Platelet-rich fibrin (PRF) is an autologous fibrin sealant (FS) enriched with a platelet concentrate (> 1,000,000 platelets/microL) produced by the automated Vivostat system and used to enhance wound healing. The effects of PRF were compared with supernatant from thrombin-activated platelet concentrate, recombinant human platelet-derived growth factor (rhPDGF) isoforms, and a homologous FS in cultured normal human dermal fibroblasts. Also, the release of selected endogenous growth factors from PRF and their stability against proteolytic degradation were studied. The proliferative effect of PRF exceeded that of FS and rhPDGF-BB, although it was lower than thrombin-activated platelet concentrate possibly due to sustained growth factor release from platelets in PRF. Anti-PDGF antibody blocked the mitogenic effect of rhPDGF-BB but not that of PRF in growth-arrested fibroblasts. PRF promoted secretion of carboxyterminal propeptide of type I collagen into conditioned medium while rhPDGF-AB had no significant effect on collagen biosynthesis. Limited proteolysis of PDGF-AB and no proteolysis of transforming growth factor-beta1 (TGF-beta1) in PRF were observed with trypsin treatment, whereas rhPDGF-AB and rhTGF-beta1 in bovine serum albumin, matching the total protein concentration of PRF, were almost completely degraded after 24 hours at 37 degrees C. To conclude, PRF provides sustained release and protection against proteolytic degradation of endogenous fibrogenic factors important for wound healing.

Clinical experiments have shown that the Ab-dependent cell-mediated inhibition of Plasmodium falciparum is a major mechanism controlling malaria parasitemia and thereby symptoms. In this study, we demonstrate that a single merozoite per monocyte (MN) is sufficient to trigger optimal antiparasitic activity. Using particulate Ag as pseudomerozoites, we show that only Ags, and no other parasite-derived factor, are required to trigger MN activation and that a single Ag is as potent as the complex combination of Ags constituting the merozoite surface. Moreover, we found that soluble Ags binding at least two Abs are as effective as the parasite at stimulating MN and that nonmalarial Ags are as efficient provided they are targeted by cytophilic Abs. Indeed, only cytophilic IgGs are potent and, in agreement with immunoepidemiological findings, IgG3 is superior to IgG1. Very low Ab concentrations (>700 pM), i.e., in the range of molecules having a hormonal effect, are effective, in contrast to Abs having a direct, neutralizing effect. Finally, Ab-dependent cell-mediated inhibition proved to require the synergistic activation of both FcγRIIa and FcγRIIIa which both distinguish it from other Ab-dependent cellular cytotoxicity and implies that all MN are not equally effective. These findings have both fundamental and practical implications, particularly for vaccine discovery.

Immunoglobulins from individuals with immunity to malaria have a strong antiparasitic effect when transferred to Plasmodium falciparum malaria infected patients. One prominent target of antiparasitic antibodies is the merozoite surface antigen 3 (MSP-3). We have investigated the antibody response against MSP-3 residues 194 to 257 (MSP-3 194-257 ) on the molecular level. mRNA from peripheral blood leukocytes from clinically immune individuals was used as a source of Fab (fragment antibody) genes. A Fab-phage display library was made, and three distinct antibodies designated RAM1, RAM2, and RAM3 were isolated by panning. Immunoglobulin G1 (IgG1) and IgG3 full-length antibodies have been produced in CHO cells. Reactivity with the native parasite protein was demonstrated by immunofluorescence microscopy, flow cytometry, and immunoblotting. Furthermore, the antiparasitic effect of RAM1 has been tested in vitro in an antibody-dependent cellular inhibition (ADCI) assay. Both the IgG1 and the IgG3 versions of the antibody show an inhibitory effect on parasite growth.Clinical immunity to Plasmodium falciparum malaria is gradually acquired over a dozen years of intense exposure to the parasite (12). Acquired immunity to malaria has been termed premunition and is characterized as being nonsterile and incomplete (43). The exact mechanism responsible for premunition is not known with certainty. However, a number of clinical studies carried out in the early sixties (9, 16, 23)-and subsequently confirmed and extended in the nineties (2, 33)-showed an unambiguous antiparasitic effect of antibodies transferred from adults with immunity to malaria to malariainfected infants. Clinical effects observed in one of these studies correlated with the effect measured in the in vitro assay termed antibody-dependent cellular inhibition (ADCI) (2, 4). In the ADCI assay, immune antibody cooperates with monocytes in an in vitro malaria culture, and the antiparasitic effect is demonstrated by parasite growth inhibition. It has been shown that the antibody-merozoite complex by a contact-dependent mechanism stimulates the monocyte to secrete substances toxic to the asexual blood stages. The specific substances responsible for the subsequent, non-contact-dependent parasite growth inhibition include tumor necrosis factor alpha together with other molecules that are yet to be identified (4). The ADCI assay has been used for identification and characterization of the merozoite surface protein 3 (MSP-3) (27).An invariable structural feature of all reported MSP-3 sequences is the presence of three regions each of which contains three, four, or five conserved heptad repeat units. Previously published structural analyses suggest that the heptad repeat regions have an amphipathic alpha-helical secondary structure. A coiled-coil bundle conformation including these regions is a theoretical possibility supported by experimental data (24). The C-terminal part of MSP-3 contains a leucine zipper-like domain possibly implicated in dimerization and the formation...

Our set-up was very reliable for determination of fetal RhD genotype, and thus will be of value in prenatal Rh prophylaxis and in the management of immunized women.

The molecular anomalies in chronic wounds are more subtle than the current paradigm and neither excessive proteinase activity nor deficiencies of examined extracellular matrix proteins, growth factors or angiogenic/angiostatic factors appear to contribute significantly to the nonhealing state of venous leg ulcers.