Effect of active vitamin D3 on age-related immunological changes

Immune dysfunction in hypophosphatemic vitamin D-resistant rickets: immunoregulatory reaction of 1 alpha(OH) vitamin D3

We investigated immunologic function in six cases with hypophosphatemic vitamin D-resistant rickets (VDRR) before and after treatment with 1 alpha-hydroxycholecalciferol (1 alpha(OH) vitamin D3). All cases suffered frequent episodes of infection, which tended to be more severe in the older patients. OKT9-, OKT10-, and OKM1-positive cells and adenosine deaminase (ADA) were significantly increased, whereas numbers and activity of natural killer (NK) cells were lower than normal before treatment. After administration of 1 alpha(OH) vitamin D3, however, the susceptibility to infection apparently decreased, and NK cell number and activity increased in all patients. ADA was also significantly decreased and remained in the normal range after treatment. These results suggest that vitamin D plays a role in the impaired immunoregulatory functions of NK cells in VDRR. Furthermore, ADA may be one parameter reflecting this immunologic impairment.

Inhibitors of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced multinucleated cell formation and HTLV-I p19 antigen expression in HTLV-I-infected T-cell line KH-2Lo

To elucidate the biological mechanisms of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced phenotypic changes in HTLV-I virus-infected human T-cell line KH-2Lo cells, inhibitors of TPA-induced ornithine decarboxylase (ODC), protein kinases and calmodulin were examined for their effects on TPA-induced multinucleated cell formation and HTLV-I p19 antigen expression. Among the inhibitors of TPA-induced ODC activity, alpha-difluoromethyl ornithine (DFMO), 1,25(OH)2D3 and its analogues, and retinoic acid were tested. As inhibitors of protein kinases, 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7), N-[2-(methylamino)ethyl]-5-isoquinoline-sulfonamide (H-8) and 1,(5-isoquinolynylsulfonyl)-2,3-dimethylpiperazine (H-5) were used. In addition, a calmodulin inhibitor, N-(4-aminobutyl)-5-chlor-2-naphthalenesulfonamide (W13) and its inactive analogue, N-(4-aminobutyl)-2-naphthalenesulfonamide (W12) were also tested. 1,25(OH)2D3 and its active analogues inhibited both TPA-induced HTLV-I p19 antigen expression and multinucleated cell formation after 4 days of culture with TPA. On the other hand, an inhibitor of ODC, DFMO, the protein kinase inhibitors, the calmodulin inhibitor and retinoic acid suppressed TPA-induced HTLV-I p19 expression but did not suppress multinucleated cell formation.