Ultrasound-guided aspiration and corticosteroid injection compared to horizontal therapy for treatment of knee osteoarthritis complicated with Baker's cyst: a randomized, controlled trial

BACKGROUND

Combining different therapies, physical therapy agents, pharmacological and physical therapies, generally produces better outcomes for symptoms of knee osteoarthritis (OA) than do isolated therapies.

AIM

To demonstrate if horizontal therapy (HT) and aspiration alone and corticosteroid injection alone or in combination determine pain relief and functional improvement in a group of patients with knee OA complicated with Baker's cyst (BC).

DESIGN

We designed a randomized controlled trial (RCT).

SETTING

Outpatients.

POPULATION

Sixty patients with a knee OA and diagnosis of BC confirmed by means of standard ultrasound (US) evaluation.

METHODS

The trial was conducted as a randomized, controlled trial. Patients who satisfied the inclusion criteria were randomized to either the US-guided (Ultrasound Guided BC aspiration and corticosteroid injection group (Group A), the Horizontal Therapy group (Group B) or the US-guided BC aspiration and corticosteroid injection plus Horizontal therapy group (Group C). Outcome measures included: 1) pain reduction as measured by visual analogue scale (VAS); 2) functional improvement, as measured by WOMAC; and 3) US evaluation at baseline (T0), at one (T1) and four (T2) weeks follow-up.

RESULTS

A total of 60 patients were randomized into group A (N.=20), group B (N.=20) or Group C (N.=20). Patients in group A and in group C, but not those in group B maintained lower pain level at T2 than at baseline, with significant lower VAS values in Group C. As regards US measurements, the maximum axial area did not change as a consequence of the treatment in any of the three groups (P=0.259). Contrarily, sagittal area measurements were influenced by time (P<0.01).

CONCLUSION

Our results show that the group with the best performance for pain, functionality and dimension of BC was that in which combined use was made of horizontal and corticosteroid injection therapies.

CLINICAL REHABILITATION IMPACT

In this study we want to demonstrate the effectiveness of Horizontal Therapy in the treatment of knee OA complicated by BC.

Hypervariable region 1 of hepatitis C virus: immunological decoy or biologically relevant domain?

The hypervariable region 1 (HVR1) of the E2 protein of hepatitis C virus (HCV) is highly heterogeneous and is responsible for significant inter- and intra-individual variation of the infecting virus, which may represent an important pathogenetic mechanism leading to escape and persistent infection. Moreover, a binding site for neutralizing antibodies (Ab) has been allegedly identified in this region. Prospective studies of serological responses to synthetic oligopeptides derived from HVR1 sequences of patients with acute and chronic HCV infection showed extensive serological cross-reactivity for unrelated HVR1 peptides in the majority of the patients. A significant correlation was found between HVR1 sequence variation, and intensity, and cross-reactivity of humoral immune responses providing strong evidence in support of the contention that HCV variant selection is driven by the host immune pressure. Monoclonal Ab (mAb) generated following immunization of mice with peptides derived from natural HVR1 sequences also showed cross-reactivity for several HVR1 sequences attesting to the existence of conserved amino acid motifs among different variants. These findings suggest that it is possible to induce a broadly cross-reactive immune response to HVR1 and that this mechanism can be used to generate protective immunity for a large repertoire of HCV variants.

Monoclonal antibodies with broad specificity for hepatitis C virus hypervariable region 1 variants can recognize viral particles

The hypervariable region 1 (HVR1) of the E2 protein of hepatitis C virus (HCV) is a highly heterogeneous sequence that is promiscuously recognized by human sera via binding to amino acid residues with conserved physicochemical properties. We generated a panel of mAbs from mice immunized with HVR1 surrogate peptides (mimotopes) affinity-selected with sera from HCV-infected patients from a phage display library. A high number of specific clones was obtained after immunization with a pool of nine mimotopes, and the resulting mAbs were shown to recognize several 16- and 27-mer peptides derived from natural HVR1 sequences isolated from patients with acute and chronic HCV infection, suggesting that HVR1 mimotopes were efficient antigenic and immunogenic mimics of naturally occurring HCV variants. Moreover, most mAbs were shown to bind HVR1 in the context of a complete soluble form of the E2 glycoprotein, indicating recognition of correctly folded HVR1. In addition, a highly promiscuous mAb was able to specifically capture bona fide viral particles (circulating HCV RNA) as well as rHCV-like particles assembled in insect cells expressing structural viral polypeptides derived from an HCV 1a isolate. These findings demonstrate that it is possible to induce a broadly cross-reactive clonal Ab response to multiple HCV variants. In consideration of the potentially important role of HVR1 in virus binding to cellular receptor(s), such a mechanism could be exploited for induction of neutralizing Abs specific for a large repertoire of viral variants.

Antibody responses to hepatitis C virus hypervariable region 1: evidence for cross-reactivity and immune-mediated sequence variation

Sequence heterogeneity of hepatitis C virus (HCV) is unevenly distributed along the genome, and maximal variation is confined to a short sequence of the HCV second envelope glycoprotein (E2), designated hypervariable region 1 (HVR1), whose biological function is still undefined. We prospectively studied serological responses to synthetic oligopeptides derived from HVR1 sequences of patients with acute and chronic HCV infection obtained at baseline and after a defined follow-up period. Extensive serological cross-reactivity for unrelated HVR1 peptides was observed in the majority of the patients. Antibody response was restricted to the IgG1 isotype and was focused on the carboxyterminal end of the HVR1 region. Cross-reactive antibodies could be readily elicited following immunization of mice with multiple antigenic peptides carrying HVR1 sequences derived from our patients. The vigor and heterogeneity of cross-reactive antibody responses were significantly higher in patients with chronic hepatitis compared with those with acute hepatitis and in patients infected with HCV type 2 compared with patients infected with other viral genotypes (predominantly type 1), which suggest that higher time-related HVR1 sequence diversification previously described for type 2 may result from immune selection. The finding of a statistically significant correlation between HVR1 sequence variation, and intensity, and cross-reactivity of humoral immune responses provided stronger evidence in support of the contention that HCV variant selection is driven by the host's immune pressure.

GB virus type C infection in patients treated for childhood acute lymphoblastic leukemia

BACKGROUND

The purpose of this study was to determine the prevalence of GB virus type C (GBV-C) infection in subjects treated for childhood acute lymphoblastic leukemia (ALL) or non-Hodgkin's lymphoma.

STUDY DESIGN AND METHODS

One hundred forty patients (82 males) aged 4 to 27 years (median, 11) diagnosed with ALL between 1976 and 1993, were prospectively followed for a median of 5 years (range, 0.1-17) after completion of therapy. Stored sera were tested for antibody to hepatitis C virus (HCV), HCV RNA, antibody to GBV-C E2 (anti-E2), and GBV-C RNA.

RESULTS

Thirty-eight patients (27%) were exposed to GBV-C: 30 were positive for GBV-C RNA (mostly type 2) and 8 were positive for anti-E2. Anti-E2 and GBV-C RNA were mutually exclusive: 61 patients (43%) were positive for HCV RNA, 16 (11%) were coinfected with GBV-C and HCV. Alanine aminotransferase (ALT) levels were increased (>35 mU/mL) in 32 (23%) of 137: 3 of 20 who were positive for GBV-C and negative for HCV, 7 of 15 who were positive for GBV-C and HCV, 15 of 44 who were negative for GBV-C and positive for HCV, and 7 of 58 who were negative for GBV-C and HCV (p<0.001). Median ALT values were significantly higher in patients positive for GBV-C and HCV than in those who were positive for GBV-C and negative for HCV (35 vs. 13 mU/mL, p = 0.003). Thirty-one of 38 patients with GBV-C markers were retested: GBV-C RNA was lost in 16 of 30 tested, but 7 were still GBV-C RNA positive up to 50 months later, 3 tested positive for anti-E2 up to 27 months later, and 1 was positive for GBV-C RNA and anti-E2 26 months later, while 20 tested negative for both.

CONCLUSION

GBV-C did not behave as a liver pathogen, because ALT alterations were unrelated to GBV-C status, but, rather, were related to HCV infection or coinfection. GBV-C RNA was frequently lost over a relatively short period, though in some cases, it was retained for a longer time. Anti-E2 rarely coexisted with GBV-C RNA and might be short-term.

Production of human monoclonal antibodies to hepatitis C virus and their characterization

Human monoclonal antibodies (hMAb) provide novel ways to probe the B-cell repertoire in health and disease. However, the development of hMAb technology has met with several difficulties owing to the instability of the cell lines, the low level of specific antibody secretion, and the poor cloning efficiency, particularly when using lymphoblastoid cells (1,2). In order to overcome these problems, some investigators have fused human B lymphocytes with human/mouse myeloma heterohybrids. However, in such systems, human chromosomes are unstable and may occasionally be deleted. Despite the potential emergence of technical pitfalls, B-cell immortalization with EBV has been extensively used for hMAb production, because of its simplicity and because EBV can bind to and penetrate in virtually all B lymphocytes, theoretically allowing the exploration of the whole B-cell repertoire. The most recent protocols have made use of techniques aimed at expanding the population of antigen-specific B-cell precursors and improving the capacity of B-cells to grow at low density. These methods will be discussed below.

Clonality and specificity of cryoglobulins associated with HCV: pathophysiological implications

BACKGROUND/AIMS

Hepatitis C virus (HCV) infection plays a central role in the pathogenesis of mixed cryoglobulinemia through molecular mechanisms which remain to be elucidated. The aim of this study was to investigate the role of antibody responses to HCV in the pathogenesis of cryoglobulinemia through characterization of the anti-HCV specificity and immunochemical characteristics of the immunoglobulins involved in cryoprecipitation.

METHODS

Sera from 50 consecutive patients with chronic HCV infection (RNA positive) were screened for the presence of cryoglobulins. The two major components of cryoprecipitates, IgM rheumatoid factors and IgG, were separated by high performance liquid chromatography and analyzed for immunochemical composition by immunoblotting and antibody specificity by ELISA and immunoblotting using recombinant HCV proteins and synthetic peptides as antigens.

RESULTS

Cryoprecipitates were observed in 27 patients and characterized by immunofixation: 13 (48%) were classified as type II and 14 (52%) as type III. Monoclonal immunoglobulins were detected by immunoblotting in 20 cryoprecipitates: IgM in 14 samples and IgG in 14, with a clear preponderance of IgG3 (12/14). Specificity studies on sera and purified IgM and IgG fractions from cryoprecipitates revealed enrichment in cryoglobulins, predominantly polyclonal IgG1, reactive with the HCV structural proteins, whereas specificities for nonstructural viral proteins were relatively less represented compared to whole serum. No restricted pattern of fine specificity was observed. IgG3 subclass was apparently not involved in HCV nucleoprotein binding.

CONCLUSIONS

Our findings do not support a direct link between monoclonal cryoglobulins and immune response to HCV According to the proposed pathogenetic model, HCV infection can induce the formation of cryoprecipitable rheumatoid factors, sustain their production, and eventually lead to monoclonal B-cell expansion through several cooperative mechanisms.

HGV/GBV-C infection in liver transplant recipients: antibodies to the viral E2 envelope glycoprotein protect from de novo infection

BACKGROUND/AIMS

Liver transplantation for endstage liver cirrhosis provides a useful model to investigate the pathogenetic role of hepatotropic viral agents. Recently, a new member of the Flaviviridae family, provisionally named HGV/GBV-C virus, has been associated with acute and chronic non A-E hepatitis. We studied 136 patients with cirrhosis consecutively transplanted at our institution for evidence of hepatitis G virus infection and correlation with the patients' clinical course.

METHODS

All patients survived for at least 6 months after transplantation (median follow-up 44 months) and underwent routine liver biopsies. Hepatitis G virus infection was studied using both direct viral RNA identification by RT-PCR and indirect detection of antibodies to the E2 glycoprotein.

RESULTS

There was a high frequency of the hepatitis G virus among patients undergoing liver transplantation, with HGV RNA and anti-E2 prevalence rates of 18.4% and 26.5%, respectively. HGV RNA prevalences significantly increased after transplantation (47.8%), with 47.3% rate of new infections in susceptible subjects. Anti-E2 antibodies were significantly more prevalent among patients transplanted for HCV-related cirrhosis and represented a strong protective factor against hepatitis G virus reinfection or recurrent infection. No correlation was found between HGV RNA or anti-E2 prevalences and survival after transplantation or rates of recurrent liver damage.

CONCLUSIONS

All available evidence suggests that, although liver transplant patients are heavily exposed to hepatitis G virus both before and after transplantation, hepatitis G virus does not induce liver disease in this setting. Most infections appear to be self-limited and induce a protective immunity which is marked by the presence of anti-E2 antibodies.

Antibody-negative chronic hepatitis C virus infection in immunocompetent children

Antibody-negative hepatitis C virus (HCV) infection, defined by the presence of HCV viremia in the absence of a serologic response to HCV, was detected in two immunocompetent and symptom-free children; each had a history of exposure to blood products. HCV infection may occasionally explain cryptogenic elevation of aminotransferases, even in the absence of serum anti-HCV. HCV-RNA should be investigated in these cases, particularly in the presence of previous exposure to blood products.

Recombinant human antibodies specific for hepatitis C virus proteins

Human antibodies to hepatitis C virus core, NS4A and NS3 were cloned in a prokaryotic vector and expressed as soluble Fab fragments and as phage-displayed Fabs. The recombinant Fabs were shown to be a suitable tool for immunohistochemistry, since they recognize the cognate antigen expressed in mammalian cells. The nucleotide sequence of the cDNA for the variable domains of these antibodies was determined and the V-gene usage was derived. On the basis of the deduced amino acid sequence, a structural model of the V domains of the Fabs was constructed.

Hepatitis C virus infection among institutionalised psychiatric patients: a regression analysis of indicators of risk

BACKGROUND/AIMS

Institutionalised psychiatric patients are at increased risk of developing chronic infection with hepatitis B virus (HBV). However, little information is available on transmission and epidemiology of hepatitis C virus (HCV) in this setting. The aim of this study was to identify potential risk factors of acquiring HCV infection in two large psychiatric institutions in northern Italy.

METHODS

We designed a case-control study using randomly selected controls from the same study database, consisting of a total of 1180 patients, in order to satisfy the principle that both cases and controls should be representative of the same base experience. A multiple regression logistic analysis was used to identify features that could predict exposure to HCV as evidenced by the presence of circulating anti-HCV antibodies.

RESULTS

Anti-HCV was detected in 79 patients (6.7%). The prevalence of viraemia and the distribution of genotypes were very similar to those found in subjects with chronic HCV infection drawn from the same geographical area. Multivariate analysis indicated that a diagnosis of psychosis and a history of trauma were statistically significant independent risk factors associated with a positive anti-HCV result (OR 2.615, 1.273-5.373 95% CI and OR 2.096, 1.133-3.877 95% CI, respectively).

CONCLUSIONS

The findings of this large epidemiological study show for the first time that prolonged residence in psychiatric institutions does not entail per se a significant risk of acquiring HCV infection. Since transmission of HCV in this setting appears to occur predominantly via classical parenteral routes, simple prophylactic measures appear to be adequate to prevent infection.

Antibody responses to the hepatitis C virus E2 protein: relationship to viraemia and prevalence in anti-HCV seronegative subjects

A small proportion of patients with chronic hepatitis C virus (HCV) infection show no serological responses to the HCV polypeptides incorporated in commercial III generation immunoassays. To determine whether sera from these subjects contain antibodies to the highly immunoreactive second envelope polypeptide E2, which is not included in current anti-HCV assays, we studied 59 anti-HCV negative subjects who were found consistently to be HCV RNA positive by polymerase chain reaction (PCR). Controls included 167 anti-HCV seropositive patients with or without serum HCV RNA and normal subjects. Antibodies to the E2 region were sought for by ELISA using the following antigens: a full length E2 protein expressed in insect cells using a baculovirus vector and extracted under denaturing conditions (dE2), and a C-terminal truncated soluble E2 (sE2) protein (a.a. 390-683), also expressed with a baculovirus vector, containing a signal peptide of rabies virus G protein which allows its secretion into the culture supernatant. Sera from only two (3.4%) of the 59 anti-HCV negative, HCV RNA positive patients recognised sE2 and none dE2. In sharp contrast, 82% of seropositive, viraemic patients recognised sE2 and 60% dE2, the difference in immunoreactivity being statistically significant (P < 0.0003). A significantly lower proportion of sera from anti-HCV positive, HCV RNA negative subjects recognised either sE2 or dE2 (16% and 13%, respectively, P < 0.000001). Healthy controls were consistently negative. These results indicate that antibody responses to predominantly conformational epitopes on the HCV E2 protein are common in patients with chronic HCV infection and are strictly related to the presence of circulating viral genomes. In contrast, only a minor proportion of HCV RNA positive patients, but anti-HCV seronegative by commercial immunoassays, have humoral immune responses to the HCV E2 region.

Hepatitis C virus genotypes and risk of hepatocellular carcinoma in cirrhosis: a prospective study

A prospective study was performed to establish whether infection with specific hepatitis C virus (HCV) genotypes was associated with an increased risk of development of hepatocellular carcinoma (HCC) in cirrhosis. A cohort of 163 consecutive hepatitis C virus antibody (anti-HCV)-positive cirrhotic patients was prospectively evaluated for the development of HCC at 6-month intervals by ultrasound (US) scan and alpha-fetoprotein (AFP) concentration. HCV genotypes were determined according to Okamoto. Risk factors associated with cancer development were analyzed by univariate and multivariate statistics. At enrollment, 101 patients (62%) were infected with type 1b, 48 (29.5%) were infected with type 2a/c, 2 (1.2%) were infected with type 3a, 1 (0.6%) was infected with type 1a, 3 (1.8%) had a mixed-type infection, and, in 8 patients (4.9%), genotype could not be assigned. After a 5- to 7-year follow-up (median, 68 months), HCC developed in 22 of the patients, 19 infected with type 1b and 3 with type 2a/c (P < .005). Moreover, HCC developed more frequently in males (P < .01), patients with excessive alcohol intake (P < .01), those over 60 years of age (P < .02), and in patients who did not receive interferon treatment (P < .02). Multivariate analysis showed that type 1b was the most important risk factor associated with tumor development (odds ratio 6.14, 1.77-21.37 95% confidence interval). Other independent risk factors were older age and male sex. Cirrhotic patients infected with HCV type 1b carry a significantly higher risk of developing HCC than patients infected by other HCV types. The latter may require a less intensive clinical surveillance for the early detection of neoplasia.

Comparative evaluation of two serologic typing methods for hepatitis C virus

Serologic methods of typing for hepatitis C virus offer advantages over PCR-based typing methods in terms of speed and simplicity of sample preparation and in the use of standard laboratory equipment. We examined the sensitivities and specificities of two hepatitis C virus serotyping assays which use sets of type-specific antigenic peptides derived from the core or the nonstructural 4 (NS4) regions and compared the results with those of molecular typing with type-specific primers from the core region. Although there was a good concordance between serotyping by either assay and genotyping, we found that the sensitivities of both serologic assays were less than optimal compared with that of molecular typing, with only about 50% of samples being unequivocally typed. Moreover, amino acid sequence similarities within the regions of the genome used for serotyping preclude differentiation into subtypes, which may have important clinical and therapeutic implications.

A human antibody specific for hepatitis C virus core protein: synthesis in a bacterial system and characterization

The cDNA coding for the Fab fragment of the human B12.F8 antibody (Ab), directed against the putative nucleocapsid component (core protein) of hepatitis C virus (HCV), was cloned in the prokaryotic phagemid vector, pHEN-1, to obtain its expression in Escherichia coli. The functionality and specificity of the recombinant Ab, called B12Fab, were examined by Western blot and ELISA using recombinant HCV core protein as antigen. The specificity of B12Fab was further confirmed by ELISA with the 33-mer peptide epitope recognized by the original whole B12.F8 Ab. By immunofluorescence, the recombinant B12Fab was shown to recognize HCV core protein produced in cells transfected with HCV cDNA, indicating that the recombinant B12Fab is suitable as a diagnostic tool for tissue localization of the virus. The B12Fab also functioned when displayed on phage particles, providing the basis for future experiments of in vitro affinity maturation and selection of mutants. The variable chain coding regions of the recombinant B12Fab clone were sequenced and the V-gene usage was determined by comparison with the V kappa and VH germline sequences. The B12Fab V kappa chain belongs to the subgroup II and shows the highest degree of homology with the A3 germline gene, whereas the sequence of the VH chain is strictly related to that of the Humhv3019b18 gene of the VH3 family. These results are, to our knowledge, the first report of molecular cloning and characterization of a functional human Ab specific for an HCV antigen.

Occurrence of antibodies reactive with more than one variant of the putative envelope glycoprotein (gp70) hypervariable region 1 in viremic hepatitis C virus-infected patients

The hepatitis C virus (HCV) is a frequent cause of chronic liver disease. A mechanism proposed as being responsible for virus persistence is evasion of the host immune response through a high mutation rate in crucial regions of the viral genome. We have sequenced the hypervariable region 1 (HVR1) of the virus isolated from three serum samples, collected during 18 months of follow-up, from an asymptomatic HCV-infected patient. A synthetic peptide of 27 amino acids, corresponding to the HVR1 sequence found to be predominant in both the second and third samples, was used as the antigen for detection of antibodies by enzyme-linked immunosorbent assay (ELISA). We observed reactivity against this HVR1 sequence in the first serum sample before the appearance of the viral isolate in the bloodstream; the reactivity increased in the second and third samples while the cognate viral sequence became predominant. Moreover, our results show that antibodies from all three samples recognize a region mapping at the carboxyl-terminal part of the HVR1 and are cross-reactive with the HVR1 sequence previously found in the same patient. The presence of anti-HVR1 antibodies was investigated in a further 142 HCV patients: 121 viremic and 21 nonviremic. Two synthetic peptides were used, the first corresponding to the sequence derived from the patient described above and the second one synthesized according to the sequence of the HCV BK strain. A high frequency of positive reactions against both HVR1 variants was detected in the samples from the viremic individuals. Finally, antibodies cross-reactive with both variants were shown to be present by competitive ELISA in 6 of 10 viremic patients. The potential negative implications of this observation for the host are discussed.

Molecular epidemiology of hepatitis C virus infection among intravenous drug users

BACKGROUND/AIMS

The clinico-pathological features of hepatitis C virus infection in intravenous drug users are different from those found in other hepatitis C virus-infected patients. Our aim was to test whether specific viral variants circulate within this particular patient population.

METHODS

We studied the distribution of hepatitis C virus genotypes in 90 drug addicts and 484 controls, according to the method described by Okamoto.

RESULTS

Hepatitis C virus type 1a and 3a infections were more frequent among intravenous drug users than in 125 age-matched controls (48.8% and 21.1% vs 17.6% and 11.2%), accounting for the majority of infections in intravenous drug users. Analysis of hepatitis C virus genotypes according to age showed that, in the general population, hepatitis C virus types 1a and 3a were more prevalent among patients younger than 40 years of age than in older individuals (17.6% and 11.2% vs 1.4% and 0.6%).

CONCLUSIONS

These findings suggest that hepatitis C virus types 1a and 3a were recently introduced in Italy, presumably via needle-sharing among intravenous drug users, and from this reservoir they are extending to the general population, particularly among younger subjects.

Differential distribution of hepatitis C virus genotypes in patients with and without liver function abnormalities

Hepatitis C virus (HCV) infection persists for an indefinite length of time in a major proportion of patients, inducing chronic liver lesions that evolve to cirrhosis and hepatocellular carcinoma (HCC) in approximately 20% of cases. We studied HCV viremia and genotypes by reverse transcription-polymerase chain reaction (RT-PCR) in 341 consecutive anti-HCV-positive patients. Of these, 167 patients had persistently normal or near normal alanine aminotransferase (ALT) levels (fluctuations < or = 5 IU above the upper limit of normal); the remaining 174 patients presented with elevated ALT and histological evidence of chronic liver disease. Seventy percent of patients with normal ALT values had circulating HCV RNA despite the absence of biochemical indicators of liver damage and mild histological forms of chronic hepatitis were detected in most patients who underwent liver biopsy. Isolated genotype III infection was significantly more prevalent in this patient group with respect to control patients with abnormal ALT values (70% vs. 39%; P < .001). Conversely, isolated genotype II was more frequently found in patients with elevated ALT values and evidence of chronic liver disease (45% vs. 23%; P < .01) and it was progressively more represented in advanced liver disease, such as cirrhosis and HCC. Virological features of HCV infection might be associated with different clinical manifestations, suggesting a potential prognostic significance on disease outcome.

Hepatitis C virus infection in children treated for acute lymphoblastic leukemia

We studied 102 consecutive subjects after their completion of acute lymphoblastic leukemia (ALL)-directed chemotherapy, for evidence of hepatitis C virus (HCV) infection by enzyme immunoassay 2 and 3, second generation recombinant immunoblot assay and reverse transcription-polymerase chain reaction (PCR) for detection of circulating HCV-RNA. Forty-four patients (43%) had evidence of exposure to HCV; 30 of these were anti-HCV+. Of the 23 patients who were positive for both anti-HCV and HCV-RNA, 16 (69%) had a moderate increase in serum alanine aminotransferase (ALT) activity without clinical signs of liver disease. Fourteen patients were seronegative despite the presence of HCV-RNA in the serum. The proportion of different HCV genotypes was not significantly different from other anti-HCV+ patient groups. Although half of the patients with genotype III had normal ALT value, patients with normal ALT levels were represented in all genotype groups. Our study documents the prevalence of HCV infection in childhood ALL survivors, which is responsible for the majority of cases of non-B chronic liver disease in these patients. Whereas serologic screening identifies over 70% of patients with ongoing HCV infection, real HCV infection may be present even in the absence of a detectable humoral immune response to the virus. Based on this observation, determination of HCV-RNA by PCR should be recommended in patients in prolonged remission even if they test negative on serological assay. Normal ALT levels do not exclude the presence of HCV infection because the values were repeatedly normal in over half of our viremic patients.

Hepatitis C virus (HCV) core serotypes in chronic HCV infection

Recently, two distinct hepatitis C virus (HCV) serologic types have been identified on the basis of amino acid variations in the core region. The two serologic types can readily discriminate between genotypes I-II-V (serotype 1) and III-IV (serotype 2), according to the Okamoto classification. We compared HCV core serotyping with genotyping with sera from 363 anti-HCV-positive patients (309 HCV RNA positive by PCR) using a synthetic core peptide-based enzyme immunoassay and PCR amplification of core region sequences with type-specific primers, respectively. Serologic responses to HCV serotypes were successfully identified in 164 (45%) patients, of whom 153 were viremic. Eighty-nine patients had evidence of exposure to serotype 1: 8 of these were infected with genotype I, 50 were infected with genotype II, 2 were infected with genotype III, 7 were infected with genotype V, 13 had infections with mixed genotypes, 3 were infected with an indeterminate genotype, and 6 were nonviremic. Seventy-four patients had been exposed to serotype 2: 64 were infected with genotype III, 3 were infected with mixed genotypes, 2 were infected with an indeterminate genotype, and 5 were nonviremic. The serum of one patient, infected with genotype III, showed reactivity to both serotypes. Comparative evaluation of HCV core region serotyping and genotyping with sera from 294 viremic patients infected with a known HCV genotype showed a remarkable concordance between HCV core region genotyping and serotyping, with only 2 apparently discordant serum samples (both from patients with genotype III infection) of 148 (1.4%) successfully serotyped samples. Serotype 1 infection was more frequently observed in patients with overt chronic liver disease and accounted for all successfully serotyped samples from intravenous drug abusers. In contrast, serotype 2 was more prevalent in subjects with biochemically silent HCV infection (alanine aminotransferase, < 45 U/liter), in agreement with previous findings at the molecular level. HCV core serologic typing is a simple, inexpensive, and highly reproducible assay that can be applied to more than 50% of viremic HCV antibody carriers prior to the use of more sophisticated molecular typing techniques. Moreover, it may be helpful in tracking transmissions routes, particularly for incorrectly stored samples in which the RNA has degraded or for subjects who have cleared the virus and therefore have only antibodies remaining to testify to a remote infection. The lack of recognition of the core sequence from residues 67 to 81, which contains a minor B-cell epitope used to detect type-specific immunoreactivity, may explain the negative serologic findings for half of the patients.

Significance of the immune response to a major, conformational B-cell epitope on the hepatitis C virus NS3 region defined by a human monoclonal antibody

The nonstructural protein NS3 of hepatitis C virus (HCV) possesses two enzymatic domains which are thought to be essential for the virus life cycle: an N-terminal serine-type proteinase, responsible for the processing of nonstructural polypeptides, and a C-terminal nucleoside triphosphatase/helicase, presumably involved in the unwinding of the viral genome. The human antibody response to NS3 usually appears early in the course of HCV infection and is predominantly directed against the carboxyl-terminal portion; however, its fine specificity and clinical significance are largely unknown. We have generated a human monoclonal antibody (hMAb), designated CM3.B6, from a cloned B-cell line obtained from the peripheral blood of a patient with chronic HCV infection, which selectively recognized the purified NS3 protein expressed in bacteria or in eukaryotic cells transfected with full-length or NS3 cDNA. Fine-specificity studies revealed that CM3.B6 recognized a 92-amino-acid sequence (clone 8, amino acids 1363 to 1454) selected from an NS3 DNase fragment library but failed to bind to 12-mer peptides synthesized from the same region, suggesting recognition of a conformational B-cell epitope. Experiments using deletion mutants of clone 8 and competitive inhibition studies using a panel of NS3 peptide-specific murine MAbs indicated that limited N-terminal and C-terminal deletions resulted in a significant reduction of hMAb binding to clone 8, thus identifying a minimal antibody binding domain within clone 8. Competition experiments showed that binding of CM3.B6 to the NS3 protein was efficiently inhibited by 39 of 44 (89%) sera from HCV-infected patients, suggesting that the hMAb recognized an immunodominant epitope within the NS3 region. More importantly, recognition of the sequence defined by CM3.B6 appeared to accurately discriminate between viremic and nonviremic anti-HCV positive sera, suggesting potentially relevant clinical applications in the diagnosis and treatment of HCV infection.

A human monoclonal antibody specific for the N terminus of the hepatitis C virus nucleocapsid protein

PBMC from a patient with chronic hepatitis C virus (HCV) infection were immortalized with EBV and plated by limiting dilution. Cultures secreting antibodies reactive in a commercial HCV II generation ELISA, which incorporates Ag derived from the nucleocapsid, NS3, and NS4 regions, were repeatedly cloned in the presence of feeder cells and growth factors. Of 23 initially immunoreactive cultures, only one cloned line, designated B12.F8, secreted HCV nucleoprotein-specific IgG1(kappa), whereas no reaction with recombinant polypeptides derived from NS3, NS4, and NS5 regions were documented. Human mAb (hmAb) B12.F8 was shown to recognize the native HCV nucleoprotein expressed in eukaryotic cells transfected with a core cDNA construct by immunofluorescence. The fine specificity of this hmAb was evaluated using synthetic oligopeptides covering the entire HCV nucleocapsid region. A weak but consistent reactivity was observed by PEPSCAN using a 12-mer encompassing residues 34-45 of the HCV-deduced amino acid sequence. Such weak reactivity is indicative for conformational epitopes and, in concurrence with this assumption, we found that longer peptides from the region containing residues 27-59 were more efficiently recognized and effectively inhibited binding of hmAb B12.F8 to recombinant nucleocapsid protein. Several overlapping immunoreactive fragments from the nucleocapsid region were selected from a random cDNA library consisting of DNase I fragments of recombinant core Ag. Best reactive recombinants were identified within residues 1-78 of the HCV sequence, in agreement with the results obtained using synthetic peptides. Comparative experiments on the fine specificity of sera from HCV-infected patients with anticore antibodies invariably showed recognition of peptides 8-40 and 27-59, as well as recombinant fragments spanning from residues 1 to 73, suggesting that hmAb B12.F8 identifies a major B cell epitope within the immunodominant nucleoprotein amino terminal subregion.

A human monoclonal antibody specific for the N terminus of the hepatitis C virus nucleocapsid protein

PBMC from a patient with chronic hepatitis C virus (HCV) infection were immortalized with EBV and plated by limiting dilution. Cultures secreting antibodies reactive in a commercial HCV II generation ELISA, which incorporates Ag derived from the nucleocapsid, NS3, and NS4 regions, were repeatedly cloned in the presence of feeder cells and growth factors. Of 23 initially immunoreactive cultures, only one cloned line, designated B12.F8, secreted HCV nucleoprotein-specific IgG1(kappa), whereas no reaction with recombinant polypeptides derived from NS3, NS4, and NS5 regions were documented. Human mAb (hmAb) B12.F8 was shown to recognize the native HCV nucleoprotein expressed in eukaryotic cells transfected with a core cDNA construct by immunofluorescence. The fine specificity of this hmAb was evaluated using synthetic oligopeptides covering the entire HCV nucleocapsid region. A weak but consistent reactivity was observed by PEPSCAN using a 12-mer encompassing residues 34-45 of the HCV-deduced amino acid sequence. Such weak reactivity is indicative for conformational epitopes and, in concurrence with this assumption, we found that longer peptides from the region containing residues 27-59 were more efficiently recognized and effectively inhibited binding of hmAb B12.F8 to recombinant nucleocapsid protein. Several overlapping immunoreactive fragments from the nucleocapsid region were selected from a random cDNA library consisting of DNase I fragments of recombinant core Ag. Best reactive recombinants were identified within residues 1-78 of the HCV sequence, in agreement with the results obtained using synthetic peptides. Comparative experiments on the fine specificity of sera from HCV-infected patients with anticore antibodies invariably showed recognition of peptides 8-40 and 27-59, as well as recombinant fragments spanning from residues 1 to 73, suggesting that hmAb B12.F8 identifies a major B cell epitope within the immunodominant nucleoprotein amino terminal subregion.

Virological features of hepatitis C virus infection in hemodialysis patients

The clinical and epidemiological relevance of circulating antibodies to hepatitis C virus (HCV) in hemodialysis patients is uncertain, since clinical signs of infection are often mild or absent, with alanine aminotransferase (ALT) values that are virtually always normal, and liver biopsies are only rarely performed. Determination of HCV RNA in serum is therefore critical for distinguishing chronic HCV infection from previous exposure to the virus. We studied HCV viremia by reverse transcription polymerase chain reaction (RT-PCR) in the 5'-noncoding region of the viral genome in 77 dialysis patients who were screened for anti-HCV by a second-generation enzyme-linked immunosorbent assay (the enzyme immunoassay II; Ortho HCV, 2nd generation, Ortho Diagnostic Systems Raritan, N.J.) and a second-generation recombinant immunoblot assay (Chiron Corporation and Ortho Diagnostic Systems) and prospectively evaluated for ALT elevations over a period of 5 years. Of 77 patients tested, 29 (38%) had active infection as shown by a positive PCR assay result, and of these, 26 were anti-HCV positive. Although a good correlation was found between circulating anti-HCV and HCV RNA in serum, 10 (28%) of 36 anti-HCV-positive patients were HCV RNA negative by PCR, suggesting either low levels of viremia or past exposure to HCV and subsequent recovery. On the other hand, 3 (7.3%) of 41 anti-HCV-negative patients had HCV RNA in their sera, indicating seronegative HCV infection. The ALT level had no predictive value for HCV infection, because it was repeatedly normal in 18 (62%) of 29 viremic patients. HCV genotyping was also performed and indicated that all four known genotypes of HCV were present in our group. In conclusion, serological assays are reliable for detecting exposure to HCV in hemodialysis patients; however, direct identification of the viral genome is required to document current infection.

Properties of a human monoclonal antibody specific for the NS4 region of hepatitis C virus

A human monoclonal IgG1(kappa) antibody (hmAb) specific for a sequential epitope comprised within the 5-1-1 fragment of the NS4 region of hepatitis C virus (HCV) has been recently generated (1). In this study, B-cell clone supernatant containing the hmAb was purified by passage over a protein A affinity column. Preincubation with synthetic oligopeptides containing the epitope recognized by the hmAb resulted in complete inhibition of binding to the whole recombinant protein, attesting to its specificity. Calculation of the dissociation constant (Kd) using a synthetic 20-mer as antigen gave a value of 3.3372 x 10(-8) M, consistent with that of a human IgG. We predict that this hmAb will be helpful in characterizing the as yet unidentified native NS4 protein of HCV.

Monoclonal antibodies to human DNA topoisomerase I and the two isoforms of DNA topoisomerase II: 170- and 180-kDa isozymes

Several monoclonal antibodies of different isotypes specific to human DNA topoisomerase I, to 170- and 180-kDa DNA topoisomerase II isozymes, were produced and characterized. The specificity of monoclonal antibodies was confirmed by comparison with polyclonal antibodies by Western blot, by immunoprecipitation of enzyme activity, and by immunoprecipitation of DNA topoisomerases with characterized polyclonal antisera. Morphological studies performed by immunofluorescence indicate that the three groups of monoclonal antibodies (MoAbs) stain the nucleus with characteristic patterns, which can be compared with those obtained with polyclonal antibodies. In particular the MoAbs to the 100-kDa DNA topoisomerase I stain the nucleolus and the nucleoplasm; the MoAbs to 170- and 180-kDa DNA topoisomerase II give completely distinct intranuclear patterns: those to the 170-kDa protein stain mainly the nucleoplasm, whereas those to the 180-kDa protein stain only the nucleolus. The two DNA topoisomerase II isozymes clearly exhibit fluctuations in their expression during cell growth: the 170-kDa isozyme is more abundant during the logarithmic phase of growth, while the 180-kDa isozyme is mainly present during the plateau phase of growth.

High prevalence of antibodies to hepatitis C virus in hemodialysis units using a second generation assay

We studied the prevalence and significance of antibodies to hepatitis C virus (HCV) in patients and staff from 3 dialysis units, using a 2nd generation assay (2nd g.a.; Ortho HCV). Of 277 patients, 151 (55%) were positive by 2nd and 85 (31%) by 1st g.a. Significant associations with the anti-HCV carrier status were: blood transfusions, retrospective finding of elevated ALT and duration of dialysis treatment, independently of transfusions. Of the 74 staff members, 5 were positive by 2nd and 3 by 1st g.a. Our data suggest that the 2nd g.a. is more sensitive in detecting HCV exposure in dialysis units and that duration of dialysis is a significant factor in acquiring HCV infection.

Identification of an immunodominant B cell epitope on the hepatitis C virus nonstructural region defined by human monoclonal antibodies

Several EBV-transformed B cell lines (BCL) were obtained from two patients with chronic hepatitis C virus (HCV) infection that secreted IgG class antibodies to the HCV nonstructural Ag c100-3. Two cloned BCL, derived from the same parental line, generated stable cloned lines that secreted up to 20 mg/liter of specific IgG1(kappa). Supernatants from oligoclonal and cloned BCL were also analyzed by immunoblot and all strongly reacted with recombinant polypeptides derived from the putative NS4 region of HCV, c100-3 and 5-1-1 (a 42-amino acid fragment of c100-3), whereas no reaction with the viral nucleoprotein, the NS3 nonstructural protein or the superoxide dismutase moiety of the c100-3 fusion protein could be documented. The fine specificity of these antibodies was also evaluated using overlapping synthetic peptides (20-mers) covering the 5-1-1 sequence. All oligoclonal and clonal IgG displayed high affinity binding to peptides covering residues 120-137 of Chiron's c100-3 sequence at the aminoterminus of 5-1-1. In addition, a minimal B cell epitope, N-VLYREF-C, was defined by human oligoclonal and monoclonal antibodies corresponding to residues 132-137. Interestingly, predominant recognition of the N-terminus of 5-1-1 was also observed in more than 80% of sera from patients with HCV infection. In conclusion, we have successfully produced human B cell cloned lines that secrete abundant quantities of IgG1(kappa)-specific for a polypeptide encoded by the NS4 region of HCV. Such antibodies recognize an immunodominant epitope, relative to this region, located at the N-terminus of the 5-1-1 fragment.

Identification of an immunodominant B cell epitope on the hepatitis C virus nonstructural region defined by human monoclonal antibodies

Several EBV-transformed B cell lines (BCL) were obtained from two patients with chronic hepatitis C virus (HCV) infection that secreted IgG class antibodies to the HCV nonstructural Ag c100-3. Two cloned BCL, derived from the same parental line, generated stable cloned lines that secreted up to 20 mg/liter of specific IgG1(kappa). Supernatants from oligoclonal and cloned BCL were also analyzed by immunoblot and all strongly reacted with recombinant polypeptides derived from the putative NS4 region of HCV, c100-3 and 5-1-1 (a 42-amino acid fragment of c100-3), whereas no reaction with the viral nucleoprotein, the NS3 nonstructural protein or the superoxide dismutase moiety of the c100-3 fusion protein could be documented. The fine specificity of these antibodies was also evaluated using overlapping synthetic peptides (20-mers) covering the 5-1-1 sequence. All oligoclonal and clonal IgG displayed high affinity binding to peptides covering residues 120-137 of Chiron's c100-3 sequence at the aminoterminus of 5-1-1. In addition, a minimal B cell epitope, N-VLYREF-C, was defined by human oligoclonal and monoclonal antibodies corresponding to residues 132-137. Interestingly, predominant recognition of the N-terminus of 5-1-1 was also observed in more than 80% of sera from patients with HCV infection. In conclusion, we have successfully produced human B cell cloned lines that secrete abundant quantities of IgG1(kappa)-specific for a polypeptide encoded by the NS4 region of HCV. Such antibodies recognize an immunodominant epitope, relative to this region, located at the N-terminus of the 5-1-1 fragment.

Friedreich ataxia in Italian families: genetic homogeneity and linkage disequilibrium with the marker loci D9S5 and D9S15

Friedreich ataxia (FA) is an autosomal recessive degenerative disease of the nervous system of unknown biochemical cause. The FA gene has been shown to be in close linkage with the two chromosome 9 markers D9S5 and D9S15, and linkage disequilibrium between FA and D9S15 has been detected in French families by Hanauer et al. We used new highly informative markers at the above loci to analyze Italian FA families for linkage and linkage disequilibrium. The new markers were a three-allele BstXI RFLP at D9S5 (PIC = .55) and a six-allele microsatellite, typed by polymerase chain reaction, at D9S15 (PIC = .75). We obtained maximum lod scores of 8.25 between FA and D9S5, 10.55 between FA and D9S15, and 9.52 between D9S5 and D9S15, all at zero recombination. Our results, combined with those reported by other authors, reduce maxlod-1 (maximum lod score minus 1) confidence limits to less than 1.1 cM between FA and D9S5, 1.2 cM between FA and D9S15, and 1.4 cM between D9S5 and D9S15. Linkage disequilibrium with FA was found only for D9S15 when all families were evaluated but was also found for a D9S5/D9S15 haplotype in a subgroup of southern Italian families. We conclude that FA, D9S5, and D9S15 are tightly clustered and that studies of geographically restricted groups may reveal a limited number of mutations responsible for the disease in the Italian population. We present preliminary evidence from pulsed-field gel electrophoresis that D9S5 and D9S15 may be less than 450 kb apart. Linkage disequilibrium between FA and D9S15 suggests that the disease gene may be at an even shorter distance from this marker locus, which therefore represents a very good starting point for cloning attempts.

Antibodies from patients with rheumatoid arthritis and systemic lupus erythematosus recognize different epitopes of a single heterogeneous nuclear RNP core protein. Possible role of cross-reacting antikeratin antibodies

Antibodies to recombinant heterogeneous nuclear RNP core protein A1 were detected in sera from 27 of 58 patients with rheumatoid arthritis (RA) and from 7 of 31 patients with systemic lupus erythematosus, by immunoblotting and enzyme-linked immunosorbent assay. Protein A1 consists of 2 distinct domains: The N-terminal sequence is identical to a single-stranded DNA binding protein termed UP1, and the C-terminal domain shows a partial homology with keratin. All 7 A1-positive systemic lupus erythematosus sera reacted with UP1, whereas 9 of the 27 A1-positive RA sera did not. In RA, anti-A1 activity was significantly associated with antikeratin antibodies (AKA); these antibodies were present in 23 of 27 A1-positive sera and 10 of 31 A1-negative sera (P less than 0.01). Immunoabsorption with recombinant protein A1 resulted in a significant reduction of AKA titers in 6 of 10 RA sera tested, suggesting that AKA from RA patients may cross-react with the C-terminal portion of the heterogeneous nuclear RNP protein A1.

Autoantibodies to poly(ADP-ribose)polymerase in autoimmune diseases

Antibodies to various nuclear proteins are frequently found in sera of patients affected by connective tissue diseases and other autoimmune diseases. We investigated the specificity of circulating autoantibodies to poly(ADP-ribose)polymerase (pADPRP) in different autoimmune and connective tissue diseases: Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA), Progressive Systemic Sclerosis (PSS), Sjogren's Syndrome (SS), Undifferentiated Connective Tissue Disease (UCTD), Cryptogenic Fibrosing Alveolitis (CFA) and Sarcoidosis. pADPRP was purified from calf thymus. Antibody specificity was detected by ELISA, western blot and enzyme activity precipitation. Positive values (mean O.D. values + 3 S.D. of 36 normal controls) were obtained in 7/15 SLE patients, 1/18 RA patients, 1/30 PSS, 3/14 SS, 0/5 UCTD, 5/21 CFA and 4/25 Sarcoidosis. The positive sera also recognized the pADPRP protein when tested by western blot. Furthermore the enzyme activity was inhibited after immunoprecipitation by some highly positive sera.

Antibodies to hnRNP core protein A1 in connective tissue diseases

We investigated the specificity of circulating autoantibodies to a heterogeneous nuclear ribonuclear protein A1 (hnRNP A1), obtained by recombinant DNA technique, in different rheumatic diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), scleroderma, primary Sjogren's syndrome (SS), idiopathic Raynaud (IR), mixed connective tissue disease (MCTD), and healthy donors. All sera were tested by ELISA on hnRNP A1 protein. Positive values were obtained in 22% SLE, 19% scleroderma, 10% IR, 40% (2/5) MCTD, 5% SS, and 50% RA patients. The majority of patients reacted with the aminoterminal part (UP1) of hnRNP A1; however, some RA patients reacted also with the carboxy-terminal part that shows partial homology with keratin. Therefore, hnRNP A1 (UP1) can be considered a target of antinuclear autoimmunity in various rheumatic disorders.

Anti-SSB/La antibodies in Sjögren's syndrome and related autoimmune diseases. Results of a quantitative immunoassay using a highly purified antigen

A quantitative immunoassay using a highly purified antigen from HeLa cells has allowed us to detect antibodies to SSB/La in 11/20 patients with primary Sjögren's syndrome (SS), 15/33 with SLE, and 11/35 with progressive systemic sclerosis (PSS). However, positive results were found in only 2/12 patients with idiopathic Raynaud's disease and 2/20 with rheumatoid arthritis, including 4 with secondary SS. Anti-SSB/La were associated with extraglandular manifestations in primary SS, and with a diffuse sclerodermic pattern in PSS. In SS, SLE and PSS, a positive anti-SSB/La test was strongly associated with nodal or spleen enlargement and with an increased level of gamma-globulins. A direct association was also found with positive tests for rheumatoid factors, anti-SSA/Ro and anti-Scl 70. An inverse relationship was however found with anti-nRNP +/- Sm and anticentromere antibodies. Our data suggest that anti-SSB/La antibodies can be regarded as a marker of B-lymphocyte activation in patients with either primary SS, SLE or PSS.

Carboxyethyl gamma-aminobutyric acid, a polyamine derivative, improves the recovery of EBV-transformed lymphocytes

A polyamine derivative, carboxyethyl - Aminobutyric Acid (CEGABA), induces the formation of a large number of Epstein-Barr Virus (EBV) transformed lymphocytes, when added to the culture medium immediately after EBV infection. However, CEGABA shows only a moderate effect on the stability of EBV-transformed cell lines over time, and does not affect the growth of stabilized cell lines. It is possible that CEGABA acts on cells other than EBV transformed lymphocytes (in fact, after EBV infection all types of mononuclear cells from the blood are present in the culture) and indirectly promotes the growth of EBV transformed lymphocytes.

Improvements of Western blotting to detect monoclonal antibodies

A comparison of the effects of different factors on the sensitivity of Western blotting technique to detect monoclonal antibodies is described. The major improvements were obtained by: A) renaturating the antigen in the gel before transferring it in carbonate buffer at pH 10 onto nitrocellulose and B) using alkaline-phosphatase-conjugated second antibody instead of peroxidase-conjugated second antibody.

Autoantibodies to purified nuclear proteins related to DNA metabolism during ageing and in SLE patients

In this study the specificity of circulating autoantibodies in ANA+ aged donors, ANA- donors and SLE patients was investigated by immunoblotting on total nuclear proteins and by ELISA on purified nuclear proteins, possibly related to DNA metabolism, such as DNA polymerase alpha, DNA-dependent ATPase, DNA Topoisomerase I, ssDBP, hnRNP, HMG and histones. Immunoblotting showed that sera from ANA+ aged donors present fewer antibodies to nuclear proteins, especially to those between 21,000 and 45,000, molecular weight (MW), than sera from SLE patients. When the specificity of antisera was further studied on purified nuclear proteins, it was found that the majority of sera from SLE patients react with most of the proteins tested, whereas sera from ANA+ aged donors mainly react with DNA polymerase alpha, DNA-dependent ATPase, DNA Topoisomerase I and histones. In addition, sera from a few ANA- donors also reacted with certain purified nuclear proteins in a statistically significant age-related manner.

Carboxyethyl gamma-aminobutyric acid, a polyamine derivative molecule with a growth effect on hybridomas

An increased proliferation of hybridomas is induced by a polyamine derivative molecule, CEGABA (carboxyethyl gamma-aminobutyric acid). The effects of CEGABA and CR-ECGS (endothelial cell growth supplement) on hybridoma growth are similar. However, both factors are less efficient than HECS (human endothelial culture supernatant) in inducing hybridoma growth through all the steps of hybridoma production, including: recovery after fusion, cloning, and proliferation.