Phase I and pharmacokinetic study of photodynamic therapy for high-grade gliomas using a novel boronated porphyrin.

PURPOSE: To determine the recommended dose, toxicity profile, and pharmacokinetics of a novel boronated porphyrin (BOPP) for photodynamic therapy (PDT) of intracranial tumors. PATIENTS AND METHODS: BOPP was administered alone in increasing doses (0.25, 0.5, 1.0, 2.0, 4.0, or 8.0 mg/kg) preoperatively in patients with intracranial tumors undergoing postresection PDT until dose-limiting toxicity (DLT) was observed. RESULTS: Twenty-nine assessable patients with intracranial tumors received BOPP intravenously 24 hours before surgery. The recommended dose was 4 mg/kg. Dose escalation was limited by thrombocytopenia. The most common nonhematologic toxicity was skin photosensitivity. Pharmacokinetic parameters showed increased area under the plasma concentration-time curve and maximum concentration with increased dose. Tumor BOPP concentrations also increased with increased dose. CONCLUSION: BOPP at a dose of 4 mg/kg was well tolerated. DLT was thrombocytopenia, and photosensitivity was the only other toxicity of note. The efficacy of PDT using BOPP requires further exploration.

Alveolar macrophage immaturity in infants and young children.

Very little is known about alveolar macrophage (AM) immunological function in early childhood. Using nonbronchoscopic bronchoalveolar lavage (BAL), this study sought to compare the proportion, number, and function of AM between very young and older children. BAL fluid (BALF) leukocyte parameters were determined in 63 children, and data divided into 3 age groups: group 1 (<2 yrs), group 2 (> or =2-< or =5 yrs) and group 3 (> or =6-< or =17 years). In a further subgroup of children, AM function and immune receptor expression were assessed, and data categorized into two age groups: <2 yrs and > or =2 yrs of age. Compared to groups 2 and 3, the AM percentage in the BAL in group 1 was significantly increased (median: 98% versus 92% and 91%), as was the albumin-adjusted AM concentration. AM from children <2 yrs expressed less human leukocyte antigen (HLA)-DR (versus > or =2 yrs of age), were less effective in reducing nitro blue tetrazolium, and released less interleukin (IL)-1 and tumour necrosis factor on lipopolysaccharide stimulation. There was no difference in release of IL-6, expression of intercellular adhesion molecule-1 (CD54), and AM stimulation of allogeneic T-cells, between children <2 yrs and > or =2 yrs of age. It was concluded that the capacity of alveolar macrophage to stimulate T-cells is not enhanced in early childhood, and that immaturity of alveolar macrophage function may contribute to an increased susceptibility to respiratory infections in this age group.

Susceptibility of human monocytes to HIV type 1 infection in vitro is not dependent on their level of CD4 expression.

Monocytes from HIV-seronegative persons were analyzed for CD4 expression and susceptibility to infection with HIV-1 on the day of isolation and following 1, 2, and 7 days in culture. Although surface CD4 was readily detected on freshly isolated monocytes, these cells were relatively resistant to infection. After 1 to 2 days in culture, when surface expression of CD4 had decreased over 90% to near background levels, cells became susceptible to infection with HIV-1. CD4 expression on monocytes cultured for 7 days was more than four times higher than that on freshly isolated cells, and the cultured cells were fully permissive to infection. These observations suggest that the differing susceptibility of monocytes and monocyte-derived macrophages to infection with HIV-1 is not simply proportional to the level of surface CD4 expression.

Class II MHC antigen-positive macrophages from human placentae suppress strong MLR and CML reactions.

Placental adherent cells (PAC), derived by mild enzymic digestion of human placentae and adherence to plastic, were tested for their ability to suppress MLR and CML reactions. Stimulation of allogeneic T cells by cord blood mononuclear cells or by a strongly stimulatory B lymphoblastoid cell line were consistently inhibited by all PAC preparations tested. PAC were fractionated by Fc rosetting and Percoll gradients to produce a number of bands. Suppression correlated with the content of macrophages in each band and was strongest in band 5 which generally contained 94-100% macrophages. The suppressive effect was not inhibited by indomethacin. The possible role of macrophages in suppressing immune reactivity in the placenta is discussed.

Application of a novel immunization protocol to the production of monoclonal antibodies specific for macrophages in human placenta.

A monolayer depletion/adoptive immunization protocol that biased the immune response towards recognition of placental macrophage (pMO) antigens was established. BALB/c spleen cells immune to human pMO were adsorbed onto monolayers of the B-cell line QIMR-WIL. Monolayer-depleted or unfractionated cells were transferred to irradiated recipients, which subsequently were restimulated with pMO then killed for hybridoma production. Screening of hybridomas revealed an increased proportion of pMO-specific hybridomas following transfer and fusion of monolayer-depleted cells. Two monoclonal antibodies (mAb), L9 and L21, which were generated through application of this protocol, are described. L9 recognized an antigen on cells within the villi in sections of term placenta and freshly isolated pMO. With time in culture, expression of this antigen decreased markedly. Macrophages, but no other cell type, in placental cell suspensions expressed this antigen. L9 failed to react with any peripheral blood cells. Immunoprecipitation and SDS-PAGE analyses indicated that two proteins of molecular weight (MW) 40,000 and 43,000 were recognized by L9. Sections of term placenta and freshly isolated pMO failed to react with L21. After 2-3 days in culture, however, most macrophages expressed this antigen. L21 reacted weakly with peripheral monocytes and granulocytes but not other normal peripheral blood cells. Myeloid cell lines reacted strongly with this mAb only after activation with PMA. SDS-PAGE analyses of the L21 immunoprecipitate under non-reducing conditions revealed a single band of 61,000 MW, while two bands of 46,000 and 49,000 MW were detected under reducing conditions. Cellular distribution and molecular weight analyses indicated that the antigens recognized by these two mAb were apparently distinct from previously defined myeloid antigens.

Isolation of macrophages from human placenta.

Human placentae have been extracted with combinations of enzymes to optimize the release of mononuclear phagocytes. A mixture of trypsin-DNAase used in sequential extraction was found to provide the best yield of adherent cells which were stable in culture. The majority of adherent cells exhibited phagocytic function and expression of receptor for IgG-Fc (FcR). Subsequent studies established that these functions were co-expressed by the same cells. The FcR+ cells were also shown by immunofluorescence with monoclonal antibodies to display monocyte-macrophage distinctive antigens and class I and class II MHC antigens. The placenta has thus been shown to provide a rich source of class II-positive macrophages suitable for immunological studies.

Subject cooperation and the visual evoked response.

The effects on the visual evoked response (VER) of subject behavior, such as accuracy of fixation, stability of eye position, and degree of concentration, are poorly documented. Experiments were performed on 20 normal subjects to investigate the effects on the VER of eye movements, off-center stimulation, concentration on another task, and voluntary defocusing. It was found that there are some conditions under which a normal subject can produce an abnormal VER which could lead to misdiagnosis.