Assessment of humoral immune response to different COVID-19 vaccines in patients undergoing maintenance hemodialysis

INTRODUCTION

The immune response to different Coronavirus Disease 2019 (COVID-19) vaccines is under-investigated in end-stage kidney disease (ESKD) patients, especially in the Middle East and North Africa. We carried out this research to estimate the effectiveness of COVID-19 immunization in ESKD patients on regular hemodialysis (HD).

METHODS

In this prospective observational study, we enrolled 60 ESKD patients on regular HD who had completed COVID-19 vaccination and 30 vaccinated healthy participants. Serum levels of severe acute respiratory syndrome coronavirus 2 immunoglobulin G (SARS-COV2 IgG) were quantified 1 month after completing the vaccination schedule, and all participants were followed up from October 2021 to March 2022. The vaccines used in the study were from Pfizer-BioNTech, AstraZeneca, and Sinopharm.

RESULTS

The median level of SARS-COV2 IgG was lower in HD patients than in healthy participants (p < 0.001). Regarding the type of COVID-19 vaccination, there was no statistical difference in SARS-COV2 IgG levels among HD patients. During the observation period, none of the HD patients had COVID-19.

CONCLUSION

COVID-19 vaccination appeared to be protective in HD patients for 6 months and the side effects of vaccines were tolerable.

Differences in the immunoglobulin gene repertoires of IgG versus IgA multiple myeloma allude to distinct immunopathogenetic trajectories

The analysis of the immunogenetic background of multiple myeloma (MM) has proven key to understanding disease ontogeny. However, limited information is available regarding the immunoglobulin (IG) gene repertoire in MM cases carrying different heavy chain isotypes. Here, we studied the IG gene repertoire in a series of 523 MM patients, of whom 165 and 358 belonged to the IgA and IgG MM groups, respectively. IGHV3 subgroup genes predominated in both groups. However, at the individual gene level, significant (p<0.05) differences were identified regarding IGHV3-21 (frequent in IgG MM) and IGHV5-51 (frequent in IgA MM). Moreover, biased pairings were identified between certain IGHV genes and IGHD genes in IgA versus IgG MM. Turning to the imprints of somatic hypermutation (SHM), the bulk of rearrangements (IgA: 90.9%, IgG: 87.4%) were heavily mutated [exhibiting an IGHV germline identity (GI) <95%]. SHM topology analysis disclosed distinct patterns in IgA MM versus IgG MM cases expressing B cell receptor IG encoded by the same IGHV gene: the most pronounced examples concerned the IGHV3-23, IGHV3-30 and IGHV3-9 genes. Furthermore, differential SHM targeting was also identified between IgA MM versus IgG MM, particularly in cases utilizing certain IGHV genes, alluding to functional selection. Altogether, our detailed immunogenetic evaluation in the largest to-date series of IgA and IgG MM patients reveals certain distinct features in the IGH gene repertoires and SHM. These findings suggest distinct immune trajectories for IgA versus IgG MM, further underlining the role of external drive in the natural history of MM.

SARS-CoV-2-neutralizing humoral IgA response occurs earlier but modest and diminishes faster compared to IgG response

Secretory immunoglobulin A (IgA) plays a crucial role in the mucosal immunity for preventing the invasion of the exogenous antigens, however, little has been understood about the neutralizing activity of serum IgA. Here, to examine the role of IgA antibodies against COVID-19 illnesses, we determined the neutralizing activity of serum/plasma IgG and IgA purified from previously SARS-CoV-2-infected and COVID-19 mRNA-vaccine-receiving individuals. We found that serum/plasma IgA possesses substantial but rather modest neutralizing activity against SARS-CoV-2 compared to IgG with no significant correlation with the disease severity. Neutralizing IgA and IgG antibodies achieved the greatest activity at approximately 25 and 35 days after symptom onset, respectively. However, neutralizing IgA activity quickly diminished and went down below the detection limit approximately 70 days after onset, while substantial IgG activity was observed till 200 days after onset. The total neutralizing activity in sera/plasmas of those with COVID-19 largely correlated with that in purified-IgG and purified-IgA and levels of anti-SARS-CoV-2-S1-binding IgG and anti-SARS-CoV-2-S1-binding IgA. In individuals who were previously infected with SARS-CoV-2 but had no detectable neutralizing IgA activity, a single dose of BNT162b2 or mRNA-1273 elicited potent serum/plasma neutralizing IgA activity but the second dose did not further strengthen the neutralization antibody response. The present data show that the systemic immune stimulation with natural infection and COVID-19 mRNA-vaccines elicit both SARS-CoV-2-specific neutralizing IgG and IgA response in serum, but the IgA response is modest and diminishes faster compared to IgG response.

Author Summary

Immunoglobulin A (IgA) is the most abundant type of antibody in the body mostly located on mucosal surfaces as a dimeric secretory IgA. Such secretory IgA plays an important role in preventing the adherence and invasions of foreign objects by its neutralizing activity, while monomeric serum IgA is thought to relate to the phagocytic immune system activation. Here, we report that individuals with the novel coronavirus disease (COVID-19) developed both systemic neutralizing IgG and IgA active against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the neutralizing IgA response was quick and reached the highest activity 25 days post-symptom-onset, compared to 35 days for IgG response, neutralizing IgA activity was modest and diminished faster than neutralizing IgG response. In individuals, who recovered from COVID-19 but had no detectable neutralizing IgA activity, a single dose of COVID-19 mRNA-vaccine elicited potent neutralizing IgA activity but the second dose did not further strengthen the antibody response. Our study provides novel insights into the role and the kinetics of serum IgA against the viral pathogen both in naturally-infected and COVID-19 mRNA-vaccine-receiving COVID-19-convalescent individuals.

Seroprevalence and Dynamics of anti-SARS-CoV-2 antibody among healthcare workers following ChAdOx1 nCoV-19 vaccination

Health care workers (HCWs) are in a higher risk of acquiring the disease owing to their regular contact with the patients. The aim of this study is to evaluate the seroprevalence among HCWs pre- and post-vaccination. The serological assessment of anti-SARS-CoV-2 antibody was conducted in pre- and post-vaccination of first or both doses of the ChAdOx1 nCoV-19 vaccine and followed up to 8 months for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and antibody titre. The neutralising antibody was positively correlated with IgG and total antibody. IgG was significantly decreased after 4–6 months post-infection. Almost all HCWs developed IgG after 2 doses of vaccine with comparable IgG to that of the infected HCWs. A follow-up of 6 to 8 months post vaccination showed a significant drop in antibody titre, while 56% of them didn't show a detectable level of IgG, suggesting the need for a booster dose. Around 21% of the vaccinated HCWs with significantly low antibody titre were infected with the SARS-CoV-2, but a majority of them showed mild symptoms and recovered in home isolation without any O2 support. We noticed the effectiveness of the ChAdOx1 nCoV-19 vaccine as evident from the low rate of breakthrough infection with any severe symptoms.

Severe Acute Respiratory Syndrome Coronavirus 2 Antibodies Among Healthcare Workers After Vaccine Administration in an Intensive Care Unit

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease 2019 (COVID-19) emerged in China in December 2019. Healthcare workers (HCWs) are one of the high-risk groups of infection and knowledge of the seroprevalence of SARS-CoV-2 antibodies among this class is very important, not only to understand the spread of COVID-19 among health institutions but also to assess the success of public health interventions. The objective of this prospective study was to determine the seroprevalence of COVID-19 immunoglobulin G (IgG) antibodies after vaccine administration and assess the symptomatology associated with the number of IgG antibodies. A total of 75 HCWs from an intensive care unit were studied three and six months after the second administration of the COVID-19 vaccine. They were divided into three groups: IgG antibodies between 4,160 and 6,350 (group one), greater than 6,350 (group two), and less than 4,160 (group three). After the first administration of the vaccine, 80% had symptoms in both groups one and two, whereas only 13.8% had symptoms in group three. After the second dose of the vaccine, all elements of group one and 80% of group two developed symptoms, but only 40% of group three manifested symptoms. With the exception of one, all professionals showed a decrease in the number of IgG antibodies from three to six months. Our findings show that professionals with a higher number of IgG antibodies had more symptoms and that these rapidly declined over the three-to-six-month period.

A Prospective Study on Rapidly Declining SARS-CoV-2 IgG Antibodies Within One to Three Months of Testing IgG Positive: Can It Lead to Potential Reinfections?

Background COVID-19 immunoglobulin G (IgG) antibodies have been considered to provide protective immunity and its immunoassays have been widely used for serosurveillance. In our serosurveillance on an industrial workforce of randomly selected 3296 subjects, COVID-19 IgG antibody positivity was reported in 7.37% (243) subjects. However, when 30 days later, eight of the 243 COVID-19 IgG antibody-positive individuals complained of symptoms suggestive of COVID-19 infection and were confirmed as COVID-19 infection by reverse transcription-polymerase chain reaction (RT-PCR), their COVID-19 IgG antibodies were retested. Seven of the eight previously IgG positive individuals had lost their protective antibodies. Methods Subsequently, a prospective clinical trial was planned by repeating the test for IgG antibodies on the remaining earlier positive 235 individuals at 45-65 days after their initial test. Only 201 of the 235 individuals consented and participated in the non-randomized single-arm observational trial. Results Only 28.36% (57/201) retained their IgG antibodies and 70.15% (141/201) had lost their IgG antibodies. Three cases reported equivocal results on retesting. Conclusions Our findings show that the protective COVID-19 IgG antibodies rapidly decline over one to three months. Further studies are needed with a quantitative assay over a period with neutralizing antibodies to establish if its decay can potentially lead to reinfections. Rapidly decaying protective IgG antibodies would impact herd immunity and vaccine durability. It is critical for the potential vaccines to generate both protective T- and B-cell immune responses in a sustained manner.

A case report of a pregnant woman infected with coronavirus disease 2019 pneumonia

RATIONALE

Since the end of December 2019, the outbreak of coronavirus disease 2019 (COVID-19) epidemic has occurred and spread rapidly throughout China. At present, China's epidemic situation has been basically controlled, but the number of cases worldwide is increasing day by day. On March 11, the WHO officially announced that the COVID-19 had become a global pandemic. However, there are currently limited data on pregnant women with COVID-19 pneumonia and their infants. In this paper, a case of a pregnant woman infected with COVID-19 pneumonia is reported.

PATIENT CONCERNS

We report a clinically confirmed COVID-19 pregnant woman. The patient was tested negative 4 times in nucleic acid test, but immunoglobulin G was positive and immunoglobulin M was negative before delivery, suggesting a previous infection.

DIAGNOSES

The pregnant woman underwent a computed tomography scan of both lungs at 29 + 2 weeks of pregnancy, and scattered stiffness and frosted glass shadows of both lungs were observed. According to the diagnostic criteria for COVID-19 pneumonia in the "New Coronavirus Prevention and Control Plan Fifth Edition" of the National Health Commission of China, she was diagnosed as a clinically confirmed case.

INTERVENTIONS

The pregnant women received nebulized inhalation and oral cephalosporin treatment in a community hospital and was discharged after the symptoms disappeared. After that, she was isolated at home.

OUTCOMES

The pregnant woman gave birth to a healthy baby after being cured from COVID-19 infection. The nucleic acid test of the neonatal pharyngeal swab was negative, and the neonatal serum test showed positive for immunoglobulin G and negative for immunoglobulin M.

LESSONS SUBSECTIONS

The findings of this case report are useful for understanding the possible clinical features of COVID-19 infection in pregnant women, the duration of the antibody, and passive immunity of the fetus.

[Application of ultrasonography scoring system in the assessment of IgG4-related sialadenitis]

OBJECTIVE

To assess the diagnostic value of salivary gland ultrasonography (SGUS) for IgG4-related sialadenitis.

METHODS

Ultrasonography examination of major salivary glands was conducted for 48 IgG4-related sialadenitis patients and 50 Sjögren's syndrome patients, whose ages and disease duration were matched. The imaging features were graded using two different scoring systems (0-16 and 0-48, respectively) obtained from the grades of bilateral parotid and submandibular glands. The scores were used to further evaluate the features of salivary gland ultrasonography in IgG4-related sialadenitis and to compare them with Sjögren's syndrome patients. The association of SGUS scores of IgG4-related sialadenitis group with serological tests was analyzed.

RESULTS

The mean age of IgG4-related sialadenitis group and Sjögren's syndrome group was 49.23 years and 50.44 years, respectively. The serum IgG4 level of the patients in the IgG4-related sialadenitis group was increased, with an average (9.60±6.43) g/L. And the serum IgE level was at a median of 251.5 (123.4-543.6) IU/mL. In the 0-16 system, the scores of submandibular glands of the patients in IgG4-related sialadenitis and Sjögren's syndrome were 6.0 (6.0-8.0) and 4.0 (2.0-8.0), and the scores of the total four glands were 10.0 (8.0-14.0) and 8.0 (4.0-12.0) respectively. In the 0-48 system, the scores of submandibular glands with IgG4-related sialadenitis and Sjögren's syndrome were 18.0 (14.5-20.0) and 11.0 (7.0-14.0), and the scores of the total four glands were 26.0 (18.5-34.0) and 21.5 (15.0-26.3) respectively. It suggested that in the 0-16 system and the 0-48 system, scores of submandibular glands and the total of four glands of IgG4-related sialadenitis were higher than those of Sjögren's syndrome. Meanwhile, the association analysis of 0-48 system showed a positive correlation of SGUS scores with serum IgG4, which also showed a positive correlation of SGUS scores with serum IgE in 0-16 system.

CONCLUSION

Semi-quantitative ultrasonography scoring systems can evaluate and quantify the lesions of salivary glands, which can be helpful in the diagnosis and differential diagnosis of IgG4-related sialadenitis combined with the clinical manifestations, serological indicators and/or histopathological manifestations. Ultrasonography can also assess the activity of IgG4-related sialadenitis preliminarily.

Response to immune complex vaccine in chronic hepatitis B patients is associated with lower baseline level of serum IgG galactosylation

The composition of glycan in immunoglobulin G (IgG) has shown to affect various diseases and can be regulated by drugs and preventive vaccination. A hepatitis B surface antigen (HBsAg)-hepatitis B immunoglobulin (HBIG) immune complex (YIC) therapeutic vaccine for chronic hepatitis B (CHB) patients has undergone clinical trials. To explore for markers of CHB, which could be associated with responsiveness to YIC therapeutic vaccine, serum IgG glycosylation in CHB patients was analyzed.Kinetic changes of serum galactosylated IgG in 53 hepatitis Be antigen (HBeAg)-positive CHB patients treated with YIC were monitored by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) analysis. Whole blood cytokines were assayed by cytokine binding assay kits. All samples were back assayed before treatment, during therapy and follow-up for 6 months from a previous completed clinical trial.During YIC treatment, 26 patients with lower IgG galactosylation level at baseline [galactosylation level (Gal-ratio) = -0.29, 0.18 (mean, SD)] showed sustained increase of serum galactosylated IgG, and responded to YIC treatment by HBeAg seroconversion. While those who did not respond to YIC treatment [Gal-ratio = -0.40, 0.15 (mean, SD)] failed to show similar changes. Furthermore, this kinetic increase of galactosylated IgG correlated with marked up-regulated IL-2 level, confirming that effective cellular immune responses have participated in responsiveness.For HBeAg-positive CHB patients lower serum IgG galactosylation level may serve as an indicator for selecting a suitable subpopulation of candidates for YIC therapeutic vaccination.

Protein Corona: Prevention of Dominant IgG Adsorption on Nanocarriers in IgG‐Enriched Blood Plasma by Clusterin Precoating (Adv. Sci. 10/2019)

The development of nanocarriers for drug delivery is challenged by individual blood composition fluctuations. In article number 1802199, Svenja Morsbach and co‐workers report the accumulation of immunoglobulins in the protein corona of nanocarriers in IgG‐enriched blood plasma resulting in increased cell uptake. This could be prevented by pre‐coating the nanocarriers with the “stealth” protein clusterin. Cover design by Stefan Schuhmacher.

Application of transmission infrared spectroscopy and partial least squares regression to predict immunoglobulin G concentration in dairy and beef cow colostrum

The objective of this study was to explore the potential of transmission infrared (TIR) spectroscopy in combination with partial least squares regression (PLSR) for quantification of dairy and beef cow colostral immunoglobulin G (IgG) concentration and assessment of colostrum quality. A total of 430 colostrum samples were collected from dairy (n = 235) and beef (n = 195) cows and tested by a radial immunodiffusion (RID) assay and TIR spectroscopy. Colostral IgG concentrations obtained by the RID assay were linked to the preprocessed spectra and divided into combined and prediction data sets. Three PLSR calibration models were built: one for the dairy cow colostrum only, the second for beef cow colostrum only, and the third for the merged dairy and beef cow colostrum. The predictive performance of each model was evaluated separately using the independent prediction data set. The Pearson correlation coefficients between IgG concentrations as determined by the TIR-based assay and the RID assay were 0.84 for dairy cow colostrum, 0.88 for beef cow colostrum, and 0.92 for the merged set of dairy and beef cow colostrum. The average of the differences between colostral IgG concentrations obtained by the RID- and TIR-based assays were -3.5, 2.7, and 1.4 g/L for dairy, beef, and merged colostrum samples, respectively. Further, the average relative error of the colostral IgG predicted by the TIR spectroscopy from the RID assay was 5% for dairy cow, 1.2% for beef cow, and 0.8% for the merged data set. The average intra-assay CV% of the IgG concentration predicted by the TIR-based method were 3.2%, 2.5%, and 6.9% for dairy cow, beef cow, and merged data set, respectively.The utility of TIR method for assessment of colostrum quality was evaluated using the entire data set and showed that TIR spectroscopy accurately identified the quality status of 91% of dairy cow colostrum, 95% of beef cow colostrum, and 89% and 93% of the merged dairy and beef cow colostrum samples, respectively. The results showed that TIR spectroscopy demonstrates potential as a simple, rapid, and cost-efficient method for use as an estimate of IgG concentration in dairy and beef cow colostrum samples and assessment of colostrum quality. The results also showed that merging the dairy and beef cow colostrum sample data sets improved the predictive ability of the TIR spectroscopy.

A Case of Type 1 Autoimmune Pancreatitis (AIP), a Form of IgG4-Related Disease (IgG4-RD)

BACKGROUND Type 1 autoimmune pancreatitis (AIP), also known as lymphoplasmacytic sclerosing pancreatitis (LPSP), is a rare cause of chronic pancreatitis, characterized by a fibro-inflammatory process. However, patients with AIP may have a good response to corticosteroid therapy. We describe a Tunisian patient with AIP that was confirmed to be an IgG4-related disease (IgG4-RD). CASE REPORT We describe a case of a 70-year-old man who was admitted to hospital for obstructive jaundice and abdominal pain. Serum liver function tests were abnormal and upper abdominal computed tomography (CT) imaging showed diffuse pancreatic swelling and strictures of the main pancreatic duct without any focal lesion. Pancreatico-biliary magnetic resonance imaging (MRI) showed a thickened rim surrounding the pancreatic duct Serum IgG4 levels were elevated, resulting in a diagnosis of IgG4-related AIP. The patient showed a good clinical, biochemical, and radiological response following steroid therapy in combination with azathioprine. CONCLUSIONS The diagnostic workup of IgG4-RD is complex and usually requires a combination of clinical examination, imaging, and serological analysis. As this case report has demonstrated, IgG4-RD should be considered in patients who present with pancreatitis or AIP, because of the favorable response to steroid therapy, particularly when treatment is initiated early.

Correlation between elevated platelet count and immunoglobulin levels in the early convalescent stage of Kawasaki disease

Kawasaki disease (KD) may be an acute systemic immune-mediated disease which occurs after infection of unknown KD pathogen(s). The aim of this study is to evaluate the changes in platelet count and immunoglobulin (Ig) levels (IgG, IgM, IgA, and IgE) during hospitalization.Forty-three patients with complete KD who received intravenous Ig at 2 g/kg were enrolled in South Korea. The platelet count and Ig levels of the patients were examined twice at presentation and around discharge (mean 6.2 ± 2.4 days apart) and the relationships between platelet level and Ig levels were evaluated.The mean patient age was 31 ± 18 months; 28 patients were male and 15 were female. The values of all parameters measured, with the exception of IgE, were significantly increased at the second examination compared with their values at presentation. These values gradually increased over time after fever onset, over periods ranging from 2 to 16 days. The extent by which platelet levels increased over these 2 time points was correlated with the extents by which IgG (P < .01), IgM (P < .01), and IgA levels (P = .01) increased.Both the platelet count and the Ig (IgG, IgM, and IgA) levels increased with a correlation each other during the early convalescent stage of KD. This finding suggests that all Ig subtypes except IgE and platelets may be involved in the recovery from KD and that the extent of increased parameters may reflect the degree of systemic inflammation in acute KD.

Profiling IgG N-glycans as potential biomarker of chronological and biological ages: A community-based study in a Han Chinese population

As an important post-translation modifying process, glycosylation significantly affects the structure and function of immunoglobulin G (IgG) molecules and is essential in many steps of the inflammatory cascade. Studies have demonstrated the potential of using glycosylation features of IgG as a component of predictive biomarkers for chronological age in several European populations, whereas no study has been reported in Chinese. Herein, we report various patterns of changes in IgG glycosylation associated with age by analyzing IgG glycosylation in 701 community-based Han Chinese (244 males, 457 females; 23-68 years old). Eleven IgG glycans, including FA2B, A2G1, FA2[6]G1, FA2[3]G1, FA2[6]BG1, FA2[3]BG1, A2G2, A2BG2, FA2G2, FA2G2S1, and FA2G2S2, change considerably with age and specific combinations of these glycan features can explain 23.3% to 45.4% of the variance in chronological age in this population. This indicates that these combinations of glycan features provide more predictive information than other single markers of biological age such as telomere length. In addition, the clinical traits such as fasting plasma glucose and aspartate aminotransferase associated with biological age are strongly correlated with the combined glycan features. We conclude that IgG glycosylation appears to correlate with both chronological and biological ages, and thus its possible role in the aging process merits further study.

High Yield Expression of Recombinant Human Proteins with the Transient Transfection of HEK293 Cells in Suspension

The art of producing recombinant proteins with complex post-translational modifications represents a major challenge for studies of structure and function. The rapid establishment and high recovery from transiently-transfected mammalian cell lines addresses this barrier and is an effective means of expressing proteins that are naturally channeled through the ER and Golgi-mediated secretory pathway. Here is one protocol for protein expression using the human HEK293F and HEK293S cell lines transfected with a mammalian expression vector designed for high protein yields. The applicability of this system is demonstrated using three representative glycoproteins that expressed with yields between 95-120 mg of purified protein recovered per liter of culture. These proteins are the human FcγRIIIa and the rat α2-6 sialyltransferase, ST6GalI, both expressed with an N-terminal GFP fusion, as well as the unmodified human immunoglobulin G1 Fc. This robust system utilizes a serum-free medium that is adaptable for expression of isotopically enriched proteins and carbohydrates for structural studies using mass spectrometry and nuclear magnetic resonance spectroscopy. Furthermore, the composition of the N-glycan can be tuned by adding a small molecule to prevent certain glycan modifications in a manner that does not reduce yield.

Pro-inflammatory pattern of IgG1 Fc glycosylation in multiple sclerosis cerebrospinal fluid

BACKGROUND

Immunoglobulin G (IgG) effector functions are regulated by the composition of glycans attached to a conserved N-glycosylation site in the Fc part. Intrathecal production of IgG, especially IgG1, is a hallmark of multiple sclerosis (MS), but nothing is known about IgG Fc glycosylation in MS and in cerebrospinal fluid (CSF) in general.

METHODS

We applied mass spectrometry of tryptic Fc glycopeptides to analyze IgG Fc glycosylation (sialylation, galactosylation, fucosylation, and bisecting N-acetylglucosamine (GlcNAc)) in 48 paired CSF and serum samples from adult patients with MS or a first demyelinating event highly suggestive of MS (designated as MS cases), and from healthy volunteers and patients with other non-inflammatory diseases (control group). p values were adjusted for multiple testing.

RESULTS

Our experiments revealed four main results. First, IgG1 glycosylation patterns were different in CSF vs. serum, in the MS group and even in control donors without intrathecal IgG synthesis. Second, in MS patients vs. controls, IgG1 glycosylation patterns were altered in CSF, but not in serum. Specifically, in CSF from the MS group, bisecting GlcNAc were elevated, and afucosylation and galactosylation were reduced. Elevated bisecting GlcNAc and reduced galactosylation are known to enhance IgG effector functions. Third, hypothesis-free regression analysis revealed that alterations of afucosylation and bisecting GlcNAc in CSF from MS cases peaked 2-3 months after the last relapse. Fourth, CSF IgG1 glycosylation correlated with the degree of intrathecal IgG synthesis and CSF cell count.

CONCLUSIONS

The CNS compartment as well as the inflammatory milieu in MS affect IgG1 Fc glycosylation. In MS, the CSF IgG1 glycosylation has features that enhance Fc effector functions.

Antibody induction therapy for lung transplant recipients

BACKGROUND

Lung transplantation has become a valuable and well-accepted treatment option for most end-stage lung diseases. Lung transplant recipients are at risk of transplanted organ rejection, and life-long immunosuppression is necessary. Clear evidence is essential to identify an optimal, safe and effective immunosuppressive treatment strategy for lung transplant recipients. Consensus has not yet been achieved concerning use of immunosuppressive antibodies against T-cells for induction following lung transplantation.

OBJECTIVES

We aimed to assess the benefits and harms of immunosuppressive T-cell antibody induction with ATG, ALG, IL-2RA, alemtuzumab, or muromonab-CD3 for lung transplant recipients.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 4 March 2013 through contact with the Trials Search Co-ordinator using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that compared immunosuppressive monoclonal and polyclonal T-cell antibody induction for lung transplant recipients. An inclusion criterion was that all participants must have received the same maintenance immunosuppressive therapy within each study.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. We derived risk ratios (RR) for dichotomous data and mean differences (MD) for continuous data with 95% confidence intervals (CI). Methodological risk of bias was assessed using the Cochrane risk of bias tool and trial sequential analyses were undertaken to assess the risk of random errors (play of chance).

MAIN RESULTS

Our review included six RCTs (representing a total of 278 adult lung transplant recipients) that assessed the use of T-cell antibody induction. Evaluation of the included studies found all to be at high risk of bias.We conducted comparisons of polyclonal or monoclonal T-cell antibody induction versus no induction (3 studies, 140 participants); polyclonal T-cell antibody versus no induction (3 studies, 125 participants); interleukin-2 receptor antagonists (IL-2RA) versus no induction (1 study, 25 participants); polyclonal T-cell antibody versus muromonab-CD3 (1 study, 64 participants); and polyclonal T-cell antibody versus IL-2RA (3 studies, 100 participants). Overall we found no significant differences among interventions in terms of mortality, acute rejection, adverse effects, infection, pneumonia, cytomegalovirus infection, bronchiolitis obliterans syndrome, post-transplantation lymphoproliferative disease, or cancer.We found a significant outcome difference in one study that compared antithymocyte globulin versus muromonab-CD3 relating to adverse events (25/34 (74%) versus 12/30 (40%); RR 1.84, 95% CI 1.13 to 2.98). This suggested that antithymocyte globulin increased occurrence of adverse events. However, trial sequential analysis found that the required information size had not been reached, and the cumulative Z-curve did not cross the trial sequential alpha-spending monitoring boundaries.None of the studies reported quality of life or kidney injury. Trial sequential analyses indicated that none of the meta-analyses achieved required information sizes and the cumulative Z-curves did not cross the trial sequential alpha-spending monitoring boundaries, nor reached the area of futility.

AUTHORS' CONCLUSIONS

No clear benefits or harms associated with the use of T-cell antibody induction compared with no induction, or when different types of T-cell antibodies were compared were identified in this review. Few studies were identified that investigated use of antibodies against T-cells for induction after lung transplantation, and numbers of participants and outcomes were also limited. Assessment of the included studies found that all were at high risk of methodological bias.Further RCTs are needed to perform robust assessment of the benefits and harms of T-cell antibody induction for lung transplant recipients. Future studies should be designed and conducted according to methodologies to reduce risks of systematic error (bias) and random error (play of chance).

IgG and IgG4 antibodies in subjects with irritable bowel syndrome: a case control study in the general population

BACKGROUND

Patients with Irritable Bowel Syndrome (IBS) often relate their symptoms to the intake of food and modify their diet. IgE-mediated food allergy is uncommon in IBS, but the role of IgG-mediated food hypersensitivity remains inconclusive. The primary aim of this study was to compare food- and yeast-specific IgG and IgG4 antibodies in subjects with and without IBS.

METHODS

This was a case control study in the general population for which subjects completed questionnaires about abdominal complaints and their intake of common food items. Blood samples were collected, and food- and yeast-specific IgG and IgG4 antibodies were measured. Antibodies were measured in mg/L.

RESULTS

We included 269 subjects with IBS and 277 control subjects. After correction for subject characteristics and diet, there were no significant differences with regard to food- and yeast-specific IgG and IgG4 antibodies between subjects with IBS and controls. Lower values of IgG antibodies against egg (OR 0.99 (0.98 to 1.00), p = 0.002) and beef (OR 0.75 (0.60 to 0.94), p = 0.012) and higher values of IgG antibodies against chicken (OR 1.14 (1.03 to 1.27), p = 0.009) were associated with more severe symptoms.

CONCLUSIONS

Our findings suggest that IgG-and IgG4-mediated food and yeast hypersensitivity in IBS is unlikely. IgG antibodies against food and yeast may reflect the diet.

Revisiting the role of glycosylation in the structure of human IgG Fc

Binding of the Fc domain of Immunoglobulin G (IgG) to Fcγ receptors on leukocytes can initiate a series of signaling events resulting in antibody-dependent cell-mediated cytotoxicity (ADCC) and other important immune responses. Fc domains lacking glycosylation at N297 have greatly diminished Fcγ receptor binding and lack the ability to initiate a robust ADCC response. Earlier structural studies of Fc domains with either full length or truncated N297 glycans led to the proposal that these glycans can stabilize an "open" Fc conformation recognized by Fcγ receptors. We determined the structure of an E. coli expressed, aglycosylated human Fc domain at 3.1 Å resolution and observed significant disorder in the C'E loop, a region critical for Fcγ receptor binding, as well as a decrease in distance between the C(H)2 domains relative to glycosylated Fc structures. However, comparison of the aglycosylated human Fc structure with enzymatically deglycosylated Fc structures revealed large differences in the relative orientations and distances between C(H)2 domains. To provide a better appreciation of the physiologically relevant conformation of the Fc domain in solution, we determined Radii of Gyration (R(g)) by small-angle X-ray scattering (SAXS) and found that the aglycosylated Fc displays a larger R(g) than glycosylated Fc, suggesting a more open C(H)2 orientation under these conditions. Moreover, the R(g) of aglycosylated Fc was reduced by mutations at the C(H)2-C(H)3 interface (E382V/M428I), which confer highly selective binding to FcγRI and novel biological activities.

Neuronal Fc-gamma receptor I mediated excitatory effects of IgG immune complex on rat dorsal root ganglion neurons

Pain often accompanies antigen-specific immune-related disorders though little is known of the underlying neural mechanisms. A common feature among these disorders is the elevated level of antigen-specific immunoglobulin (Ig) G in the serum and the presence of IgG immune complex (IC) in the affected tissue. We hypothesize that IC may directly activate the Fc-gamma receptor type I (FcγRI) expressed in nociceptive dorsal root ganglion (DRG) neurons and increase neuronal excitability thus potentially contributing to pain. Immunofluorescent labeling indicated that FcγRI, but not FcγRIIB or FcγRIII, was expressed in a subpopulation of rat DRG neurons including those expressing nociceptive markers. Calcium imaging revealed that the IC, but neither of the antibody (IgG) or antigen alone, produced an increase in intracellular calcium. This effect was abolished by the removal of the IgG Fc portion in the IC or the application of an anti-FcγRI antibody, suggesting a key role of the FcγRI receptor. Removal of extracellular calcium or depletion of intracellular calcium stores prevented the IC-induced calcium response. In whole-cell current-clamp recordings, IC depolarized the resting membrane potential, decreased the rheobase, and increased the number of action potentials evoked by a depolarizing current at 2× rheobase. In about half of the responsive neurons, IC evoked action potential discharges. These results suggest that a subpopulation of nociceptive neurons expresses functional FcγRI and that the activation of this receptor by IC increases neuronal excitability.

Competitive Adsorption of Three Human Plasma Proteins onto Sulfhydryl-to-sulfonate Gradient Surfaces

Competitive adsorption of three human plasma proteins: albumin (HSA), fibrinogen (Fgn), and immunoglobulin G (IgG) from their ternary solution mixtures onto a sulfhydryl-to-sulfonate gradient surface was investigated using spatially-resolved total internal reflection fluorescence (TIRF) and autoradiography. The concentration of each protein in the ternary solution mixture was kept at an equivalent of 1/100 of its physiological concentration in blood plasma. The three proteins displayed different adsorption and desorption characteristics. Each protein adsorbed less to the sulfonate region than to the sulfhydryl region of the gradient. The adsorption-desorption kinetics revealed large differences in the adsorption and desorption rates of three proteins. By fitting the experimental data to a simple model of competitive protein adsorption, the affinity of each protein to the surface at the gradient center position was ranked as: Fgn > HSA ≫ IgG. Competitive exchange of adsorbed proteins was related to the magnitude of desorption rate constants. Such competitive adsorption of the three major human plasma proteins illustrates the complex dynamics of blood proteins - biomaterials interactions.

Cleavage of IgG1 and IgG3 by gingipain K from Porphyromonas gingivalis may compromise host defense in progressive periodontitis

Degradation of immunoglobulins is an effective strategy of bacteria to evade the immune system. We have tested whether human IgG is a substrate for gingipain K of Porphyromonas gingivalis and found that the enzyme can hydrolyze subclass 1 and 3 of human IgG. The heavy chain of IgG(1) was cleaved at a single site within the hinge region, generating Fab and Fc fragments. IgG(3) was also cleaved within the heavy chain, but at several sites around the CH2 region. Investigation of the enzyme kinetics of IgG proteolysis by gingipain K, using FPLC- and isothermal titration calorimetry-based assays followed by Hill plots, revealed non-Michaelis-Menten kinetics involving a mechanism of positive cooperativity. In ex vivo studies, it was shown that gingipain K retained its IgG hydrolyzing activity in human plasma despite the high content of natural protease inhibitors; that IgG(1) cleavage products were detected in gingival crevicular fluid samples from patients with severe periodontitis; and that gingipain K treatment of serum samples from patients with high antibody titers against P. gingivalis significantly hindered opsonin-dependent phagocytosis of clinical isolates of P. gingivalis by neutrophils. Altogether, these findings underline a biological function of gingipain K as an IgG protease of pathophysiological importance.

Spatial variation of the charge and sulfur oxidation state in a surface gradient affects plasma protein adsorption

A gradient of negative surface charge based on the 1D spatial variation from surface sulfhydryl to mixed sulfhydryl-sulfonate moieties was prepared by the controlled UV oxidation of a 3-mercaptopropylsilane monolayer on fused silica. The adsorption of three human plasma proteins--albumin (HSA), immunoglobulin G (IgG), and fibrinogen (Fgn)--onto such a surface gradient was studied using spatially resolved total internal reflection fluorescence (TIRF) and autoradiography. Adsorption was measured from dilute solutions equivalent to 1/100 (TIRF, autoradiography), 1/500, and 1/1000 (autoradiography) of protein physiological concentrations in plasma. All three proteins adsorbed more to the nonoxidized sulfhydryl region than to the oxidized, mixed sulfhydryl-sulfonate region of the gradient. In the case of HSA, the adsorption contrast along the gradient was largest when the adsorption took place from more dilute protein solutions. Increasing the concentration to 1/100 of the protein plasma concentration eliminated the effect of the gradient on HSA adsorption and, to the lesser extent, on IgG adsorption. In the case of Fgn, the greatest adsorption contrast was observed at the highest concentration used. On the basis of adsorption kinetics, the estimated binding affinity of HSA for the sulfhydryl region was twice the affinity for the mixed sulfhydryl-sulfonate region of the gradient. For IgG and Fgn, the initial adsorption was transport-limited and the initial adsorption rates approached the computed flux of the protein to the surface.

Binding site on human immunoglobulin G for the affinity ligand HWRGWV

Affinity ligand HWRGWV has demonstrated the ability to isolate human immunoglobulin G (hIgG) from mammalian cell culture media. The ligand specifically binds hIgG through its Fc portion. This work shows that deglycosylation of hIgG has no influence on its binding to the HWRGWV ligand and the ligand does not compete with Protein A or Protein G in binding hIgG. It is suggested by the mass spectrometry (MS) data and docking simulation that HWRGWV binds to the pFc portion of hIgG and interacts with the amino acids in the loop Ser383-Asn389 (SNGQPEN) located in the C(H)3 domain. Subsequent modeling has suggested a possible three-dimensional minimized solution structure for the interaction of hIgG and the HWRGWV ligand. The results support the fact that a peptide as small as a hexamer can have specific interactions with large proteins such as hIgG.

Immune and non-immune functions of the (not so) neonatal Fc receptor, FcRn

Careful regulation of the body's immunoglobulin-G (IgG) and albumin concentrations is necessitated by the importance of their respective functions. As such, the neonatal Fc receptor (FcRn) which, as a single receptor, is capable of regulating both of these molecules, has become an important focus of investigation. In addition to these essential protection functions, FcRn possesses a host of other functions that are equally as critical. During the very first stages of life, FcRn mediates the passive transfer of IgG from mother to offspring both before and after birth. In the adult, FcRn regulates the persistence of both IgG and albumin in the serum as well as the movement of IgG, and any bound cargo, between different compartments of the body. This shuttling allows for the movement not only of monomeric ligand but also of antigen/antibody complexes from one cell type to another in such a way as to facilitate the efficient initiation of immune responses towards opsonized pathogens. As such, FcRn continues to play the role of an immunological sensor throughout adult life, particularly in regions such as the gut which are exposed to a large number of infectious antigens. Increasing appreciation for the contributions of FcRn to both homeostatic and pathological states is generating an intense interest in the potential for therapeutic modulation of FcRn binding. A greater understanding of FcRn's pleiotropic roles is thus imperative for a variety of therapeutic purposes.

Crystallization and preliminary X-ray diffraction studies of an RNA aptamer in complex with the human IgG Fc fragment

Aptamers, which are folded DNA or RNA molecules, bind to target molecules with high affinity and specificity. An RNA aptamer specific for the Fc fragment of human immunoglobulin G (IgG) has recently been identified and it has been demonstrated that an optimized 24-nucleotide RNA aptamer binds to the Fc fragment of human IgG and not to other species. In order to clarify the structural basis of the high specificity of the RNA aptamer, it was crystallized in complex with the Fc fragment of human IgG1. Preliminary X-ray diffraction studies revealed that the crystals belonged to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 83.7, b = 107.2, c = 79.0 A. A data set has been collected to 2.2 A resolution.

Neuromyelitis optica in a young child with positive serum autoantibody

Relapsing neuromyelitis optica is rare in children. The identification of a highly specific serum autoantibody marker (neuromyelitis optica-immunoglobulin G) differentiates neuromyelitis optica from other demyelinating disorders, particularly in clinically challenging cases. We present a child with multiple episodes of transverse myelitis and optic neuritis with positive neuromyelitis optica-immunoglobulin G titers, consistent with a diagnosis of relapsing neuromyelitis optica. Serial titers of neuromyelitis optica-immunoglobulin G normalized during remission.

Cerebral infarction in IgG multiple myeloma with hyperviscosity

Cerebral infarction is an uncommon complication in multiple myeloma with hyperviscosity. Serum hyperviscosity may cause a variety of clinical manifestations including bleeding from mucosal membranes, congestive heart failure, retinopathy, and various neurologic deficits. These manifestations have been attributed to the presence of large quantities of asymmetrical molecules of high molecular weight in the serum. We recently experienced a case of multiple myeloma with acute cerebral infarction, which caused by hyperviscosity, as an initial manifestation in IgG multiple myeloma, and reviewed the relevant literature of myeloma presenting with the stroke. A 68-yr-old woman abruptly developed hypesthesia and monoplegia in the left leg. The stroke confirmed by the brain MRI and MR angiography, which revealed acute infarction at the right anterior cerebral artery territory. On admission, routine blood tests showed a slight decrease in hemoglobin and a marked increase in erythrocyte sedimentation rate. Peripheral blood smear, serum protein electrophoresis, serum visocity, and bone marrow aspiration showed that she had IgG multiple myeloma with hyperviscosity. She was treated by chemotherapy with cyclophosphamide and discharged with the improved clinical condition.

Hypogalactosylation of serum IgG in patients with coeliac disease

Coeliac disease (CD) is described as an autoimmune enteropathy associated with the presence of IgG and IgA antigliadin and antitransglutaminase autoantibodies. While of diagnostic significance, the role of these autoantibodies in the immunopathogenesis of CD is elucidated. An inappropriate T cell immune response to gluten is also involved in the pathogenesis of CD, as evidenced by autoantibody switching. The N-glycans released from serum IgG of CD patients and three groups of healthy controls, of differing age ranges, were analysed by NH2-high performance liquid chromatography (HPLC). The fucosylated biantennary N- glycans were the most abundant neutral oligosaccharides; in particular, the agalacto form (G0F) showed a mean value of 42% (s.d. +/- 7.4), 30% (s.d. +/- 5.9), 26% (s.d. +/- 4.2) and 35% (s.d. +/- 6.8) for CD patients, healthy children, healthy adults under 40 and healthy adults over 40 years old, respectively. The ratio of asialo agalacto fucosylated biantenna to asialo monogalacto fucosylated biantenna (G0F)/(G1F) for CD patients showed a significant increase compared to healthy children (P < 0.0002), healthy adults under 40 (P < 0.0002) and healthy adults over 40 years old (P < 0.01). Hypogalactosylation was more pronounced for CD patients than for the patients with other autoimmune diseases such as rheumatoid arthritis or psoriatic arthritis.

Formulation of colostrum supplements, colostrum replacers and acquisition of passive immunity in neonatal calves

Provision of an adequate mass of IgG from maternal colostrum is essential to health and survival of neonatal calves. Colostrum supplements (CS) have been developed to provide supplemental immunoglobulin when maternal colostrum is of poor quality. However, colostrum replacers (CR) that provide > or = 100 g of IgG have not been formulated. Our objective was to determine the absorption of IgG in newborn calves fed CS derived from bovine serum or CR derived from bovine immunoglobulin concentrate. The CS were prepared by collecting, processing, and spray drying bovine serum and blending with other ingredients to provide 45 to 50 g of IgG per dose. The CR were prepared by further processing bovine serum to increase IgG concentration to > 50% IgG and blending with other ingredients to provide 100 to 122 g of IgG per dose. Holstein calves (n = 160) were fed 90 to 244 g of IgG from CS or CR in 1 or 2 feedings in two experiments. Blood was collected from each calf by jugular venipuncture at 0 and 24 h of age and plasma IgG was determined by turbidimetric immunoassay. Apparent efficiency of IgG absorption was calculated. Plasma IgG concentrations at 24 h of age were indicative of IgG intake and averaged 5.5 to 14.1 g/L in calves fed CS and CR. Mean apparent efficiency of IgG absorption in calves fed CS was 25 and 28% in experiments 1 and 2, respectively. Mean apparent efficiency of IgG absorption in calves fed CR ranged from 19 to 32% and were affected by method of processing and number of times fed. Treatment of plasma with polyethylene glycol reduced the efficiency of IgG absorption in experiment 1. The addition of animal fat to CR had no effect on IgG absorption. A second feeding of CR increased plasma IgG, but efficiency of absorption was reduced. Mean body weights at 60 d of age were not affected by treatment and ranged from 64.3 to 78.2 kg. Plasma IgG concentration in calves fed > or = 122 g of IgG from Ig concentrate approached (9.9 g/L) or exceeded 10 g/L, indicating successful transfer of passive immunity. Provision of IgG to prevent failure of passive transfer is possible with CR containing >20% IgG when fed at 454 g per dose.

Preparations of recombinant HIV-1 p66 antigen to improve the specificity of immune complex transfer enzyme immunoassay of antibody IgG to HIV-1 reverse transcriptase

Recombinant HIV-1 p66 (rp66, a subunit of reverse transcriptase (RT), a heterodimer of p66 and p51) was produced in Escherichia coli in three different ways. First, rp66 was produced as a part of the fusion protein of lacZ protein and HIV-1 pol protein consisting of three components: protease (p10), RT (p51/p66), and integrase (p31), and was released from the fusion protein by the protease (pol-rp66). Second, rp66 with Ser-Ser at the N-terminus was produced as a fusion protein with maltose-binding protein containing a factor Xa site between the two proteins (MBP-Ser-Ser-rp66) and was released from the fusion protein by factor Xa (Ser-Ser-rp66). Third, rp66 with Met-Gly at the N-terminus was produced in transformed cells (Met-Gly-rp66). The recombinant proteins were purified from sonic extracts of transformed cells by ammonium sulfate fractionation and various column chromatographies. MBP-Ser-Ser-rp66 and Met-Gly-rp66 were readily purified in sufficient amounts for labeling with 2, 4-dinitrophenyl groups and beta-D-galactosidase from E. coli, but pol-rp66 and Ser-Ser-rp66 were not for enzyme-labeling. Ser-Ser-rp66 was not only polymerized but also degraded to considerable extents. The purified preparations were labeled with 2,4-dinitrophenyl groups and beta-D-galactosidase and were tested in immune complex transfer enzyme immunoassay of antibody IgG to HIV-1 RT using serum samples from 600 HIV-1 seronegative and 30 HIV-1 seropositive subjects. Among various combined uses of the two labeled preparations, the uses of 2,4-dinitrophenylated MBP-Ser-Ser-rp66 and pol-rp66 with beta-D-galactosidase-labeled Met-Gly-rp66 showed the highest (99.8%) and the second highest (99.5%) specificities, which were higher than that with the labeled preparations used in the previous study (98. 0%).

The major receptor for C-reactive protein on leukocytes is fcgamma receptor II

C-reactive protein (CRP) is an acute phase serum protein that shares several functions with immunoglobulin (Ig)G including complement activation and binding to receptors on monocytes and neutrophils. The identity of the receptor for CRP has been the target of extensive research. We previously determined that CRP binds to the high affinity receptor for IgG, FcgammaRI (CD64). However, this interaction could not account for the majority of binding of CRP to neutrophils or monocytic cells. We now determine that CRP also interacts with FcgammaRIIa (CD32), the low affinity receptor for IgG on monocytes and neutrophils. COS-7 cells were transfected with a construct containing the human FcgammaRIIA cDNA. CRP binding and the presence of CD32 were detected by mAb and analyzed by two-color flow cytometry. Cells expressing CD32 bound CRP in a dose-dependent and saturable manner consistent with receptor binding. CRP bound to transfectants and K-562 cells with similar kinetics, and in both cases binding was completely inhibited by aggregated IgG. On monocytic cell lines, treatment with Bt(2)cAMP increased FcgammaRII expression and enhanced CRP binding. CRP also specifically precipitated FcgammaRI and FcgammaRII from the monocytic cell line, THP-1. It is suggested that the major receptor for CRP on phagocytic cells is FcgammaRII.

BAFF, a novel ligand of the tumor necrosis factor family, stimulates B cell growth

Members of the tumor necrosis factor (TNF) family induce pleiotropic biological responses, including cell growth, differentiation, and even death. Here we describe a novel member of the TNF family, designated BAFF (for B cell activating factor belonging to the TNF family), which is expressed by T cells and dendritic cells. Human BAFF was mapped to chromosome 13q32-34. Membrane-bound BAFF was processed and secreted through the action of a protease whose specificity matches that of the furin family of proprotein convertases. The expression of BAFF receptor appeared to be restricted to B cells. Both membrane-bound and soluble BAFF induced proliferation of anti-immunoglobulin M-stimulated peripheral blood B lymphocytes. Moreover, increased amounts of immunoglobulins were found in supernatants of germinal center-like B cells costimulated with BAFF. These results suggest that BAFF plays an important role as costimulator of B cell proliferation and function.

The relationship between exposed galactose and N-acetylglucosamine residues on IgG in rheumatoid arthritis (RA), juvenile chronic arthritis (JCA) and Sjögren's syndrome (SS)

The relationship between exposed galactose and N-acetylglucosamine on IgG in RA, JCA and SS was investigated. This was achieved using IgG isolated from serum where the levels of galactose and N-acetylglucosamine (GlcNAc) were detected using biotinylated lectins. Galactose and GlcNAc on IgG from patients with RA and JCA are inversely related, but in contrast, in SS, galactose expression on IgG decreased while GlcNAc expression remained similar to normal levels. Alterations in IgG glycosylation are closely associated with the development of adult and juvenile chronic arthritis and SS, but the changes involved are different in RA compared with SS, suggesting that the precise pattern of exposed sugars is associated with different rheumatological diseases.

Cascade chromatography and automated multidimensional fractionation

A general method of automated multidimensional fractionation has been developed. Its basic ingredients are: (a) cascade fractionation, i.e., the sequential fractionation of components obtained from each chromatographic dimension on the same or a different dimension, (b) on-line acquisition and processing of data at each stage in the fractionation procedure, (c) a method for determining the beginning and end of each peak during column elution, and (d) automatic linkage of the successive stages in a chemical fractionation scheme based on information obtained before or during each stage. Apparatus for automatic cascade chromatography and conditional fractionation is described. The method can be extended to provide completely automatic separation of pure components from complex mixtures.