Statin treatment reduces matrix degradation capacity of proinflammatory polarized macrophages.

BACKGROUND AND AIMS: Macrophages are versatile immune cells involved in tissue degradation and remodeling. Proinflammatory macrophages have the highest capacity of matrix degradation and proteolysis. Within atherosclerotic lesions, proinflammatory macrophages are associated with unstable plaques. Statins have been demonstrated to increase plaque stability. Possible changes of polarized macrophage tissue degradation behavior under statin treatment are currently unknown. METHODS: Polarized macrophages were tested in vitro for matrix degradation capacity with or without statin treatment. RESULTS: Proinflammatory macrophages show high matrix degradation capacity, which is lost after statin treatment. Statin concentrations were within a physiological range and did not influence overall macrophage polarization. Proinflammatory macrophages showed however a loss of filopodia where activators of MMPs are located. Loss of matrix degradation in proinflammatory macrophages was associated with changes of MMP14 activation and loss of uPAR localization at filopodia. Supplementation of mevalonate restored localization of uPAR to cellular protrusions and matrix degradation capacity. CONCLUSION: Statins reduce the matrix degradation potential of proinflammatory macrophages by reducing uPAR localization to cellular filopodia and reducing intracellular MMP14 activation.

Effect of intravenous immunoglobulin administration on erythrocyte and leucocyte parameters.

BACKGROUND: Intravenous immunoglobulins (IVIG) are an attractive therapeutic tool for therapy of toxic epidermal necrolysis and severe forms of certain autoimmune diseases, including dermatomyositis, autoimmune blistering diseases, systemic vasculitis and lupus erythematodes. OBJECTIVES: Prompted by a case of IVIG-associated haemolytic anaemia, the effects of IVIG administrations on haematological parameters in patients with dermatological conditions were investigated. METHODS: Erythrocyte and leucocyte parameters were retrospectively analysed in 16 patients who had received IVIG at doses from 1 to 3 g/kg bodyweight (n = 35 cycles). The influence of IVIG on leucocyte survival was determined in vitro. RESULTS: Decreased absolute erythrocyte numbers, haemoglobin and haematocrit levels and a case of haemolytic anaemia were linked to transfusion of high-, but not low-dose IVIG. In contrast, leucopenia post-IVIG occurred in the vast majority of the recipients, unrelated to the administered IVIG amounts. In vitro investigations revealed a dose-dependent impairment of cell survival by IVIG in the neutrophil and monocyte, but not in the lymphocyte subpopulations. In several IVIG preparations, substantial amounts of blood group anti-A/anti-B antibodies were detected which could have accounted for the observed changes in the haematological parameters in our study cohort. CONCLUSIONS: IVIG products should be administered strictly according to indications. Commercially available IVIG products can contain blood group-specific antibodies that may induce haemolysis in some recipients. Monitoring of blood counts during applied IVIG therapy, especially when high doses are administered, is recommended.

Difference in release kinetics of unwashed and washed platelet-released supernatants from bone substitute materials: the impact of platelet preparation modalities.

BACKGROUND AND OBJECTIVE: In regenerative dentistry, platelet preparations are applied to stimulate bone healing and periodontal regeneration. Here, we pursue a strategy where bone substitutes are used as carriers for platelet-released supernatants. The mitogenic capacity and release kinetics of loaded bone substitutes were assessed. MATERIAL AND METHODS: Platelet-released supernatants of washed platelets (washed PRS) and platelet-released supernatants of unwashed platelets (unwashed PRS) were lyophilized onto the bone substitutes deproteinized bovine bone mineral, hydroxyapatite and ß-tricalcium phosphate. Scanning electron microscopy images were taken. Supernatants of bone substitutes were collected at hours 1, 3, 6, 24, and 48 and medium was replaced. We evaluated the protein content with the bicinchoninic acid assay and the effect on proliferation using bioassays with human periodontal fibroblasts. Release of growth factors from the loaded bone substitutes was measured based on the platelet-derived growth factor isoform (PDGF-BB) and thrombin immunoassays. Furthermore, we assessed DNA and RNA content of washed PRS and unwashed PRS. RESULTS: Unwashed PRS showed higher total protein concentrations than washed PRS, while the concentration of PDGF-BB, thrombin, DNA, RNA and their mitogenic effect was not significantly different. The bone substitute materials adsorbed protein over time but no significant changes in overall appearance was found. Supernatants collected from unwashed PRS-loaded bone substitute after 1 h induced a potent mitogenic response in periodontal fibroblasts. This pro-mitogenic capacity of the supernatants decreased over the observation period. Supernatants of washed PRS-loaded bone substitutes did not induce a substantial mitogenic effect. Levels of PDGF-BB, thrombin and protein were higher in supernatants of unwashed PRS-loaded bone substitutes than of washed PRS-loaded bone substitutes. CONCLUSION: Bone substitutes loaded with unwashed PRS, but not bone substitutes loaded with washed PRS show continuously declining release kinetics. These data suggest that plasma components in platelet preparations can modify the release kinetics profile.

Platelet-borne complement proteins and their role in platelet-bacteria interactions.

Essentials Platelets play an important role in pathogen recognition. Platelets contain several complement factors and can interact with E. coli. Platelet's complement protein C3 differs from plasmatic C3 in its electrophoretic mobility. Upon contact with bacteria, platelets are activated and can enhance complement activation. SUMMARY: Background The role of platelets in immune defense is increasingly being recognized. Platelets bind complement proteins from plasma, initiate complement activation, and interact with bacteria. However, the contribution of platelets to complement-mediated defense against bacterial infections is not known in detail. Objectives To assess platelet interactions with Escherichia coli strains, and evaluate the contributions of platelet complement proteins to host defense. Methods We studied the cell-cell interactions of a pathogenic and a non-pathogenic E. coli strain with platelet concentrates, washed platelets and manually isolated platelets by flow cytometry and ELISA. The presence of complement proteins and complement RNA in megakaryocytes and platelets was analyzed by PCR, RT-PCR, confocal microscopy, and western blotting. Results Incubation with E. coli leads to platelet activation, as indicated by the expression of CD62P and CD63 on the platelet surface. RNA and protein analyses show that megakaryocytes and platelets contain complement C3, and that platelet C3 migrates differently on polyacrylamide gels than plasmatic C3. Activation of platelets by bacteria leads to translocation of C3 to the cell surface. This translocation is not induced by thrombin receptor activating peptide or lipopolysaccharide. Interaction of platelets with E. coli occurs even in the absence of plasma proteins, and is independent of platelet toll-like receptor 4 and α2b ß3 (glycoprotein IIbIIIa). Conclusion Platelets contain a specific form of C3. Importantly, they can modulate immune defense against bacteria by enhancing plasmatic complement activation.

Beta2-adrenergic receptor agonists reduce proliferation but not protein synthesis of periodontal fibroblasts stimulated with platelet-derived growth factor-BB.

OBJECTIVE: Catecholamines released from ß-adrenergic neurons upon stress can interfere with periodontal regeneration. The cellular mechanisms, however, are unclear. Here, we assessed the effect of catecholamines on proliferation of periodontal fibroblasts. METHODS: Fibroblasts from the gingiva and the periodontal ligament were exposed to agonists of the ß-adrenergic receptors; isoproterenol (ISO, non-selective ß-adrenergic agonist), salbutamol (SAL, selective ß2-adrenergic receptor agonist) and BRL 37344 (BRL selective ß3-receptor agonist). Proliferation was stimulated with platelet-derived growth factor-BB (PDGF-BB). Pharmacological inhibitors and gene expression analysis further revealed ß-adrenergic signalling. RESULTS: Gingiva and periodontal ligament fibroblast express the ß2-adrenergic receptor. ISO and SAL but not BRL decreased proliferation of fibroblasts in the presence of PDGF-BB. The inhibitory effect of ß-adrenergic signalling on proliferation but not protein synthesis in response to PDGF-BB was reduced by propranolol, a non-selective ß-adrenergic antagonist. CONCLUSIONS: These results suggest that ß2-receptor agonists can reduce the mitogenic response of periodontal fibroblasts. These data add to the compelling concept that blocking of ß2-receptor signalling can support tissue maintenance and regeneration.

Red blood units collected from bone marrow harvests after mononuclear cell selection qualify for autologous use.

BACKGROUND: After large volume bone marrow (BM) harvest, donors and patients can develop severe anaemia, because collected BM can contain up to 20% of their red cell mass. In a prospective analysis, we investigated the feasibility to recover red blood cells (RBCs) from the harvested BM and investigated whether these RBC units meet the quality requirements of the European Council. PATIENTS AND METHODS: From 19 patients (median age 51 yrs, range 31-77) with acute myocardial infarction, who participated in the MYSTAR study, a median volume of 1299 ml (range, 700-1870 ml) BM was collected. During BM processing, mononuclear cells (MNC) were separated using the Cobe Spectra apheresis system and the residual RBCs were collected in a separate bag. The quality of the collected RBCs was assessed by measuring LDH, free haemoglobin, potassium and lactate. Haemolysis was calculated and the intracellular concentration of ATP, ADP, AMP was determined by HPLC. RESULTS: RBC units recovered from BM after MNC separation had a mean volume of 312 +/- 95 ml with a haematocrit of 47 +/- 8.9%, a haemoglobin content of 51 +/- 15 g per unit, a haemolysis of 0.15 +/- 0.005%, a pH of 6.8 +/- 0.007 and an intracellular ATP concentration of 135 pmol/10(6) RBC +/- 41, which is comparable with freshly collected packed red blood cells (PRBCs). CONCLUSION: RBCs, collected from bone marrow harvests, can be used for autologous blood support to minimize allogeneic blood transfusions in donors and patients after large volume BM donation.

Shift of C3 deposition from localization in the glomerulus into the tubulo-interstitial compartment in the absence of secreted IgM in immune complex glomerulonephritis.

The role of secretory IgM in protecting kidney tissue from immune complex glomerulonephritis induced by 4 mg horse spleen apoferritin and 0.05 mg lipopolysaccharide has been investigated in mutant mice in which B cells do not secrete IgM, but are capable of expressing surface IgM and IgD and secreting other Ig isotypes. Glomerular size, number of glomeruli per cross-section, glomerular cellularity and urine content of protein and creatinine was comparable in treated secreted IgM (sIgM)-deficient and wild-type mice. Assessment of urinary proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed a 30 kDa low molecular weight protein in treated sIgM-deficient animals only, reflecting dysfunction of proximal tubules. A shift of bound C3 from glomeruli to the tubulo-interstitial compartment in sIgM-deficient mice also suggests tubulo-interstitial damage. In contrast, local C3 synthesis within the kidney tissue did not differ between the two treated groups. Apoptosis physiologically present to maintain kidney cell homeostasis was increased slightly in treated wild-type mice. These results indicate that secretory IgM can protect the tubulo-interstitial compartment from immune complex-induced damage without having an effect on the glomerulus.

Apheresis products of the Amicus and the AS.TEC 204 cell separators are comparable with regard to dendritic cells derived from the mononuclear cell collection.

BACKGROUND: In this study, we investigated the quality of autologous mononuclear cells (MNC) collected with two different cell separators using standard MNC-apheresis procedure modalities. MNCs were purified by density gradient centrifugation and cultured according to standard protocols to generate dendritic cells (DC) and 1 x 10(7)/ml immature DCs were pulsed with tumour lysate for 3 days and subsequently characterized by fluorescent-activated cell sorter analysis. RESULTS: No difference was found in the monocyte content of either apheresis product (P = 0.07) and in the overall yield of MNCs (P = 0.7). Mature DCs as defined by their phenotype revealed also no significant difference: Amicus, 118 x 10(6) cells +/- 91 vs. AS.TEC 204, 128 x 10(6) cells +/- 137 (P = 0.55), respectively, although the contamination with platelets (threefold) and red cells (twofold) was significantly higher in the AS.TEC 204 group (P < 0.05) than in the Amicus group. CONCLUSION: The Amicus and the AS.TEC 204 are equally capable in providing MNCs for the generation of DCs and the amount of concomitantly collected red cells and platelets had no impact on the final DC yield.

STRO-1+ mesenchymal precursor cells located in synovial surface projections of patients with osteoarthritis.

OBJECTIVE: To investigate the presence of mesenchymal precursor cells (MPCs) in synovial surface projections of patients with osteoarthritis (OA), to characterize their phenotype and to show their localization. METHODS: Progenitor cells in synovial surface projections were identified by immunohistochemistry, morphometric analysis and confocal laser scanning microscopy using the following phenotypic markers: STRO-1, CD34, and alpha smooth muscle actin (alpha-SMA). RESULTS: In the synovial tissue of all 21 patients with OA MPCs were detected. Immunohistochemistry and subsequent morphometric analysis showed that approximately twice as many STRO-1+ cells/mm2 were observed in synovial tissue of patients with OA as compared to healthy organ donors and that number of STRO-1+ cells/mm2 correlated with total cell number/mm2. Interestingly, in the synovial tissue of patients with OA, twice as many STRO-1+ cells/mm2 were found in synovial surface projections as compared to the sublining area without villi. Using confocal laser scanning microscopy two populations of STRO-1+ MPCs could be detected in synovial surface projections. Single STRO-1+ cells that co-expressed alpha-SMA resemble a population of pericyte precursors required to stabilize the immature vasculature. The second STRO-1+ cell population that was found lacked alpha-SMA but co-expressed CD34 on their surface with low intensity. CONCLUSION: Here we can show that in the synovial tissue of patients with OA twice as many STRO-1+ MPCs can be found in synovial surface projections as compared to the sublining area. These cells are preferentially located at the basis and in the protruding end of the synovial surface projection.

Proliferation of dental pulp fibroblasts in response to thrombin involves mitogen-activated protein kinase signalling.

AIM: To examine the involvement of mitogen-activated protein kinases (MAPK) signalling on thrombin-stimulated human dental pulp fibroblasts (DPF). METHODOLOGY: Dental pulp fibroblasts were isolated from dental pulp connective tissue of third molars and expanded in vitro. Expression of thrombin receptors was analysed by RT-PCR, and cell proliferation was measured by 3[H]-thymidine incorporation assay. Phosphorylation levels of MAPK were determined by Western blot analysis, and alkaline phosphatase activity was measured to serve as a marker for odontogenic differentiation. Statistical analysis was performed by Student's t-test. RESULTS: Dental pulp fibroblasts express the thrombin receptors protease-activated receptor-1 (PAR-1), PAR-3 and PAR-4. Measurement of 3[H]-thymidine incorporation revealed a dose-dependent increase of DNA synthesis in response to thrombin treatment. The thrombin-induced mitogenic activity was decreased by the extracellular signal-regulated protein kinase (ERK) signalling inhibitor PD98059 (P < 0.05), and by SB203580 (P < 0.05), a p38 MAPK inhibitor. Western blot analysis demonstrated increased phosphorylation of ERK in DPF following stimulation with thrombin, while p38 MAPK and c-Jun NH2-terminal kinase (JNK) were not activated. Alkaline phosphatase activity of DPF remained unchanged upon incubation with thrombin. CONCLUSIONS: These results suggest that signalling via MAPK mediates the mitogenic activity of thrombin on DPF and may thus play a role during the early stages of pulp repair.

Quality of packed red blood cells and platelet concentrates collected by multicomponent collection using the MCS plus device.

The demand for blood components is constantly increasing, while the exclusion criteria for donors are strengthened in order to reach maximal safety for donors and patients. To counterbalance reduced availability of volunteers, multicomponent collections (MCC) is an attractive approach to produce more than one component during a single apheresis procedure from one donor, such as packed red blood cells (PRBCs) and platelet concentrates (PCs). Further, the exposures of patients to a limited number of donors reduces the possibility of alloimmunization and transfusion-related diseases. We measured the quality of PRBCs and PCs obtained by MCC, using the MCS+ device with the LDPRBC program, Revision B, and compared them with the quality of manually collected PRBCs and PCs collected with the Revision C2 of the MCS+. We found higher pH levels and lower hemolysis assessed by means of fHb and K+ in the supernatant of PRBCs over the whole storage period of 42 days in MCC-derived PRBCs. The functional metabolism assessed by intracellular ATP was higher in PRBCs collected by MCC than in manually collected units. Furthermore, PCs obtained during MCC showed an increase in p-selectin expression on day 5 of storage compared to PCs collected with the Revision C2 of the MCS+. The p-selectin expression on MCC platelets was within the range of p-selectin expression found in PCs obtained by other apheresis devices. These results indicate less storage lesion in MCC-derived PRBCs compared to manually collected units and no compromise in the quality of MCC PCs obtained in the same apheresis procedure.

Platelet-released supernatants stimulate formation of osteoclast-like cells through a prostaglandin/RANKL-dependent mechanism.

Platelets are activated at fracture sites or upon the insertion of implants as a consequence of vascular disruption and secrete the contents of their granules into the developing hematoma. The regeneration of injured tissue requires bone remodeling and the resorbing activity of osteoclasts. To test our hypothesis that platelets can stimulate osteoclastogenesis, we examined the effects of supernatants released from thrombin-activated platelets on osteoclast-like cell formation in murine bone marrow cultures. Histochemical analysis indicated the presence of bone-resorbing, tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. Transcripts that are characteristically expressed in native osteoclasts were increased in these cultures, as determined by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. The inhibition of both cyclooxygenases with indomethacin, as well as the addition of the cyclooxygenase-2 (COX-2)-selective antagonist, NS398, completely blocked osteoclast-like cell formation and decreased endogenous prostaglandin E(2) production. Platelet-released supernatants stimulated the expression of receptor activator of NF-kappaB ligand (RANKL), whereas mRNA levels of osteoprotegerin (OPG) were decreased. The formation of osteoclast-like cells was prevented by recombinant OPG. Our results suggest that COX-2 activity is necessary for osteoclast-like cell formation in response to platelet-released supernatants, and that endogenously produced prostaglandin E(2) can, in turn, increase the RANKL:OPG ratio, indicating that platelets can contribute to bone remodeling by stimulation of osteoclastogenesis.

Increased expression of the blood group-related Lewis Y antigen on synovial fluid granulocytes of patients with arthritic joint diseases.

OBJECTIVE: To evaluate the expression of the carbohydrate structures Lewis Y (LeY), sialyl-LeX (sLeX) and Lewis X (LeX) on paired peripheral blood (PB) and synovial fluid (SF) granulocytes in patients with arthritic diseases. METHODS: Ten patients with rheumatoid arthritis (RA), seven patients with spondyloarthritis (SA) and eight patients with osteoarthritis (OA) were studied. Granulocyte expression of the Le oligosaccharides was analysed by fluorescence-activated cell sorting. RESULTS: SF granulocytes of patients with RA, SA and OA expressed higher levels of the LeY oligosaccharide than PB granulocytes. Increases in LeY on SF granulocytes were similar in all three underlying diseases. No differences in the expression of the Le antigens were detected between PB granulocytes of patients and healthy individuals. Expression of sLeX and LeX showed no variation between SF and PB neutrophils. CONCLUSION: The selective increase in LeY antigen on SF granulocytes in RA, SA and OA suggests a role of the LeY oligosaccharide in granulocyte traffic and inflammatory responses.

Altered intracellular purine nucleotides in gamma-irradiated red blood cell concentrates.

BACKGROUND AND OBJECTIVES: Gamma irradiation at a dose of 30 Gy induces deterioration of erythrocytes, resulting in storage lesions that significantly shorten the shelf-life of packed red cell concentrates (RCCs). The aim of the present study was to investigate the effect of gamma irradiation on intracellular purine nucleotides of red blood cells during storage. MATERIALS AND METHODS: Three-day-old leucocyte-depleted saline-adenine-glucose-mannitol (SAGM)-preserved RCCs, obtained from the Blood Service of the Austrian Red Cross, were gamma irradiated with 30 Gy. Samples were taken on days 1, 2, 3 and 7 after irradiation and subsequently at weekly intervals up to the end the of shelf-life (day 39 after irradiation) and were investigated for the K+ and Na+ content in the supernatant, for intracellular concentrations of ATP, ADP, ITP, IDP, GTP and GDP of erythrocytes, and for haemolysis. RESULTS: Within the first 24 h after gamma irradiation, no metabolic or biochemical changes were detectable in the RCCs. The K+ concentration in the supernatant increased after 24 h, while the Na+ concentration decreased in irradiated units and this ion disequilibrium persisted until the end of the shelf-life. After an initial increase of intracellular ATP, ADP and GTP during the first week of storage, the intracellular concentrations of ATP, ADP, GTP and ITP decreased, while IDP increased. The decrease of ATP and ADP was found to be more pronounced in irradiated units. At the end of the shelf-life, the ATP, GTP and ITP concentrations of irradiated RCCs had decreased to < 10% of the initial level and the critical threshold of 0.8% haemolysis was reached. CONCLUSION: Gamma irradiation of SAGM-preserved RCCs leads to serious deterioration of the purine nucleotide metabolism of erythrocytes during storage, which can reduce the in vivo recovery of the transfused red cells.

Increased serum flt3-ligand in healthy donors undergoing granulocyte colony-stimulating factor-induced peripheral stem cell mobilization.

The effect of granulocyte colony-stimulating factor (G-CSF) induced mobilization of peripheral blood progenitor cells (PBPC) on the endogenous serum levels of cytokines stem cell factor (SCF) and flt3-ligand (flt3-L) was studied in 18 healthy subjects undergoing allogeneic PBPC donation. Donors received a standardized mobilization regime consisting of a 4-day course of G-CSF, with leukapheresis on day 5. Endogenous serum flt3-L and SCF were determined prior to G-CSF administration, on the day of leukapheresis, and followed up until day +100 after cessation of G-CSF administration. The administration of G-CSF resulted in a transient elevation of endogenous flt3-L serum levels. At the day of leukapheresis serum flt3-L showed a median increase of 75% compared to serum flt3-L levels obtained before G-CSF treatment. The increase in serum flt3-L levels showed no correlation with the total number of progenitor cells mobilized. Cessation of G-CSF treatment led to normalization of serum flt3-L within 7 days post G-CSF administration. In contrast, serum CSF levels remained unchanged in response to G-CSF administration. Our results demonstrate a transient surge in serum flt3-L in relation to G-CSF-induced PBPC mobilization, although the assessment of endogenous flt3-L give no information regarding the ability for G-CSF-induced PBPC recruitment in healthy individuals.

Binding of disease-associated prion protein to plasminogen.

Transmissible spongiform encephalopathies are associated with accumulation of PrP(Sc), a conformer of a cellular protein called PrP(C). PrP(Sc) is thought to replicate by imparting its conformation onto PrP(C) (ref. 1), yet conformational discrimination between PrP(C) and PrP(Sc) has remained elusive. Because deposition of PrP(Sc) alone is not enough to cause neuropathology, PrP(Sc) probably damages the brain by interacting with other cellular constituents. Here we find activities in human and mouse blood which bind PrP(Sc) and prion infectivity, but not PrP(C). We identify plasminogen, a pro-protease implicated in neuronal excitotoxicity, as a PrP(Sc)-binding protein. Binding is abolished if the conformation of PrP(Sc) is disrupted by 6M urea or guanidine. The isolated lysine binding site 1 of plasminogen (kringles I-III) retains this binding activity, and binding can be competed for with lysine. Therefore, plasminogen represents the first endogenous factor discriminating between normal and pathological prion protein. This unexpected property may be exploited for diagnostic purposes.

Concurrence of sarcoidosis and aortitis: case report and review of the literature.

Takayasu arteritis (TA) is a rare manifestation of systemic large vessel vasculitis which affects predominantly the aorta and its main branches, but often remains unrecognised owing to delayed diagnosis and non-characteristic clinical features. Sarcoidosis, too, is a systemic inflammatory disease which can affect virtually any organ system. Reports about the coincidence of both diseases have appeared. The case presented here is characterised by a significant time lag between detection of TA and appearance of clinical signs of sarcoidosis. The woman, now 39 years old, had erythema nodosum, circumscript alopecia, and recurrent uveitis, which dated back to 1980 and was attributed to sarcoidosis. At least 12 years later aortic valve insufficiency with progressive cardiac failure developed. Histology performed at the time of aortic valve prosthesis in 1997 disclosed a diagnosis of TA, which was confined to the aortic root. Incidentally, sarcoidosis was diagnosed in adjacent lymph nodes. A thorough check up failed to detect further manifestations of TA; thus, possibly, the patients had aortitis similar to, but not identical with, TA. Several related cases previously reported are discussed, suggesting that both diseases may be inherently related as they are characterised by certain non-specific, immunoinflammatory abnormalities. This case report suggests that the prevalence of TA, or related forms of arteritis, may be higher than expected and should be considered, especially in younger patients with non-characteristic cardiovascular symptoms and suspected systemic inflammatory disease. Moreover, the association with sarcoidosis in this and other previously described cases suggests that the two diseases may be related and that TA or TA-like vasculitis may even be a complication of sarcoidosis.

Humoral response to herpes simplex virus is complement-dependent.

The complement system represents a cascade of serum proteins, which provide a major effector function in innate immunity. Recent studies have revealed that complement links innate and adaptive immunity via complement receptors CD21/CD35 in that it enhances the B cell memory response to noninfectious protein antigens introduced i.v. To examine the importance of complement for immune responses to virus infection in a peripheral tissue, we compared the B cell memory response of mice deficient in complement C3, C4, or CD21/CD35 with wild-type controls. We found that the deficient mice failed to generate a normal memory response, which is characterized by a reduction in IgG antibody and germinal centers. Thus, complement is important not only in the effector function of innate immunity but also in the stimulation of memory B cell responses to viral-infected cell antigens in both blood and peripheral tissues.