Minocycline-induced cutaneous hyperpigmentation: confocal laser scanning microscope analysis

BACKGROUND

Minocycline has a characteristic yellow-green fluorescent emission. This fluorescence has been previously demonstrated only in type 1 minocycline-induced skin hyperpigmentation.

OBJECTIVE

To investigate whether the fluorescence can be detected in other types of minocycline-induced cutaneous hyperpigmentation, and to study the possible mechanisms.

METHODS

Biopsies of pigmented and nonpigmented skin from 3 patients with different types of skin hyperpigmentation induced by minocycline were analysed by light microscopy and Confocal Laser Scanning Microscope (CLSM).

RESULTS

A yellow-green fluorescence was observed in the hyperpigmented skin of two patients with type 2, and one patient with type 4 minocycline-induced cutaneous hyperpigmentation. No fluorescence was detected in the non-pigmented skin.

CONCLUSION

Minocycline can possibly serve as a fluorescent probe in the diagnosis of all types of minocycline-induced cutaneous hyperpigmentation.

The effect of interferon-gamma and tumor necrosis factor-alpha on the expression of ICAM-1 and HLA-DR molecules on cells of a human germ cell neoplasm and their susceptibility to lysis by lymphokine-activated killer cells

The ICAM-1 molecule plays a role in the interaction of NK cells with a variety of tumor cells, including carcinoma, melanoma and glioblastoma cells. In the present study, we analyzed the effect of IFN-gamma and TNF-alpha on both the expression of HLA-DR and ICAM-1 molecules on HGCN (Germa-2), and on their susceptibility to lysis by LAK cells. Our results show that 1,000 U/ml IFN-gamma induced a substantial increase in the expression of both ICAM-1 molecules and HLA-DR on the cell surface, while the effect of TNF-alpha on the expression of these molecules was substantially less prominent. When Germa-2 cells, previously exposed to 1,000 U/ml IFN-gamma, were employed as target cells in a 4-hour 51Cr release assay, a statistically significant increase in the lysis by LAK cells was noted. These results show that in the presence of IFN-gamma, Germa-2 tumor cells undergo modulation which affects both the expression of ICAM-1 and HLA-DR molecules as well as their susceptibility to lysis by LAK cells.

Exposure of human peripheral blood mononuclear cells (PBMC) to hydrostatic pressure increases their proliferative response to phytohemagglutinin A (PHA) and anti-CD3 antibody

In the present study we show that a brief exposure of human PBMC to hydrostatic pressure (HyP) increased their proliferative response to PHA and anti-CD3 antibody, assessed by DNA synthesis. The effect of HyP was most prominent at 400 atmospheres of HyP followed by 600 and 200 atmospheres. At any pressure level, the highest effect of HyP was noted when employing PHA and anti-CD3 antibody at 10(-2) dilution. When PBMC were exposed to 400 atmospheres HyP, maximal effect was achieved at 20 minutes of exposure. The highest effect of HyP on DNA synthesis was noted at 48 and 72 hours of incubation with PHA, when exposing cells to pressure for 20 minutes at 400 atmospheres. Exposure of PBMC under similar conditions for 40 minutes, caused an increase in DNA synthesis only at 48 hours incubation with PHA. These results demonstrate that exposure of human PBMC to HyP increases their proliferative response to different polyclonal activators. The possible mechanisms involved in this phenomenon are discussed.