
metabolism both in normal individuals and disease states characterized by
abnormal bone and mineral metabolism.  These results will also form the
basis of studies designed to elucidate the molecular mechanisms responsible
for the activation of 1-alpha-hydroxylase activity in lymphocytes.

## Key facts

- **NIH application ID:** 3157353
- **Project number:** 5R01AR035762-02
- **Recipient organization:** UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
- **SAM.gov UEI:** C3KXNLTAAY98
- **Principal Investigator:** JAMES F DUNN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1987
- **Award amount:** $65,712
- **Award type:** 5
- **Project period:** 1986-04-01 → 1989-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3157353

## Citation

> US National Institutes of Health, RePORTER application 3157353, VITAMIN D METABOLISM BY T CELL LYMPHOCYTES (5R01AR035762-02). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3157353. Licensed CC0.

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