The rapid recognition of intravenously injected colloidal carriers, such as liposomes and polymeric nanospheres from the blood by Kupffer cells, has initiated a surge of development for "Kupffer cell-evading" or long-circulating particles. Such carriers have applications in vascular drug delivery and release, site-specific targeting (passive as well as active targeting), as well as transfusion medicine. In this article we have critically reviewed and assessed the rational approaches in the design as well as the biological performance of such constructs. For engineering and design of long-circulating carriers, we have taken a lead from nature. Here, we have explored the surface mechanisms, which affords red blood cells long-circulatory lives and the ability of specific microorganisms to evade macrophage recognition. Our analysis is then centered where such strategies have been translated and fabricated to design a wide range of particulate carriers (e.g., nanospheres, liposomes, micelles, oil-in-water emulsions) with prolonged circulation and/or target specificity. With regard to the targeting issues, attention is particularly focused on the importance of physiological barriers and disease states.

Long-Circulating and Target-Specific Nanoparticles: Theory to Practice

Dendritic cells: unique leukocyte populations which control the primary immune response.

Background: Some patients who have a total hip replacement with a second-generation metal-on-metal articulation have persistent or early recurrence of preoperative symptoms. Characteristic histological changes in the periprosthetic tissues suggested the development of an immunological response. Therefore, in order to determine the relevance of these symptoms, we performed a study of the clinical data and periprosthetic tissues associated with endoprostheses with a metal-on metal articulation that had been retrieved at revision.

Methods: Periprosthetic tissues as well as the clinical data on the patients were obtained from the first nineteen consecutive revisions performed at the treating hospitals. At the time of the revision, fourteen patients had the metal-on-metal articulation exchanged for either an alumina-ceramic or a metal-on-polyethylene articulation. Five patients received another second-generation metal-on-metal total joint replacement. Five-micrometer sections were prepared from the tissue samples, were stained with routine and immunohistochemical methods, and were examined histologically. Histological specimens from three groups of patients, two of which were treated with non-metal-on-metal implants, served as controls.

Results: The majority of patients had persistence of their preoperative pain or early recurrence of the pain after the original total hip replacement, and often a pronounced hip joint effusion had developed after the original replacement. Radiographic follow-up showed the development of radiolucent lines in five hips and of osteolysis in another seven hips. At the revision surgery, both the cup and the stem were found to be well fixed in nine patients. The characteristic histological features were diffuse and perivascular infiltrates of T and B lymphocytes and plasma cells, high endothelial venules, massive fibrin exudation, accumulation of macrophages with droplike inclusions, and infiltrates of eosinophilic granulocytes and necrosis. Only a few metal particles were detected. Immunohistochemical analysis demonstrated that the cellular reaction was still active. The patients who received another second-generation metal-on-metal articulation at the time of the revision had no decrease in symptoms. In the control group of tissues obtained at revisions of endoprostheses without cobalt, chromium, or nickel articulations, there were no similar signs of immune reactions.

Conclusions: These histological findings support the possibility of a lymphocyte-dominated immunological response. Although the prevalence of this reaction is low, the persistence or early reappearance of symptoms, including a marked joint effusion and the development of osteolysis, after primary implantation may suggest the possibility of such a reaction.

Metal-on-metal bearings and hypersensitivity in patients with artificial hip joints. A clinical and histomorphological study.

The catechol-O-methyltransferase polymorphism: relations to the tonic-phasic dopamine hypothesis and neuropsychiatric phenotypes.

Catechol-o-methyltransferase, cognition, and psychosis: Val158Met and beyond.

The antigenic phenotype of human villous stromal macrophages (M phi s) from first and third trimester placentas was analyzed using a large number of monoclonal antibodies (MAbs) to monocyte (Mo)/M phi-associated cell membrane determinants The purpose of this study was to investigate M phi phenotypic heterogeneity to create a database for the correlation of M phi phenotype with specific immunologic functions The results showed that villous stromal mononuclear cells express many cell surface antigens found on Mo and M phi s and that they are morphologically diverse, ranging in appearance from classic Hofbauer cells to spindle-shaped cells with long cytoplasmic processes Villous stromal M phi s were the numerically dominant cell type in this structure and exhibited some major phenotypic differences from M phi s in other tissues Comparison of first- and third-trimester placentas revealed variation in antigen expression with increasing gestational age, in particular of class II major histocompatibility complex (MHC) determinants: HLA-DR and HLA-DP antigen density was low on first-trimester villous M phi s and much higher on third-trimester M phi s while HLA-DQ was undetectable in the first trimester but present on cells in third trimester placentas The CD1 (T6) antigen, found on Langerhans (LH) cells and cortical thymocytes, was detected on villous M phi s by two thirds of the MAbs directed against different epitopes on this determinant Furthermore, comparison with similar studies of lymphoid tissues showed that villous M phi s and dendritic cells share the expression of a number of other cell surface antigens Finally, it was shown that M phi s in first- and third-trimester villi exhibit strong reactivity with MAbs (Leu 3a,b) to the CD4 antigen that serves as the receptor for the human immunodeficiency virus (HIV), suggesting that these cells may be a portal of entry or reservoir for this virus in the fetuses of pregnant, HIV+ women

The phenotype of human placental macrophages and its variation with gestational age.

Macrophages (M phi s) are an important component of the immune response and mediate numerous other functions. Phenotypic and functional subsets of circulating monocytes have been described, but few similar studies have analyzed M phi s in human tissues. By use of immunohistochemical techniques and a large number of monoclonal antibodies, the presence and distribution of phenotypic subpopulations of M phi s and dendritic cells in human spleen were assessed. The results of this study show that different subsets of M phi s and dendritic cells are present in the spleen and that some of these occupy discrete microanatomic locations. In the red pulp (RP) certain groups of antigens are expressed by different proportions of uniformly distributed M phi s in the cords. On the other hand, some antigens are present on M phi s that form clusters of variable size within the red pulp. M phi s in the splenic marginal zone (MZ) share some antigens with red pulp M phi s, but in addition express CR3, Mo-2, 61D3, and 63D3. These antigens are found on only a few RP M phi s. MZ cells expressing one antigen shared with RP M phi s (Leu-3a,b) and one present largely on the MZ cells (63D3) form clusters around small vessels; these structures resemble the so-called splenic ellipsoids that may play a role in the trapping of circulating antigens. Phagocytic M phi s (tingible body M phi s) of the white pulp follicular germinal centers were also shown to differ from RP and MZ cels with respect to the expression of the antigens detected by anti-FcR, Leu-M3, Mo-2, 25F9, and anti-CR3. The unique topographical and surface antigenic features of dendritic cells were confirmed by this study. Furthermore, these cells were found to share a number of antigens with RP, MZ, and white pulp M phi s, which suggests that they may be derived from a common progenitor. The presence of phenotypic subpopulations and variation in distribution among human splenic phagocytic cells and dendritic cells may be indicative of functional specialization.

Human spleen contains phenotypic subsets of macrophages and dendritic cells that occupy discrete microanatomic locations.

Catechol-O-methyltransferase (COMT) was visualized in homogenates and subcellular fractions of rat tissues, including liver and brain, by gel electrophoresis, electrophoretic transfer of proteins to nitrocellulose (Western blotting), and immune fixation with antiserum to highly purified soluble rat liver COMT. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of all tissue homogenates examined revealed three major immune-specific proteins with apparent molecular weights 23,000, 26,000, and 66,000 (23K, 26K and 66K). Centrifugation of homogenates at 100,000 X g for 60 min resulted in the enrichment of the 26K species protein in the pellet whereas the 23K and 66K proteins were the predominant forms in the supernatant. The 66K protein appeared in variable amounts depending on the tissue being examined and the length of transfer of protein and is assumed to be an "aggregate" of the smaller form(s). The 26K protein was essentially the only immunoreactive species seen in a purified preparation of rat liver outer mitochondrial membrane. Isoelectric focusing (IEF) under denaturing conditions and two-dimensional gel electrophoresis of brain and liver fractions showed that the 23K protein was resolved into three bands of pI 5.1, 5.2, and 5.3, whereas the 26K protein had a pI of 6.2. Analysis of COMT activity in slices from nondenaturing IEF gels indicated that the pI 5.1-5.3 species are biologically active; the pI 6.2 species could not be detected under these conditions. COMT activity was demonstrated, however, in outer mitochondrial membranes from rat liver, which contain predominantly the 26K, pI 6.2 immunoreactive species. The major form of COMT in all rat tissues examined is "soluble" with an apparent Mr of 23K and a pI of 5.2. The nature of the modifications giving rise to pI 5.1 and 5.3 forms of this enzyme are not clear, nor is the relationship between the 23K and 26K forms. Further studies are needed to elucidate the relationship of immunoreactive forms of COMT to each other, their intracellular location, and their functional significance.

Soluble and particulate forms of rat catechol-O-methyltransferase distinguished by gel electrophoresis and immune fixation.

Monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) activities were measured in cells from children with autism (n = 5) and the Gilles de la Tourette syndrome (n = 5). Monoamine oxidase activities in cultured skin fibroblasts (type A) and platelets (type B) from the same individual were not correlated. COMT activities in fibroblasts and red blood cells showed a negative but not significant correlation (r = -0.42). Fibroblast MAO and COMT activities from patients were similar to values from controls matched for age, race, and sex. Increasing clinical severity of illness in both disorders, however, correlated significantly with higher fibroblast MAE activity. Cultured fibroblasts provide a means of measuring enzyme activities independently of the individual's current physiological and psychological state.

Monoamine oxidase and catechol-O-methyltransferase activities in cultured fibroblasts and blood cells from children with autism and the Gilles de la Tourette syndrome

Muriel Braverman

Papers

The phenotype of human placental macrophages and its variation with gestational age.

Human spleen contains phenotypic subsets of macrophages and dendritic cells that occupy discrete microanatomic locations.

Soluble and particulate forms of rat catechol-O-methyltransferase distinguished by gel electrophoresis and immune fixation.

Monoamine oxidase and catechol-O-methyltransferase activities in cultured fibroblasts and blood cells from children with autism and the Gilles de la Tourette syndrome

Macrophages (histiocytes) in various reactive and inflammatory conditions express different antigenic phenotypes.