ß-Glucan and Parasites.

Immunosuppression caused by parasitic infections represents the foremost way by which the parasites overcome or escape the host's immune response. Glucan is a well-established natural immunomodulator with the ability to significantly improve immune system, from innate immunity to both branches of specific immunity. Our review is focused on the possible role of glucan's action in antiparasite therapies and vaccine strategies. We concluded that the established action of glucan opens a new window in treatment and protection against parasitic infections.

Soluble beta-glucan polysaccharide binding to the lectin site of neutrophil or natural killer cell complement receptor type 3 (CD11b/CD18) generates a primed state of the receptor capable of mediating cytotoxicity of iC3b-opsonized target cells.

When phagocyte CR3 binds to iC3b on bacteria or yeast, phagocytosis and degranulation are triggered because of simultaneous recognition of iC3b via a CD11b I-domain binding site and specific microbial polysaccharides via a lectin site located COOH-terminal to the I-domain. By contrast, when phagocyte or natural killer (NK) cell CR3 adheres to iC3b on erythrocytes or tumor cells that lack CR3-binding membrane polysaccharides, neither lysis nor cytotoxicity are stimulated. This investigation showed that soluble CR3-specific polysaccharides such as beta-glucan induced a primed state of CR3 that could trigger killing of iC3b-target cells that were otherwise resistant to cytotoxicity. Anti-CR3 added before sugars prevented priming, whereas anti-CR3 added after sugars blocked primed CR3 attachment to iC3b-targets. Polysaccharide priming required tyrosine kinase(s) and a magnesium-dependent conformational change of the I-domain that exposed the CBRM1/5 activation epitope. Unlike LPS or cytokines, polysaccharides did not up-regulate neutrophil CR3 expression nor expose the mAb 24 reporter epitope representing the high affinity ICAM-1-binding state. The current data apparently explain the mechanism of tumoricidal beta-glucans used for immunotherapy. These polysaccharides function through binding to phagocyte or NK cell CR3, priming the receptor for cytotoxicity of neoplastic tissues that are frequently targeted with iC3b and sparing normal tissues that lack iC3b.

Association of the leukemia inhibitory factor gene mutation and the antiphospholipid antibodies in the peripheral blood of infertile women.

To characterize the impact of the potentially functional mutation--the G to A transition at the position 3400 of the leukemia inhibitory factor (LIF; a pluripotent cytokine that plays a central role in the control of the embryo implantation) gene that leads to the exchange of valine with methionine at codon 64 we evaluated the association of the LIF gene mutation and the levels of antiphospolipid antibodies (aPLs) in the peripheral blood of infertile women (the aPLs examination was part of our routine immunological test during the infertility check-up). Eight infertile mutation-positive women were diagnosed with idiopathic infertility (n=5) and endometriosis (n=3) and their levels of aPLs in serum were compared with 115 infertile women without any LIF gene mutation. Enzyme-linked immunosorbent assay was used for the detection of seven antiphospholipid antibodies; the results were statistically assessed by the Fisher's 2 by 2 exact test to evaluate the association of the LIF gene mutations and aPLs in serum of infertile patients. The presence of aPLs was significantly higher in our study group (100%) than in 30% of aPLs-positives in control infertile patients (p = 0.0035) which indicates that the aPLs are elevated in women with LIF gene mutations.

Evolution of immune reactions.

The history and evolutionary pathways of defense reactions among various forms of life are reconstructed. The vertebrates evolved step-by-step from their invertebrate ancestors living in the distant past. The ancestry of vertebrate defense mechanisms must be traceable to them because these functions cannot be considered separately from the common evolutionary schema. The first part of this survey is therefore devoted to the description of major defense reactions and achievements in invertebrates. Particular emphasis is given to the taxa of present-day invertebrates most likely to exhibit some relationship to the chordates and thus to show real traces of vertebrate immune patterns. The second part involves three key assemblages of deuterostomate animals--the echinoderms, the nonvertebrate chordates, and the first vertebrates because these animals are believed to have created the prerequisites for transition from the invertebrate type of defense to the vertebrate type of adaptive immunity.

Enhanced phagocytic activity of blood leukocytes in athymic nude mice.

After 30-min incubation, blood leukocytes of adult athymic BALB/c nude mice (nu/nu) have a distinctly higher methacrylate or yeast particle uptake than leukocytes of euthymic nu/+ or +/+ mice. This permanent enhancement is not due to humoral factors, since the percentage of phagocytosing nu/nu leukocytes increases further in nu/+ littermate's plasma. Also, chronic infection or intraperitoneal immunization causes an additional transitory increase of the percentage of phagocytosing leukocytes and numbers of particles ingested; the phagocytic performance of leukocytes of euthymic mice is raised under these conditions by a greater factor. In fetuses enhanced phagocytosis of nu/nu mice is found only in monocytes. The bulk of ingestion of methacrylate particles is mediated by Fc receptors and significantly more receptors for IgG2B, IgG1, and IgG2A are demonstrable on nu/nu neutrophils; ingestion of particles via these receptors is again higher in nu/nu neutrophils, whereas nu/nu monocytes display a higher uptake via Fc(IgG1) receptors.

Possible role of procathepsin D in human cancer.

For the past ten years, our research has been focused on elucidating the mechanism by which procathepsin D (pCD) impacts cancer development. Various studies have shown that pCD is overexpressed and secreted by numerous cancer cell lines. After secretion, it exhibits "growth hormone-like" activity on cancerous cells but the exact mechanism of this mitogenic activity is not yet understood. The activation peptide of pCD (APpCD) (which is cleaved off upon activation of the zymogen) is responsible for the mitogenic function of pCD. Various in vitro and in vivo studies support our theory that the APpCD interacts with both parent and neighborhood cancer cells and thus functions as an autocrine mitogen. We propose a model of pCD mitogenic function and also some possible approaches for treatment and prevention of certain types of cancer.

Macrophages of athymic nude mice: Fc receptors, C receptors, phagocytic and pinocytic activities.

Expression of Fc receptors (FcR) for IgG1, IgG2A, IgG2B, IgM, IgA and IgE, binding of C3 and C5 complement components and phagocytic and pinocytic activities were determined in peritoneal and omental macrophages of nu/nu, nu/+ and +/+ Balb/c mice. nu/nu mice showed a higher proportion of FcR and complement receptor-bearing peritoneal macrophages along with a significantly higher phagocytic activity of peritoneal macrophages both in vitro and in vivo. Tests of pinocytic activity in these cells and phagocytic activity in omental phagocytes yielded similar results. We conclude that athymic mice compensate their immune defects by a higher phagocytic activity of their professional phagocytes and a higher expression of receptors mediating this process.

Effect of age on antibody responses in low responder C57BL/10ScSn and high responder A/J strains of mice.

The IgM antibody response to sheep red blood cells (SRBC) appeared significantly earlier in A/J strain mice (already in 10-day-old animals), but after 21 days responses were higher in B10 mice. These differences disappeared after reaching adulthood and IgM responses after either primary or secondary immunization were thereafter comparable in these strains. High-responder A/J mice made significantly more IgG antibodies than low-responder B10 mice from 21 days of age and strong differences lasted until the age of 19 months, when IgG antibody production was again similar. Potentiation of IgM formation by simultaneous application of 10 micrograms of LPS was higher in B10 mice until 19 months of age. On the other hand, potentiation of the IgG response was markedly high in B10 mice only in adult animals (3 months). Thereafter the potentiation was higher in A/J mice. The onset of Ig secretion in A/J mice was at 15 days and markedly increased at the age of 30 days. Levels of immunoglobulin synthesis remained extremely low in B10 mice. Age-related changes in IgG antibody production generally correlated with the decline of MHC class II antigen expression on peritoneal macrophages in these strains.

The potentiation of in vitro antibody response in low-responding mice by addition of cytokines.

The effect of exogenous cytokines on the antibody response to ARS-BGG after in vitro immunization in high- and low-responding strains of mice was determined. Twenty units/ml was established to be the optimal dose of cytokines. The low IgG antibody response to ARS-BGG in low-responding B10 mice was increased significantly by addition of either IL-4 or IFN-gamma. Similarly, the lower production of IgA antibodies was elevated by addition of either IL-2, IL-4, IL-5 or IFN-gamma. The levels of IgM were not influenced by any of the cytokines tested. Cytokines, therefore, play a fundamental role in regulating the responsiveness to protein antigen.

Effect of cytokines on 5-fluorouracil-mediated immunosuppression.

The effect of cytokines on 5-fluorouracil-mediated suppression of antibody response to arsanilic acid-bovine gammaglobulin (ARS-BGG) in high- and low-responding strains of mice was determined. Single i.v. injections of 5-fluorouracil strongly inhibited both primary and secondary antibody responses. The high-responding strain was found to be more sensitive to 5-fluorouracil. Restoration of suppressed IgG antibody responses to ARS-BGG was achieved in vitro by addition of either rIL-4, or rIFN gamma to the culture medium. Similarly, IgA titers recovered following the addition of exogenous rIL-5. The inhibition of IgM production, however, was not influenced by any of the cytokines tested. No significant differences were observed between experimental groups injected with antigen before or after 5-fluorouracil application. Our results suggest that the immunosuppression caused by 5-fluorouracil treatment can be abrogated by the addition of cytokines.

An advantageous method for detection of Fc-receptors and for studying Fc-receptor-mediated phagocytosis.

A method employing fluorescent 2-hydroxyethyl methacrylate copolymer particles with dinitrophenyl haptenic group and anti-haptenic murine monoclonal antibodies of different isotypes is described for tracing Fc-receptors and for studies of phagocytosis via these cell surface structures. The possibility of quenching the fluorescence of non-phagocytosed particles enables us to distinguish clearly and reliably between internalized and cell surface-bound particles.

Macrophage function in high- and low-responder strains of mice.

Unstimulated peritoneal macrophages of the high-responder A/J mice compared to the low-responder B10 strain have a lower number of cells with the different Fc receptor (FcR) subtypes and correspondingly the FcR mediated phagocytosis is also lower. The intraperitoneal immunization with SRBC leads to a prompt increase of FcR expression and of phagocytic and pinocytic activity in the A/J mice, while in the B10 strain the activity of macrophages remains unchanged.

In vitro antigen-binding properties of coelomocytes of Eisenia foetida (Annelida).

Annelids are capable of cellular and humoral defence reactions against foreign antigens. The main aim of this study was to characterise the antigen-binding properties of coelomocytes of Eisenia foetida by means of quantitative autoradiography and direct measurement of radioactivity. It was found that the antigen-binding capacity was significantly increased after antigen stimulation. Furthermore, the preincubation of coelomocytes with non-labelled proteins reduced the binding of radiolabelled antigen. The highest level of inhibition was found when the same protein was used for preincubation. These results indicate that antigen-binding properties are to some extent specific.

Phagocytic uptake of synthetic particles in blood leukocytes of fetal and newborn athymic nude mice.

Monocytes are the main phagocytic element in the blood of fetal mice; monocytes of athymic nude mouse fetuses (gestation days 17-20) ingest in vitro, in full blood, significantly more synthetic (HEMA) particles than the monocytes of their euthymic littermates. Blood leukocytes of athymic fetuses also bear much higher densities of Fc receptors for IgG2B. The differences in phagocytic uptake in blood leukocytes disappear and the differences in Fc(IgG2B) receptors decrease at postnatal days 2 and 4.

Alpha-fetoprotein and phagocytosis in athymic nude mice.

Alpha-fetoprotein (AFP) was found to suppress the phagocytic activity of the blood monocytes and neutrophils in vitro. The amounts of AFP detectable by immunofluorescence in the livers of nu/nu, nu/+ and +/+ mice were quite comparable, and thus could not have been responsible for the alterations in phagocytosis found in leukocytes of athymic nude mice during their ontogenetic development.

Subpopulations of circulating lymphocytes in adults with coeliac disease.

Circulating lymphocytes were enumerated in 25 patients with coeliac disease and in 24 healthy donors by immunofluorescent staining using monoclonal antibodies for T cell surface phenotypic markers T11 (mature), T4 (helper) and T8 (suppressor) or polyvalent antisera for surface immunoglobulins (B cells). Proportions of peripheral T and B cells and percentages and ratio of T cell subsets in coeliac disease were not significantly different from those in controls. Individual ratios of helper to suppressor T cells did not correlate with disease activity or with keeping the diet.

Phagocytosis of human blood leukocytes: a simple micromethod.

A simple micromethod for testing human blood leukocyte phagocytosis employing synthetic hydrophilic particles based on 2-hydroxyethylmethacrylate is described. The normal level of phagocytosing leukocytes in healthy children was 20.1 +/- 2.7%, and in healthy adult donors 34.3 +/- 6.1%. The method was found suitable for routine testing in both clinical and laboratory practice.

Detection of antigen in the coelomocytes of the earthworm, Eisenia foetida (Annelida).

Earthworms, Eisenia foetida, are able to respond to antigenic stimulation by the formation of the antigen-binding molecules by coelomocytes--the effector cells of annelids' defence reactions. The ability to react with gold-labelled antigen was detected in agranular coelomocytes by electron microscopy. Furthermore, flow cytometry analysis used for quantitative evaluation of antigen binding showed significant increase of both antigen-binding cells and the amount of antigen bound per cell after stimulation. The antigen binding was inhibited by preincubation of cells with several similar proteins, although the most potent inhibitor was the immunizing antigen.

Limitations of transmembrane transport in drug delivery.

The plasma membrane of all living cells controls the flow of substances, energy as well as information, between the internal cell order and surrounding cell disorder. There are three general routes along which substances may cross this barrier; free diffusion, passive and active transport, and endocytic processes. The subject of polymer drugs where biologically inert polymers bear therapeutically active low molecular weight drugs and targeting moiety became a popular issue in last decade. This review is devoted to the question of the interaction of drugs with the plasma membrane and their transport across it. As the polymer-drug conjugates are macromolecular substances, the main emphasis is focused on the problems of phagocytosis and pinocytosis.

The transmembrane and intracellular transport of drugs: interactions with the cytoskeletal network.

The transport of molecules and/or larger corpuscular material into the cells takes place in plasma membrane and plasma membrane-derived vesicles and vacuoles. Transmembrane and intracellular transport of various materials plays an essential role in the final cellular effects of the drugs. Cytoskeletal network forms a three-dimensional array in the cytoplasm of cells and is closely related to the plasma membrane. Thus, the cytoskeleton significantly affects various processes such as endocytosis, organization and fluidity of the membrane, activity of ion channels, or localization of intracellular organelles. The interactions of the cytoskeletal system with cellular transport of drugs are the scope of this article.