Duration of skin photosensitivity and incidence of photosensitivity reactions after administration of verteporfin

BACKGROUND: Verteporfin (Visudyne, Novartis AG) is a light-activated drug that reduces the risk of vision loss in patients with certain types of choroidal neovascularization (CNV). Because photosensitivity can occur with photosensitizers, it is important for ophthalmologists providing verteporfin therapy to understand its time course and duration, as well as the incidence of photosensitivity reactions. METHODS: Data were obtained from three sources: 1) the time course of skin photosensitivity in 17 volunteers by measuring erythema/edema over time after verteporfin, using red light exposure; 2) the duration of skin photosensitivity in 30 patients with skin cancer by exposing skin to simulated solar light and calculating the daily minimal erythematous dose; and 3) the incidences of photosensitivity reactions as recorded in three phase III trials in patients with CNV secondary to age-related macular degeneration or pathologic myopia who received the regimen of verteporfin therapy currently approved by regulatory authorities (infusion of 6 mg/m(2) body surface area). RESULTS: 1) Skin photosensitivity was high at the first timepoint of 1.5 hours after dosing and decreased rapidly thereafter; 2) the duration of skin photosensitivity was dose dependent, ranging from 2.0 to 6.7 days at 6 to 20 mg/m(2), respectively (mean of 2 days at a dose of 6 mg/m(2)); and 3) photosensitivity reactions occurred in only 2.2% of patients in the phase III trials, including two severe events, one secondary to extravasation. All treatment-related reactions in the phase III trials occurred within the first 2 days after dosing, with the exception of two mild reactions and one moderate reaction that occurred 3 days after treatment. CONCLUSIONS: Verteporfin is associated with short-lived photosensitivity and a low incidence of photosensitivity reactions in clinical trials, most of which could probably have been avoided by adherence to protocol instructions for skin protection.     

Cells involved in the immune response: XXII. The demonstration of thymus-specific antigens in the rabbit

Horse anti-rabbit thymus cell serum (HARTS) was obtained by immunizing a horse with rabbit thymocytes intravenously at weekly intervals for 3 weeks. The horse was bled 2 weeks later and the antiserum was analysed for its cytotoxic activity with respect to the lymphocytes of the various lymphoid organs. It was demonstrated that the cytotoxic activity of the antiserum was several orders of magnitude greater for thymus cells than for cells of the other organs tested. Only thymus and lymph node cells were capable of absorbing the thymocytotoxic activity of the antiserum; however, ten to fifteen times as many lymph node cells as thymus cells were required to neutralize the thymocytotoxic activity of the serum. Absorption of the antiserum with the cells of the other lymphoid organs (spleen, bone marrow, appendix, sacculus rotundus, Peyer's patches and circulating leucocytes) resulted in a slight but significant decrease in the thymocytotoxic activity. At no time was the thymocytotoxic activity completely absorbed with cells of these organs. The cytotoxic activity of the antiserum with respect to the cells of the different lymphoid organs other than the thymus could be abolished following absorption of the antiserum with the cells of any of the lymphoid organs. On the basis of our data, it is concluded that (a) the thymocytes possess two groups of antigens—one thymocyte specific and one common to all rabbit lymphocytes and (b) only the lymph nodes of all the lymphoid organs other than the thymus possess significant numbers of thymus-derived or T-cells. However, the proportion of these cells in the lymph node does not exceed 7–10 per cent, a figure much lower than that found in the lymph nodes of the mouse. Less than 1 per cent of the circulating lymphocytes in the rabbit are T-cells.     

Antigenic Diversity of Hepatitis B Virus Strains of Genotype F in Amerindians and Other Population Groups from Venezuela

The adw4 subtype of hepatitis B virus (HBV) belongs to a unique genomic group (genotype F) representing the original HBV strains from the New World. Data regarding the prevalence of this subtype among HBV carriers in South America are, however, scarce, and those concerning HBV genotype F are based on only a few samples from Latin America. In this study, serum samples were obtained from 141 hepatitis B surface antigen (HBsAg) carriers from Amerindians and urban populations from Venezuela. The HBsAg subtype was identified with monoclonal antibodies in 105 samples, and the HBV genotype was identified by reverse-phase hybridization with DNA fragments in 58 samples. The adw4 subtype was highly prevalent in the population studied (75%); among the Amerindians, the prevalence was 97%. The adw2 subtype was also present (10%), while other subtypes (ayw3 and ayw4) were only occasionally found. The HBV subtype was associated with the expected genotype in most cases (80%), and thus genotype F was highly prevalent. Sequencing of viral strains that gave genotypes unpredicted by the HBsAg subtyping confirmed seven of them as belonging to not previously described genotype-subtype associations: namely, adw2 and ayw4 within genotype F.     

Intrasinusoidal cytotoxic CD8+ T cells in nodular regenerative hyperplasia of the liver

Diffuse nodular regenerative hyperplasia (NRH) of the liver is an acquired architectural disturbance that can lead to portal hypertension. Although frequently associated with autoimmune or hematologic malignancies, its exact pathogenesis remains largely unknown. We observed CD8+ cytotoxic T cells in the liver sinusoids of 14 of 44 NRH patients and explored possible relationships between these lymphocytes and vascular damage. The immunophenotype of intrahepatic lymphocytes was determined using immunohistochemical analysis and endothelial injury using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method for apoptosis combined with endothelial cell labeling. Controls for the quantitative analysis of liver-infiltrating lymphocytes consisted of patients with chronic hepatitis C or normal liver (n = 13 and n = 6, respectively). Liver specimens from the 14 patients dislayed intrasinusoidal infiltrate composed of CD3+ and CD8+ lymphocytes, located near atrophic liver cell plates. Significantly more granzyme B+ and CD57+ lymphocytes were observed in NRH than chronic hepatitis C samples with quantitatively similar CD8+ infiltrates. Double-labeling revealed apoptotic endothelial sinusoidal cells in CD8+ T-cell-infiltrated areas in all NRH samples but never in chronic hepatitis C or normal livers. T-cell receptor rearrangement or immunoscope analysis suggested liver-specific polyclonal or oligoclonal T-cell expansions. Clinical and biological characteristics of the 14 patients were similar to those observed in the 30 patients with NRH devoid of lymphocytic infiltration. We report here that CD8+ cytotoxic T cells infiltrated the liver sinusoids of a high percentage (32%) of NRH patients and suggest that some NRH cases might result from chronic, cytotoxic CD8+ T-lymphocyte targeting of sinusoidal endothelial cells.     

The intracellular localization of two antigens after uptake in vivo by peritoneal macrophages from normal mice

Normal mouse macrophages, which had ingested ferritin labelled with fluorescein isothiocyanate and human serum albumin labelled with tetramethylrhodamine isothiocyanate in vivo, were fixed in formalin and embedded for electron microscopy. The examination of sections 1–2 μ thick and adjacent ultrathin sections showed that the yellow-green fluorescent droplets (due to ferritin-FITC) seen by fluorescence microscopy were in the same position as the ferritin-containing phagolysosomes as seen by electron microscopy.

Normal mouse macrophages, which had ingested ¹²⁵I-labelled human serum albumin ([¹²⁵I]HSA) and unlabelled ferritin, were investigated by electron microscopic autoradiography. Both antigens were found to be situated within the same lysosomes.

     

Cells involved in the immune response: XXVI. The demonstration of bone-marrow specific antigens in the rabbit

Horse anti-rabbit bone marrow cell antiserum was tested for its cytotoxic activity with respect to the lymphocytes of the various lymphoid organs. The unabsorbed antiserum was highly cytotoxic with respect to the circulating WBC and cells of the bone marrow and thymus but demonstrated low cytotoxic activity with respect to spleen, lymph node and SAPP cells (sacculus rotundus, appendix and Peyer's patches). However, following absorption with thymocytes, lymph node cells or SAPP cells, cytotoxic activity directed toward any of these cell types disappeared without affecting the cytotoxic activity with respect to bone marrow and circulating lymphocytes. On the other hand, bone marrow and spleen cells and circulating white blood cells were capable of absorbing out completely the cytotoxic activity directed toward these cells. On the basis of a comparison of efficiency of absorption of anti-bone marrow cell activity by cells of the different lymphoid organs and cytotoxicity assays of the absorbed antiserum, it is concluded that approximately 15–25 per cent of the spleen lymphocytes and 20–40 per cent of the circulating lymphocytes in the rabbit are bone marrow-derived cells. The other lymphoid organs do not normally appear to possess these cells.