Lack of Serologic Evidence of Infection Among Health Care Personnel and Other Contacts of First 2 Confirmed Patients With COVID-19 in Illinois, 2020

OBJECTIVES

Widespread global transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), continues. Many questions remain about asymptomatic or atypical infections and transmission dynamics. We used comprehensive contact tracing of the first 2 confirmed patients in Illinois with COVID-19 and serologic SARS-CoV-2 antibody testing to determine whether contacts had evidence of undetected COVID-19.

METHODS

Contacts were eligible for serologic follow-up if previously tested for COVID-19 during an initial investigation or had greater-risk exposures. Contacts completed a standardized questionnaire during the initial investigation. We classified exposure risk as high, medium, or low based on interactions with 2 index patients and use of personal protective equipment (PPE). Serologic testing used a SARS-CoV-2 spike enzyme-linked immunosorbent assay on serum specimens collected from participants approximately 6 weeks after initial exposure to either index patient. The 2 index patients provided serum specimens throughout their illness. We collected data on demographic, exposure, and epidemiologic characteristics.

RESULTS

Of 347 contacts, 110 were eligible for serologic follow-up; 59 (17% of all contacts) enrolled. Of these, 53 (90%) were health care personnel and 6 (10%) were community contacts. Seventeen (29%) reported high-risk exposures, 15 (25%) medium-risk, and 27 (46%) low-risk. No participant had evidence of SARS-CoV-2 antibodies. The 2 index patients had antibodies detected at dilutions >1:6400 within 4 weeks after symptom onset.

CONCLUSIONS

In serologic follow-up of the first 2 known patients in Illinois with COVID-19, we found no secondary transmission among tested contacts. Lack of seroconversion among these contacts adds to our understanding of conditions (ie, use of PPE) under which SARS-CoV-2 infections might not result in transmission and demonstrates that SARS-CoV-2 antibody testing is a useful tool to verify epidemiologic findings.

Inappropriate Administration of Rabies Postexposure Prophylaxis, Cook County, Illinois, USA

Administration of rabies postexposure prophylaxis (PEP) is expensive and time-consuming. In suburban Cook County, Illinois, USA, administration of 55.5% of PEP treatments did not follow Advisory Committee on Immunization Practices guidelines. Health department consultation lowered the odds of inappropriate PEP administration by 87%. Providers should consult their health department before prescribing PEP.

Enhanced contact investigations for nine early travel-related cases of SARS-CoV-2 in the United States

Coronavirus disease 2019 (COVID-19), the respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified in Wuhan, China and has since become pandemic. In response to the first cases identified in the United States, close contacts of confirmed COVID-19 cases were investigated to enable early identification and isolation of additional cases and to learn more about risk factors for transmission. Close contacts of nine early travel-related cases in the United States were identified and monitored daily for development of symptoms (active monitoring). Selected close contacts (including those with exposures categorized as higher risk) were targeted for collection of additional exposure information and respiratory samples. Respiratory samples were tested for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction at the Centers for Disease Control and Prevention. Four hundred four close contacts were actively monitored in the jurisdictions that managed the travel-related cases. Three hundred thirty-eight of the 404 close contacts provided at least basic exposure information, of whom 159 close contacts had ≥1 set of respiratory samples collected and tested. Across all actively monitored close contacts, two additional symptomatic COVID-19 cases (i.e., secondary cases) were identified; both secondary cases were in spouses of travel-associated case patients. When considering only household members, all of whom had ≥1 respiratory sample tested for SARS-CoV-2, the secondary attack rate (i.e., the number of secondary cases as a proportion of total close contacts) was 13% (95% CI: 4-38%). The results from these contact tracing investigations suggest that household members, especially significant others, of COVID-19 cases are at highest risk of becoming infected. The importance of personal protective equipment for healthcare workers is also underlined. Isolation of persons with COVID-19, in combination with quarantine of exposed close contacts and practice of everyday preventive behaviors, is important to mitigate spread of COVID-19.

Enhanced contact investigations for nine early travel-related cases of SARS-CoV-2 in the United States

Coronavirus disease 2019 (COVID-19), the respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first identified in Wuhan, China and has since become pandemic. In response to the first cases identified in the United States, close contacts of confirmed COVID-19 cases were investigated to enable early identification and isolation of additional cases and to learn more about risk factors for transmission. Close contacts of nine early travel-related cases in the United States were identified and monitored daily for development of symptoms (active monitoring). Selected close contacts (including those with exposures categorized as higher risk) were targeted for collection of additional exposure information and respiratory samples. Respiratory samples were tested for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction at the Centers for Disease Control and Prevention. Four hundred four close contacts were actively monitored in the jurisdictions that managed the travel-related cases. Three hundred thirty-eight of the 404 close contacts provided at least basic exposure information, of whom 159 close contacts had ≥1 set of respiratory samples collected and tested. Across all actively monitored close contacts, two additional symptomatic COVID-19 cases (i.e., secondary cases) were identified; both secondary cases were in spouses of travel-associated case patients. When considering only household members, all of whom had ≥1 respiratory sample tested for SARS-CoV-2, the secondary attack rate (i.e., the number of secondary cases as a proportion of total close contacts) was 13% (95% CI: 4-38%). The results from these contact tracing investigations suggest that household members, especially significant others, of COVID-19 cases are at highest risk of becoming infected. The importance of personal protective equipment for healthcare workers is also underlined. Isolation of persons with COVID-19, in combination with quarantine of exposed close contacts and practice of everyday preventive behaviors, is important to mitigate spread of COVID-19.

Clinical and virologic characteristics of the first 12 patients with coronavirus disease 2019 (COVID-19) in the United States

Data on the detailed clinical progression of COVID-19 in conjunction with epidemiological and virological characteristics are limited. In this case series, we describe the first 12 US patients confirmed to have COVID-19 from 20 January to 5 February 2020, including 4 patients described previously^1-3. Respiratory, stool, serum and urine specimens were submitted for SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (rRT-PCR) testing, viral culture and whole genome sequencing. Median age was 53 years (range: 21-68); 8 patients were male. Common symptoms at illness onset were cough (n = 8) and fever (n = 7). Patients had mild to moderately severe illness; seven were hospitalized and demonstrated clinical or laboratory signs of worsening during the second week of illness. No patients required mechanical ventilation and all recovered. All had SARS-CoV-2 RNA detected in respiratory specimens, typically for 2-3 weeks after illness onset. Lowest real-time PCR with reverse transcription cycle threshold values in the upper respiratory tract were often detected in the first week and SARS-CoV-2 was cultured from early respiratory specimens. These data provide insight into the natural history of SARS-CoV-2. Although infectiousness is unclear, highest viral RNA levels were identified in the first week of illness. Clinicians should anticipate that some patients may worsen in the second week of illness.

First known person-to-person transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the USA

BACKGROUND

Coronavirus disease 2019 (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first detected in China in December, 2019. In January, 2020, state, local, and federal public health agencies investigated the first case of COVID-19 in Illinois, USA.

METHODS

Patients with confirmed COVID-19 were defined as those with a positive SARS-CoV-2 test. Contacts were people with exposure to a patient with COVID-19 on or after the patient's symptom onset date. Contacts underwent active symptom monitoring for 14 days following their last exposure. Contacts who developed fever, cough, or shortness of breath became persons under investigation and were tested for SARS-CoV-2. A convenience sample of 32 asymptomatic health-care personnel contacts were also tested.

FINDINGS

Patient 1-a woman in her 60s-returned from China in mid-January, 2020. One week later, she was hospitalised with pneumonia and tested positive for SARS-CoV-2. Her husband (Patient 2) did not travel but had frequent close contact with his wife. He was admitted 8 days later and tested positive for SARS-CoV-2. Overall, 372 contacts of both cases were identified; 347 underwent active symptom monitoring, including 152 community contacts and 195 health-care personnel. Of monitored contacts, 43 became persons under investigation, in addition to Patient 2. These 43 persons under investigation and all 32 asymptomatic health-care personnel tested negative for SARS-CoV-2.

INTERPRETATION

Person-to-person transmission of SARS-CoV-2 occurred between two people with prolonged, unprotected exposure while Patient 1 was symptomatic. Despite active symptom monitoring and testing of symptomatic and some asymptomatic contacts, no further transmission was detected.

FUNDING

None.

Complement component 5 does not interfere with physiological hemostasis but is essential for Escherichia coli-induced coagulation accompanied by Toll-like receptor 4

There is a close cross-talk between complement, Toll-like receptors (TLRs) and coagulation. The role of the central complement component 5 (C5) in physiological and pathophysiological hemostasis has not, however, been fully elucidated. This study examined the effects of C5 in normal hemostasis and in Escherichia coli-induced coagulation and tissue factor (TF) up-regulation. Fresh whole blood obtained from six healthy donors and one C5-deficient individual (C5D) was anti-coagulated with the thrombin inhibitor lepirudin. Blood was incubated with or without E. coli in the presence of the C5 inhibitor eculizumab, a blocking anti-CD14 monoclonal antibody (anti-CD14) or the TLR-4 inhibitor eritoran. C5D blood was reconstituted with purified human C5. TF mRNA was measured by quantitative polymerase chain reaction (qPCR) and monocyte TF and CD11b surface expression by flow cytometry. Prothrombin fragment 1+2 (PTF1·2) in plasma and microparticles exposing TF (TF-MP) was measured by enzyme-linked immunosorbent assay (ELISA). Coagulation kinetics were analyzed by rotational thromboelastometry and platelet function by PFA-200. Normal blood with eculizumab as well as C5D blood with or without reconstitution with C5 displayed completely normal biochemical hemostatic patterns. In contrast, E. coli-induced TF mRNA and TF-MP were significantly reduced by C5 inhibition. C5 inhibition combined with anti-CD14 or eritoran completely inhibited the E. coli-induced monocyte TF, TF-MP and plasma PTF1·2. Addition of C5a alone did not induce TF expression on monocytes. In conclusion, C5 showed no impact on physiological hemostasis, but substantially contributed to E. coli-induced procoagulant events, which were abolished by the combined inhibition of C5 and CD14 or TLR-4.

Increased FXYD1 and PGC-1α mRNA after blood flow-restricted running is related to fibre type-specific AMPK signalling and oxidative stress in human muscle

Aim

This study explored the effects of blood flow restriction (BFR) on mRNA responses of PGC‐1α (total, 1α1, and 1α4) and Na⁺,K⁺‐ATPase isoforms (NKA; α_1‐3, β_1‐3, and FXYD1) to an interval running session and determined whether these effects were related to increased oxidative stress, hypoxia, and fibre type‐specific AMPK and CaMKII signalling, in human skeletal muscle.

Methods

In a randomized, crossover fashion, 8 healthy men (26 ± 5 year and 57.4 ± 6.3 mL kg⁻¹ min⁻¹) completed 3 exercise sessions: without (CON) or with blood flow restriction (BFR), or in systemic hypoxia (HYP, ~3250 m). A muscle sample was collected before (Pre) and after exercise (+0 hour, +3 hours) to quantify mRNA, indicators of oxidative stress (HSP27 protein in type I and II fibres, and catalase and HSP70 mRNA), metabolites, and α‐AMPK Thr¹⁷²/α‐AMPK, ACC Ser²²¹/ACC, CaMKII Thr²⁸⁷/CaMKII, and PLBSer¹⁶/PLB ratios in type I and II fibres.

Results

Muscle hypoxia (assessed by near‐infrared spectroscopy) was matched between BFR and HYP, which was higher than CON (~90% vs ~70%; P < .05). The mRNA levels of FXYD1 and PGC‐1α isoforms (1α1 and 1α4) increased in BFR only (P < .05) and were associated with increases in indicators of oxidative stress and type I fibre ACC Ser²²¹/ACC ratio, but dissociated from muscle hypoxia, lactate, and CaMKII signalling.

Conclusion

Blood flow restriction augmented exercise‐induced increases in muscle FXYD1 and PGC‐1α mRNA in men. This effect was related to increased oxidative stress and fibre type‐dependent AMPK signalling, but unrelated to the severity of muscle hypoxia, lactate accumulation, and modulation of fibre type‐specific CaMKII signalling.

Staphylococcus aureus-induced complement activation promotes tissue factor-mediated coagulation

Essentials Complement, Toll-like receptors and coagulation cross-talk in the process of thromboinflammation. This is explored in a unique human whole-blood model of S. aureus bacteremia. Coagulation is here shown as a downstream event of C5a-induced tissue factor (TF) production. Combined inhibition of C5 and CD14 efficiently attenuated TF and coagulation.

SUMMARY

Background There is extensive cross-talk between the complement system, the Toll-like receptors (TLRs), and hemostasis. Consumptive coagulopathy is a hallmark of sepsis, and is often mediated through increased tissue factor (TF) expression. Objectives To study the relative roles of complement, TLRs and TF in Staphylococcus aureus-induced coagulation. Methods Lepirudin-anticoagulated human whole blood was incubated with the three S. aureus strains Cowan, Wood, and Newman. C3 was inhibited with compstatin, C5 with eculizumab, C5a receptor 1 (C5aR1) and activated factor XII with peptide inhibitors, CD14, TLR2 and TF with neutralizing antibodies, and TLR4 with eritoran. Complement activation was measured by ELISA. Coagulation was measured according to prothrombin fragment 1 + 2 (PTF1 + 2 ) determined with ELISA, and TF mRNA, monocyte surface expression and functional activity were measured with quantitative PCR, flow cytometry, and ELISA, respectively. Results All three strains generated substantial and statistically significant amounts of C5a, terminal complement complex, PTF1 + 2 , and TF mRNA, and showed substantial TF surface expression on monocytes and TF functional activity. Inhibition of C5 cleavage most efficiently and significantly inhibited all six markers in strains Cowan and Wood, and five markers in Newman. The effect of complement inhibition was shown to be completely dependent on C5aR1. The C5 blocking effect was equally potentiated when combined with blocking of CD14 or TLR2, but not TLR4. TF blocking significantly reduced PTF1 + 2 levels to baseline levels. Conclusions S. aureus-induced coagulation in human whole blood was mainly attributable to C5a-induced mRNA upregulation, monocyte TF expression, and plasma TF activity, thus underscoring complement as a key player in S. aureus-induced coagulation.

Measles Outbreak in a Child Care Center, Cook County, Illinois, 2015

BACKGROUND

During January-February 2015, Cook County Department of Public Health led an investigation of a measles outbreak predominantly affecting infants at a child care center who were too young for routine immunization with measles-mumps-rubella (MMR) vaccine.

METHODS

Measles cases and contacts were investigated by Illinois public health officials. Cases were isolated for 4 days after rash onset. Exposed healthcare workers and child care center staff were required to provide documentation of receipt of 2 doses of MMR vaccine or laboratory evidence of immunity to return to work. Susceptible contacts were actively monitored for 21 days after exposure and provided postexposure prophylaxis (PEP) if certain criteria were met.

RESULTS

Fifteen confirmed measles cases were identified; 12 (80%) occurred in infants who were attendees of a child care center. Clinical misdiagnosis of 1 case allowed for continued transmission within the center. Twelve (86%) of 14 exposed infants at the child care center were diagnosed with measles; no other attendees or staff were infected. Five cases visited outpatient pediatric clinics during their infectious period, exposing 33 infants. Six exposed child care center staff and 3 healthcare workers did not have documentation of immunity available and were excluded from work until this was obtained. No healthcare-associated transmission was identified. Ninety-one contacts were actively monitored and 20 received PEP.

CONCLUSIONS

This outbreak underscores the vulnerability of infants to measles, the need for early consideration of measles in susceptible patients presenting with a febrile rash illness, and the importance of immunity among individuals working closely with infants.

Using an Emergency Department Syndromic Surveillance System to Evaluate Reporting of Potential Rabies Exposures, Illinois, 2013-2015

OBJECTIVES

Mandatory reporting of potential rabies exposures and initiation of postexposure prophylaxis (PEP) allow local health authorities to monitor PEP administration for errors. Our objectives were to use an emergency department (ED) syndromic surveillance system to (1) estimate reporting compliance for exposure to rabies in suburban Cook County, Illinois, and (2) initiate interventions to improve reporting and reassess compliance.

METHODS

We queried ED records from 45 acute care hospitals in Cook County and surrounding areas from January 1, 2013, through June 30, 2015, for chief complaints or discharge diagnoses pertaining to rabies, PEP, or contact with a wild mammal (eg, bat, raccoon, skunk, fox, or coyote). We matched patients with ≥1 ED visit for potential rabies exposure to people with potential rabies exposure reported to the Cook County Department of Public Health. We considered nonmatches to have unreported exposures. We then initiated active surveillance in July 2015, disseminated education on reporting requirements in August and September 2015, and reassessed reporting completeness from July 2015 through February 2016.

RESULTS

Of 248 patients with rabies-related ED visits from January 2013 through June 2015, 63 (25.4%) were reported. After interventions were implemented to increase reporting compliance, 53 of 98 (54.1%) patients with rabies-related ED visits from July 2015 through February 2016 were reported. Patients with ED visits for potential rabies exposure were twice as likely to be reported postintervention than preintervention (risk ratio = 2.1; 95% CI, 1.6-2.8). The volume of potential rabies exposure cases reported to the health department from July 2015 through February 2016 increased by 252% versus the previous year.

CONCLUSIONS

Potential rabies exposures and PEP initiation are underreported in suburban Cook County. ED syndromic surveillance records can be used to estimate reporting compliance and conduct active surveillance.

Characterization of a hepatitis C virus-like particle vaccine produced in a human hepatocyte-derived cell line

An effective immune response against hepatitis C virus (HCV) requires the early development of multi-specific class 1 CD8+ and class II CD4+ T-cells together with broad neutralizing antibody responses. We have produced mammalian-cell-derived HCV virus-like particles (VLPs) incorporating core, E1 and E2 of HCV genotype 1a to produce such immune responses. Here we describe the biochemical and morphological characterization of the HCV VLPs and study HCV core-specific T-cell responses to the particles. The E1 and E2 glycoproteins in HCV VLPs formed non-covalent heterodimers and together with core protein assembled into VLPs with a buoyant density of 1.22 to 1.28 g cm-3. The HCV VLPs could be immunoprecipited with anti-ApoE and anti-ApoC. On electron microscopy, the VLPs had a heterogeneous morphology and ranged in size from 40 to 80 nm. The HCV VLPs demonstrated dose-dependent binding to murine-derived dendritic cells and the entry of HCV VLPs into Huh7 cells was blocked by anti-CD81 antibody. Vaccination of BALB/c mice with HCV VLPs purified from iodixanol gradients resulted in the production of neutralizing antibody responses while vaccination of humanized MHC class I transgenic mice resulted in the prodution of HCV core-specific CD8+ T-cell responses. Furthermore, IgG purified from the sera of patients chronically infected with HCV genotypes 1a and 3a blocked the binding and entry of the HCV VLPs into Huh7 cells. These results show that our mammalian-cell-derived HCV VLPs induce humoral and HCV-specific CD8+ T-cell responses and will have important implications for the development of a preventative vaccine for HCV.

The key roles of complement and tissue factor in Escherichia coli-induced coagulation in human whole blood

The complement system and the Toll-like (TLR) co-receptor CD14 play important roles in innate immunity and sepsis. Tissue factor (TF) is a key initiating component in intravascular coagulation in sepsis, and long pentraxin 3 (PTX3) enhances the lipopolysaccharide (LPS)-induced transcription of TF. The aim of this study was to study the mechanism by which complement and CD14 affects LPS- and Escherichia coli (E. coli)-induced coagulation in human blood. Fresh whole blood was anti-coagulated with lepirudin, and incubated with ultra-purified LPS (100 ng/ml) or with E. coli (1 × 10(7) /ml). Inhibitors and controls included the C3 blocking peptide compstatin, an anti-CD14 F(ab')2 antibody and a control F(ab')2 . TF mRNA was measured using quantitative polymerase chain reaction (qPCR) and monocyte TF surface expression by flow cytometry. TF functional activity in plasma microparticles was measured using an amidolytic assay. Prothrombin fragment F 1+2 (PTF1.2) and PTX3 were measured by enzyme-linked immunosorbent assay (ELISA). The effect of TF was examined using an anti-TF blocking antibody. E. coli increased plasma PTF1.2 and PTX3 levels markedly. This increase was reduced by 84->99% with compstatin, 55-97% with anti-CD14 and > 99% with combined inhibition (P < 0·05 for all). The combined inhibition was significantly (P < 0·05) more efficient than compstatin and anti-CD14 alone. The LPS- and E. coli-induced TF mRNA levels, monocyte TF surface expression and TF functional activity were reduced by > 99% (P < 0·05) with combined C3 and CD14 inhibition. LPS- and E. coli-induced PTF1.2 was reduced by 76-81% (P < 0·05) with anti-TF antibody. LPS and E. coli activated the coagulation system by a complement- and CD14-dependent up-regulation of TF, leading subsequently to prothrombin activation.

C1-inhibitor efficiently inhibits Escherichia coli-induced tissue factor mRNA up-regulation, monocyte tissue factor expression and coagulation activation in human whole blood

Both the complement system and tissue factor (TF), a key initiating component of coagulation, are activated in sepsis, and cross-talk occurs between the complement and coagulation systems. C1-inhibitor (C1-INH) can act as a regulator in both systems. Our aim in this study was to examine this cross-talk by investigating the effects of C1-INH on Escherichia coli-induced haemostasis and inflammation. Fresh human whole blood collected in lepirudin was incubated with E. coli or ultrapurified E. coli lipopolysaccharide (LPS) in the absence or presence of C1-INH or protease-inactivated C1-INH. C3 activation was blocked by compstatin, a specific C3 convertase inhibitor. TF mRNA was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and TF surface expression was measured by flow cytometry. In plasma, the terminal complement complex, prothrombin F1·2 (PTF1·2) and long pentraxin 3 (PTX3) were measured by enzyme-linked immunosorbent assay (ELISA). Cytokines were analysed using a multiplex kit. C1-INH (1·25-5 mg/ml) reduced both LPS- and E. coli-induced coagulation, measured as a reduction of PTF1·2 in plasma, efficiently and dose-dependently (P < 0·05). Both LPS and E. coli induced marked up-regulation of TF mRNA levels and surface expression on whole blood monocytes. This up-regulation was reduced efficiently by treatment with C1-INH (P < 0·05). C1-INH reduced the release of PTX3 (P < 0·05) and virtually all cytokines measured (P < 0·05). Complement activation was inhibited more efficiently with compstatin than with C1-INH. C1-INH inhibited most of the other readouts more efficiently, consistent with additional non-complement-dependent effects. These results indicate that complement plays a role in activating coagulation during sepsis and that C1-INH is a broad-spectrum attenuator of the inflammatory and haemostatic responses.

The effects of selective complement and CD14 inhibition on the E. coli-induced tissue factor mRNA upregulation, monocyte tissue factor expression, and tissue factor functional activity in human whole blood

BACKGROUND

The complement pathway and CD14 play essential roles in inflammation, but little is known about the relative roles of complement and CD14 in E. coli-induced tissue factor (TF) mRNA upregulation, expression by monocytes, and functional activity in human whole blood.

METHODS

Whole E. coli bacteria were incubated for up to 4 h in human whole blood containing the anticoagulant lepirudin, which does not affect complement activation. TF mRNA levels were analyzed using reverse transcription, quantitative real-time PCR (RT-qPCR), and the expression of TF on the cell surface was analyzed using flow cytometry. Complement was selectively inhibited using the C3 convertase inhibitor compstatin or a C5a receptor antagonist (C5aRa), while CD14 was blocked by an anti-CD14 F(ab')2 monoclonal antibody.

RESULTS

The E. coli-induced TF mRNA upregulation was reduced to virtually background levels by compstatin, whereas anti-CD14 had no effect. Monocyte TF expression and TF activity in plasma microparticles were significantly reduced by C5aRa. Anti-CD14 alone only slightly reduced E. coli-induced monocyte TF expression but showed a modest additive effect when combined with the complement inhibitors. Inhibiting complement and CD14 efficiently reduced the expression of the E. coli-induced cytokines IL-1beta, IL-6, IL-8, and platelet-derived growth factor bb.

CONCLUSION

Our results indicate that E. coli-induced TF mRNA upregulation is mainly dependent on complement activation, while CDI4 plays a modest role in monocyte TF expression and the plasma TF activity in human whole blood.

Differential effect of inhibiting MD-2 and CD14 on LPS- versus whole E. coli bacteria-induced cytokine responses in human blood

BACKGROUND

Sepsis is a major world-wide medical problem with high morbidity and mortality. Gram-negative bacteria are among the most important pathogens of sepsis and their LPS content is regarded to be important for the systemic inflammatory reaction. The CD14/myeloid differentiation factor 2 (MD-2)/TLR4 complex plays a major role in the immune response to LPS . The aim of this study was to compare the effects of inhibiting MD-2 and CD14 on ultra-pure LPS - versus whole E. coli bacteria-induced responses.

METHODS

Fresh human whole blood was incubated with upLPS or whole E. coli bacteria in the presence of MD-2 or CD14 neutralizing monoclonal antibodies, or their respective controls, and/or the specific complement-inhibitor compstatin. Cytokines were measured by a multiplex (n = 27) assay. NFκB activity was examined in cells transfected with CD14, MD-2 and/or Toll-like receptors.

RESULTS

LPS-induced cytokine response was efficiently and equally abolished by MD-2 and CD14 neutralization. In contrast, the response induced by whole E. coli bacteria was only modestly reduced by MD-2 neutralization, whereas CD14 neutralization was more efficient. Combination with compstatin enhanced the effect of MD-2 neutralization slightly. When compstatin was combined with CD14 neutralization, however, the response was virtually abolished for all cytokines, including IL-17, which was only inhibited by this combination. The MD-2-independent effect observed for CD14 could not be explained by TLR2 signaling.

CONCLUSION

Inhibition of CD14 is more efficient than inhibition of MD-2 on whole E. coli-induced cytokine response, suggesting CD14 to be a better target for intervention in Gram-negative sepsis, in particular when combined with complement inhibition.

The protective effect of amifostine on ultraviolet B-exposed xeroderma pigmentosum mice

Background:

Amifostine is a pharmaceutical agent that is used clinically to counteract the side-effects of chemotherapy and radiotherapy. It acts as a free radical scavenger that protects against harmful DNA cross-linking. The purpose of this study was to determine the effect of amifostine on the development of skin cancer in xeroderma pigmentosum (XP) mice exposed to ultraviolet B radiation (UVB).

Methods:

Twenty-five XP mice were equally divided into five groups. Group 1 (control) received no amifostine and no UVB exposure. Group 2 also received no amifostine, but was exposed to UVB at a dose of 200 mJ/cm² every other day. The remaining groups were subjected to the same irradiation, but were given amifostine at a dose of 50 mg/kg (group 3), 100 mg/kg (group 4), or 200 mg/kg (group 5) immediately prior to each exposure.

Results:

No tumours were seen in the control group. The animals in group 2 (no amifostine) developed squamous cell carcinoma (SCC) at 3.5–4.5 months (mean 3.9 months). Groups 3 and 4 (low- and medium-dose amifostine) developed SCC at 4.0–7.0 months (mean 5.3 months), representing a statistically significant delay in tumour presentation (p = 0.04). An even greater delay was seen in group 5 (high-dose amifostine), which developed SCC at 7.0–9.0 months (mean 8.5 months, p < 0.001 versus groups 3 and 4). Ocular keratitis developed in all animals except the unexposed controls and the high-dose treatment group.

Conclusion:

Treatment with amifostine significantly delays the onset of skin cancer and prevents ocular keratitis in UVB-exposed XP mice.

Demographic characteristics and survival with AIDS: health disparities in Chicago, 1993-2001

OBJECTIVES

We examined correlations between survival and race/ethnicity, age, and gender among persons who died from AIDS-related causes.

METHODS

We estimated survival among 11 022 persons at 12, 36, and 60 months after diagnosis with AIDS in 1993 through 2001 and reported through 2003 to the Chicago Department of Public Health. We estimated hazard ratios (HRs) by demographic and risk characteristics.

RESULTS

All demographic groups had higher 5-year survival rates after the introduction of highly active retroviral therapy (1996-2001) than before (1993-1995). The HR for non-Hispanic Blacks to Whites was 1.18 in 1993 to 1995 and 1.51 (P < .01) in 1996 to 2001. The HR for persons 50 years or older to those younger than 30 years was 1.63 in 1993-1995 and 2.28 (P < .01) in 1996-2001. The female-to-male HR was 0.90 in 1993-1995 and 1.20 (P < .02) in 1996-2001.

CONCLUSIONS

The risk of death was higher for non-Hispanic Blacks and Hispanics than for non-Hispanic Whites. Interventions are needed to increase early access to care for disadvantaged groups.

Diagnostic evaluation of newly arrived asymptomatic refugees with eosinophilia

BACKGROUND

Refugees may arrive for resettlement with asymptomatic parasitic infections, and eosinophilia may be the only clue to the presence of infection. Our aim was to determine the prevalence of eosinophilia and develop a standardized approach to the evaluation of asymptomatic refugees with eosinophilia.

METHODS

We reviewed the medical records of refugees seen from October 1998 through May 2002 at Boston Medical Center. Data examined included age, country of origin, absolute eosinophil count, results of stool ova and parasite testing, and results of serological testing for Strongyloides stercoralis, Schistosoma species, and filaria.

RESULTS

Eosinophilia--defined as an absolute eosinophil count of >or=450 cells/microL--was present in 266 (12%) of 2224 refugees. Patients with eosinophilia ranged in age from 2 months to 81 years and had arrived from Africa, Eastern Europe, Southeast Asia, South America, the Caribbean, and the Middle East. Absolute eosinophil counts ranged from 450 to 3224 cells/microL. Pathogens were identified in stool samples of 76 (29%) of 265 patients. Serological testing for S. stercoralis, Schistosoma species, and/or filaria was done for 120 (45%) of 266 patients. Results of serological testing were positive for S. stercoralis in 45 (39%) of 115 patients, for Schistosoma species in 15 (22%) of 67 patients, and for filaria in 18 (51%) of 35 patients. Serological evidence of parasitic infection was seen at all levels of eosinophilia and in patients with and without pathogens identified in their stool samples.

CONCLUSIONS

Systematic evaluation for parasites in asymptomatic, newly arrived refugees with eosinophilia should include stool ova and parasite examination, serological examination for S. stercoralis for all patients, and serological examination for Schistosoma species and filaria in patients from regions where these organisms are endemic.

Intrapulmonary percussive ventilation vs incentive spirometry for children with neuromuscular disease

BACKGROUND

Pulmonary infections can be life threatening for children with neuromuscular diseases who have impaired ability to clear secretions. Intrapulmonary percussive ventilation (IPV) is a pneumatic device that delivers air and aerosol to the lungs at frequencies of 200 to 300 cycles per minute at peak pressures from 20 to 40 cm H(2)O. Anecdotal reports and pilot studies show its safety and effectiveness in mobilizing secretions in patients with cystic fibrosis.

OBJECTIVE

To test the hypothesis that IPV used in a pulmonary program for adolescents with neuromuscular disease would reduce the number of days of antibiotic use for pulmonary infection.

METHODS

A randomized, controlled study was conducted to compare efficacy of IPV with incentive spirometry (IS) in reducing number of days of antibiotic use in adolescents with neuromuscular disease. The secondary endpoints were the number of respiratory infections, hospitalizations, and school days missed.

RESULTS

A total of 18 patients were enrolled (9 IPV, 9 IS). Antibiotic use was significantly higher with IS (24/1000 patient-days) compared with IPV (0/1000 patient-days), (incidence rate ratio, 43; 95% confidence interval, 6-333). The IS group spent more days hospitalized (4.4/1000 patient-days vs 0/1000 patient-days) than the IPV group (incidence rate ratio, 8.5; 95% confidence interval, 1.1-67). The IPV group had 0 episodes of pneumonia or bacterial bronchitis compared with 3 events in the IS group, although this did not meet statistical significance.

CONCLUSION

Intrapulmonary percussive ventilation as part of a preventive pulmonary regimen reduced days of antibiotic use and hospitalization for respiratory illness in adolescents with neuromuscular disease.

Comparison of varicella history with presence of varicella antibody in refugees

OBJECTIVE

To compare history of varicella with presence of varicella antibody in refugees and to determine the number of unnecessary doses of varicella vaccine administered to refugee children > or =7 years of age.

METHODS

Cross-sectional study of refugees > or =7 years of age evaluated between July 2000 and October 2002 by the Refugee Health Assessment Program at Boston Medical Center. We recorded age, sex, region of origin, varicella history, and results of serologic testing for presence of varicella antibodies.

RESULTS

Eighty-eight percent of individuals with a positive history of clinical varicella had varicella antibody; 65% of those with negative history had varicella antibody. The positive predictive value of a history of clinical varicella was 88%. The negative predictive value of a negative history was 39%.

CONCLUSION

History of varicella was not a reliable predictor of presence or absence of varicella antibody in refugees. Strategies to protect individuals with negative histories of clinical varicella include immediate immunization or serotesting followed by immunization of susceptible individuals. Relying on positive histories of clinical varicella may leave some individuals susceptible to varicella and impede efforts to eliminate varicella in the US.

Assessing missed opportunities for HIV testing in medical settings

BACKGROUND

Many HIV-infected persons learn about their diagnosis years after initial infection. The extent to which missed opportunities for HIV testing occur in medical evaluations prior to one's HIV diagnosis is not known.

DESIGN

We performed a 10-year retrospective chart review of patients seen at an HIV intake clinic between January 1994 and June 2001 who 1). tested positive for HIV during the 12 months prior to their presentation at the intake clinic and 2). had at least one encounter recorded in the medical record prior to their HIV-positive status. Data collection included demographics, clinical presentation, and whether HIV testing was recommended to the patient or addressed in any way in the clinical note. Prespecified triggers for physicians to recommend HIV testing, such as specific patient characteristics, symptoms, and physical findings, were recorded for each visit. Multivariable logistic regression was used to identify factors associated with missed opportunities for discussion of HIV testing. Generalized estimating equations were used to account for multiple visits per subject.

RESULTS

Among the 221 patients meeting eligibility criteria, all had triggers for HIV testing found in an encounter note. Triggers were found in 50% (1702/3424) of these 221 patients' medical visits. The median number of visits per patient prior to HIV diagnosis to this single institution was 5; 40% of these visits were to either the emergency department or urgent care clinic. HIV was addressed in 27% of visits in which triggers were identified. The multivariable regression model indicated that patients were more likely to have testing addressed in urgent care clinic (39%), sexually transmitted disease clinic (78%), primary care clinics (32%), and during hospitalization (47%), compared to the emergency department (11%), obstetrics/gynecology (9%), and other specialty clinics (10%) (P <.0001). More recent clinical visits (1997-2001) were more likely to have HIV addressed than earlier visits (P <.0001). Women were offered testing less often than men (P =.07).

CONCLUSIONS

Missed opportunities for addressing HIV testing remain unacceptably high when patients seek medical care in the period before their HIV diagnosis. Despite improvement in recent years, variation by site of care remained important. In particular, the emergency department merits consideration for increased resource commitment to facilitate HIV testing. In order to detect HIV infection prior to advanced immunosuppression, clinicians must become more aware of clinical triggers that suggest a patient's increased risk for this infection and lower the threshold at which HIV testing is recommended.

Health-related quality of life of patients with HIV disease: impact of hepatitis C coinfection

Health-related quality of life (HRQOL) is diminished in patients infected with both hepatitis C virus (HCV) and human immunodeficiency virus (HIV), but the effect of HIV/HCV coinfection on HRQOL is unknown. We compared the HRQOL of urban HIV/HCV coinfected patients with that of patients infected with either HCV or HIV alone. We then compared the 3 groups with a US population sample, adjusting for demographic characteristics. HRQOL for the group of HIV/HCV coinfected patients was statistically similar to that of HRQOL in patients with either HCV or HIV alone, but the 3 groups had a significantly decreased HRQOL than did the adjusted US population. Using multivariate techniques, we determined that age, unemployment, injection drug use, and depression were associated with impaired HRQOL. These findings underscore the importance of a multidisciplinary approach to the treatment of these patient populations.

Self-assessment of tuberculosis infection risk by urban adolescents

OBJECTIVE

To examine self-reported risks for tuberculosis (TB) infection relative to recalled receipt of TB risk assessments and skin testing in a cohort of urban adolescents.

DESIGN, SETTING, AND PARTICIPANTS

Survey of ninth graders and their parents from 3 inner-city public high schools. Students and parents were asked about TB infection risk factors, frequency of routine health maintenance visits, TB risk assessments, and TB skin testing. Students were surveyed in schools and asked to take home surveys for their parents to complete.

RESULTS

Of 578 students (95.4% response rate), 436 (75.4%) claimed at least 1 TB infection risk factor. Although 468 (81.0%) of the students reported having a regular checkup within the past year, only 128 (22.1%) recalled being asked TB risk assessment questions and only 231 (40.0%) recalled undergoing skin testing during the previous year. Parent response rates were low (n = 207; 34.2% response rate), and parents of students attending bilingual classes were overrepresented among responders. There were no significant relationships between self-indicating a risk for TB infection and self-recollection of having undergone TB screening, having had a tuberculin skin test placed, or having had a regular checkup, with the exception that students who responded that they lived with a tuberculin skin test-positive person were 38% less likely to recall having had a tuberculin skin test themselves (n = 21; 95% confidence interval, 24%-50%). The level of agreement between student and parent responses in the 207 survey pairs available for analysis ranged from poor to good (kappa = 0.07-0.61) on individual questions.

CONCLUSIONS

These observations suggest that most at-risk adolescents in this city are not being adequately screened for TB infection. Programs to improve health care provider acceptance of targeted testing principles or to reengage in school-based screening of students with certain risk factors seem necessary.

Cost-effectiveness of serotesting compared with universal immunization for varicella in refugee children from six geographic regions

BACKGROUND

It is unknown whether it is more cost-effective to test for varicella antibody or to immunize without testing in immigrant populations. The reliability of history of varicella disease is also unclear.

METHODS

The prevalences of varicella antibody in immigrant children from six regions of the world were used in a cost-effectiveness model to calculate the antibody prevalence above which it is more cost-effective to test rather than to immunize. History of varicella disease was obtained from chart review. We calculated the positive and negative predictive values of varicella history by age group and region.

RESULTS

The prevalence of varicella antibody above which it is more cost-effective to test than to immunize was 34% for children less than 13 years old and 17% for those aged 13 years and older. Overall, the positive predictive value of varicella history was 93-100% and the negative predictive value of varicella history was 28-66% among the six geographic regions.

CONCLUSION

Immunization without serotesting was cost-effective in children <5 years of age. Testing prior to immunization was cost-effective in children 5 years of age and older. History of varicella was a good predictor of the presence of antibody to varicella, whereas a negative history was a poor predictor of the absence of antibody to varicella.

Screening for sexually transmitted infections in substance abuse treatment programs

OBJECTIVES

We evaluated the prevalence of the sexually transmitted infections (STIs) chlamydia and gonorrhea in clients at a methadone maintenance program and a residential detoxification program.

METHODS

We collected urine specimens for chlamydia and gonorrhea ligase chain reaction testing and assessed sexual, substance abuse and STI histories.

RESULTS

Of 700 subject assessments, 490 occurred among detoxification clients and 210 in methadone maintenance. Chlamydia trachomatis was detected in 5/700 (0.9, 95% CI=0.1-1.8%) and Neisseria gonorrhoeae in none. All chlamydia infected subjects were recruited from the detoxification program. Subjects reported high risk sexual behavior: 17% reported commercial sex exchange, and 22% reported inconsistent condom use with multiple sexual partners during the prior 2 months.

CONCLUSION

Based on prevalence in Boston, MA, universal screening for STI in substance abuse treatments programs is not warranted. However, routine screening for younger substance abusers and in communities with high prevalence should be considered.

Seroprevalence of measles, rubella, and varicella in refugees

Immigrant children who enter the United States without immunization records may be required to receive vaccines for diseases to which they are already immune or for which they have previously received immunization. We tested 669 newly arrived refugees (age range, 0-20 years) for antibody to measles, rubella, and varicella, to determine the seroprevalence of antibodies to these diseases in this group of immigrants. Five hundred forty-nine (82%) of 669 patients had antibody to measles, 545 (82%) of 668 had antibody to rubella, and 430 (64%) of 668 had antibody to varicella. Antibody to all 3 diseases increased with increasing age. No clinically significant differences in presence of antibody were noted by region of origin.

The role of mineral in the storage of elastic energy in turkey tendons

Mammals elastically store energy in leg and foot tendons during locomotion. In the turkey, much of the force generated by the gastrocnemius muscle is stored as elastic energy during tendon deformation and not within the muscle. During growth, avian tendons mineralize in the portions distal to the muscle and show increased tensile strength and modulus as a result. The purpose of this study was to evaluate the viscoelastic behavior of turkey tendons and self-assembled collagen fiber models to determine the molecular basis for tendon deformation. The stress-strain behavior of tendons and self-assembled collagen fibers was broken into elastic and viscous components. The elastic component was found to be to a first approximation independent of source of the collagen and to depend only on the extent of cross-linking. In the absence of cross-links the elastic component of the stress was found to be negligible for self-assembled type I collagen fibers. In the presence of cross-links the behavior approached that found for mineralized turkey tendons. The elastic constant for turkey tendon was shown to be between 5 and 7.75 GPa while it was about 6.43 GPa for self-assembled collagen fibers aged for 6 months at 22 degrees C. The viscous component for mineralized turkey tendons was about the same as that of self-assembled collagen fibers aged for 6 months, a result suggesting that addition of mineral does not alter the viscous properties of tendon. It is concluded that elastic energy storage in tendons involves direct stretching of the collagen triple-helix, nonhelical ends, and cross-links between the molecules and is unaffected by mineralization. Furthermore, it is hypothesized that mineralization of turkey tendons is an efficient means of preserving elastic energy storage while providing for increased load-bearing ability required for locomotion of adult birds.

Evidence for distinct complement regulatory and measles virus binding sites on CD46 SCR2

Human CD46, or membrane cofactor protein, is a regulator of complement activation and is used as a cellular receptor by measles virus. Using a series of 13 single point mutants, the region of short consensus repeat (SCR) 2 domain involved in the regulation of complement activation was mapped to residues E84, N94, Y98, E102, E103, I104 and E108. Molecular modelling localized all residues, with the exception of E84, close to each other on the external lateral face of the molecule, away from the residues important for the binding of measles virus, which are localized on the top of the molecule. The E84 residues is localized in the SCR1-2 hinge and the deleterious effect of its substitution by an alanine residue could affect the relative orientation and / or tilt of SCR1 on SCR2. Taken together, the results suggest that the measles virus binding and cofactor activity of CD46 map to distinct areas on the SCR2 module.

A therapeutic human anti-idiotypic antibody mimics CD55 in three distinct regions

The human anti-idiotypic antibody 105AD7 was isolated from a colorectal cancer patient receiving the anti-tumor antibody 791T/36 for radioimmuno-scintigraphy of liver metastases. We have mapped the binding site of 791T/36 to the first two small consensus repeat (SCR) domains of the complement regulatory protein (CD55) that is overexpressed by a wide range of solid tumors. Cloning of both antigen and anti-idiotype has identified the molecular basis of their mimicry. Amino acid homology has been identified between three complementarity-determining regions of 105AD7 and three regions of CD55 within the first two SCR domains. 791T/36 and anti-anti-idiotypic (Ab3) polyclonal antibodies raised against 105AD7 showed specific binding to these peptides. The antibodies were also found to bind synergistically to combinations of these peptides, indicating cooperativity between the peptides in stabilizing antibody binding. This also implies that the contact face on both CD55 antigen and 105AD7 is generated by the cooperation of several peptides positioned on two domains in each protein. Thus a human monoclonal anti-idiotypic antibody generated by a cancer patient is able to show both amino acid and structural homology with the complement regulatory protein CD55. These findings help identify the mechanism by which a human anti-idiotypic antibody is able to mimic a tumor-associated antigen and stimulate anti-tumor B and T cell responses.

Chimeric CD46/DAF molecules reveal a cryptic functional role for SCR1 of DAF in regulating complement activation

Chimeric proteins using membrane cofactor (CD46) and decay accelerating factor (DAF or CD55) were generated to further investigate the functional domains involved in the regulation of human serum complement. Following activation of the classical pathway, the isolated substitution of CD46 SCR III (x3DAF) exhibited a modest regulatory activity comparable to that of CD46. The isolated substitution of CD46 SCR IV (x4DAF), and the combined CD46 SCR III+IV substitutions (x3/4DAF) were essentially as efficient as DAF. No regulation of C3b deposition was observed with the combined CD46 SCR I+II substitutions (x1/2DAF). When tested after activation of the alternative pathway, both the x3DAF and x3/4DAF chimeras failed to regulate C3b deposition, while the x4DAF chimera still displayed some activity. In contrast to that observed following classical pathway activation, the x1/2DAF chimera exhibited a similar efficiency to wild type CD46 and DAF in controlling C3b deposition. Using SCR specific antibodies, the regulatory activity of the x1/2DAF chimera against the alternative pathway was mapped to the first three distal SCR (i.e. DAF 1, DAF 2 and CD46 III). These data demonstrate that several combinations of SCR domains from two related complement regulators can result in functional molecules, and reveal a novel and cryptic functional role for DAF SCR1.

Octamerization enables soluble CD46 receptor to neutralize measles virus in vitro and in vivo

A chimeric fusion protein encompassing the CD46 ectodomain linked to the C-terminal part of the C4b binding protein (C4bp) alpha chain (sCD46-C4bpalpha) was produced in eukaryotic cells. This protein, secreted as a disulfide-linked homo-octamer, was recognized by a panel of anti-CD46 antibodies with varying avidities. Unlike monomeric sCD46, the octameric sCD46-C4bpalpha protein was devoid of complement regulatory activity. However, sCD46-C4bpalpha was able to bind to the measles virus hemagglutinin protein expressed on murine cells with a higher avidity than soluble monomeric sCD46. Moreover, the octameric sCD46-C4bpalpha protein was significantly more efficient than monomeric sCD46 in inhibiting virus binding to CD46, in blocking virus induced cell-cell fusion, and in neutralizing measles virus in vitro. In addition, the octameric sCD46-C4bpalpha protein, but not the monomeric sCD46, fully protected CD46 transgenic mice against a lethal intracranial measles virus challenge.

Interaction of CD46 with measles virus: accessory role of CD46 short consensus repeat IV

To define further the accessory role(s) of the CD46 (membrane cofactor protein) short consensus repeat (SCR) III and IV domains in the interaction of CD46 with measles virus (MV), chimeric proteins were generated by substituting domains from the structurally related protein decay accelerating factor (DAF, CD55): x3DAF (exchange of CD46 SCR III) and x4DAF (exchange of SCR IV). Transfected CHO cell lines that stably expressed these chimeric proteins were compared for MV binding and infection. Compared with wild-type CD46 (I-II-III-IV), a significant decrease in MV binding was observed with x4DAF. Despite this limited binding, these cells were still capable of supporting virus entry. In a quantitative fusion assay, no significant differences in fusion were observed as a result of the exchange of either CD46 SCR III or IV. However, the down-regulation of cell surface CD46 typically observed following MV infection was abolished with x4DAF, as was the redistribution of CD46 on the cell surface. Thus, CD46 SCR IV appears to be required for optimal virus binding and receptor down-regulation, although importantly, in spite of these functional limitations, x4DAF can still be used for MV entry.

Inhibition of hyperacute transplant rejection by soluble proteins with the functional domains of CD46 and FcgammaRII

BACKGROUND

Recombinant soluble forms of complement regulatory molecules, including the human complement regulatory protein CD46 (rsCD46), have been shown to inhibit hyperacute transplant rejection (HAR) and protect against complement-mediated inflammatory tissue damage. Similarly, recombinant soluble forms of the immunoglobulin receptor FcgammaRII (rsFcgammaRII) can attenuate antibody-mediated inflammatory responses. We have produced and tested the function of novel recombinant chimeric proteins that incorporate the functional domains of both CD46 (membrane cofactor protein, MCP) and the low affinity human IgG receptor FcgammaRII (CD32).

METHODS

Two recombinant soluble chimeric proteins (CD46:FcR and FcR:CD46) were designed and produced using a human cell expression system. Their ability to protect cells against complement-mediated lysis (through the CD46 domain) and bind human IgG (through the Fc receptor domain) was assessed in vitro. They were also tested in vivo in the rat reverse passive Arthus reaction and a murine model of hyperacute cardiac transplant rejection.

RESULTS

In vitro, the functional domains of the chimeric proteins each retained their activity. In vivo, the serum half-life of the recombinant chimeric proteins in mice was more than either rsCD46 or rsFcgammaRII. In the rat reverse passive Arthus reaction, intradermal injection of each recombinant protein substantially reduced inflammatory skin edema (>50%) and polymorphonuclear neutrophil infiltration (>90%). In the hyperacute rejection model, i.v. treatment with FcR:CD46 prevented complement-mediated rejection, macroscopic bruising, edema, and thrombosis more effectively than rsCD46.

CONCLUSIONS

CD46/FcgammaRII bifunctional proteins have an improved ability to control complement-mediated hyperacute graft rejection and have therapeutic potential in other conditions involving antibody-mediated inflammation.

CD46 (membrane cofactor protein) associates with multiple beta1 integrins and tetraspans

The tetraspans associate with a large number of surface molecules, including a subset of beta1 integrins and, indirectly through CD19, with the complement receptor CD21. To further characterize the tetraspan complexes we have raised and selected monoclonal antibodies (mAb) for their ability to immunoprecipitate a molecule associated with CD9. A unique mAb was identified which recognizes the complement regulator CD46 (membrane cofactor protein). CD46 associated in part with several tetranspans and with all beta1 integrins that were tested (CD29/CD49a, CD29/CD49b, CD29/CD49c, CD29/CD49e, CD29/CD49f) but not with beta4 integrins. These data, together with cross-linking experiments showing the existence in living cells of CD46/integrin complexes, suggest that CD46 associates directly with beta1 integrins and indirectly with tetraspans. CD46 also acts as a receptor for measles virus; however, mAb to various integrins and tetraspans did not modify the virus fusion entry step.

Platelet compatibility of an artificial surface modified with functionally active heparin

Platelet compatibility after coating an artificial material with functionally active heparin was investigated. Blood was circulated in uncoated or heparin coated PVC tubing. In one hour platelet counts decreased from 155 (113-184)x10(9)/l to 124 (100-148)x10(9)/l with uncoated compared to 164 (132-192)x10(9)/l with heparin coated tubing (intergroup p = 0.02). Beta-thromboglobulin increased from 116 (80-148) microg/l to 1039 (757-1298) microg/l with uncoated and to 352 (229-638) microg/l with heparin coated tubing (intergroup p = 0.005). Platelet counts and beta-thromboglobulin correlated closely with complement activation. Solid-phase enzyme immunoassay demonstrated substantial deposition of CD42a/GPIbIX and CD61/GPIIIa on uncoated, but not on heparin coated tubing (intergroup p<0.0005). Scanning electron microscopy demonstrated activated platelets and aggregates on uncoated in contrast to heparin coated tubing, where scattered, unactivated platelets were found. Changes in P-selectin and microparticles were minor. In conclusion, this heparin surface substantially improved platelet compatibility. Markers of choice for in vitro evaluation were platelet counts, beta-thromboglobulin and platelet deposition.

Control of C3b and C5b deposition by CD46 (membrane cofactor protein) after alternative but not classical complement activation

C3b and C5b deposition following complement activation, and its regulation by CD46 were studied using xenogenic Chinese hamster ovary (CHO) cells as targets and cytofluorometry. Following activation of the alternative pathway, an initial low level of C3b deposition was observed on CHO cell surfaces after a lag time of approximately 4 min. This was followed by a secondary high level of C3b deposition with a slower rate. C3b deposition was maximal within 15 min. When CD46 was expressed (B2 isoform), the kinetics of C3b deposition were essentially unchanged, but the onset of the secondary high C3b deposition was fully prevented. C5b deposition was also observed on CHO but not on CHO.CD46 cells following activation of the alternative pathway. Activation of the classical pathway on CHO and CHO.CD46 cells, using factor B-depleted human serum and anti-CHO antibodies, resulted in almost identical single-peak C3b deposition profiles. Accordingly, no regulation of C5b deposition by CD46 was evident following activation of the classical pathway. These data indicate that CD46 prevents the C3b deposition amplification loop mediated by the alternative C3 convertase and, consequently, inhibits the formation of the alternative C5 convertase. But CD46 prevents neither the spontaneous tick-over C3b deposition leading to the formation of the alternative C3 convertase nor the formation of the functional classical C3 and C5 convertases.