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Biomedical subjects

N E Cremer

Publications and source records attributed to N E Cremer.

At least 19 recordsLinked to original sources
PubMed1985

Antibody response to cytomegalovirus polypeptides captured by monoclonal antibodies on the solid phase in enzyme immunoassays.

Antibodies to different cytomegalovirus (CMV) polypeptide antigens, captured by monoclonal antibodies coated on the solid phase of an enzyme immunoassay test, were analyzed in 42 serum pairs submitted for serodiagnosis of CMV infection. Three CMV antigens, captured on the solid phase by three monoclonal antibodies of different specificities, designated CH92-1, CH65-1, and CH16-1, were glycoproteins A (gA), gC, and gD, respectively; and one antigen, captured by CH23, was a polypeptide with an apparent molecular weight of 150,000, possibly associated with the nucleocapsid. Of these four CMV antigens, gA captured by CH92-1 was most effective in eliciting an antibody response. Antibody to this antigen was present in serum samples at a higher concentration in primary and reactivated infection and persisted longer than did antibody to the other tested antigens. In contrast, antibody to antigen captured by CH23 was at a lower concentration, rose more slowly in infection, and persisted for a shorter time than did antibody to the other antigens. Antibody response to gC and gD was intermediate in concentration and temporal appearance compared with the antibody response to gA and to the polypeptide bound by CH23. An enzyme immunoassay on paired serum samples with the captured glycoproteins as antigen was equal for the detection of current infection to an enzyme immunoassay with the whole CMV antigen from infected cell lysates. Enzyme immunoassays with either the CMV glycoproteins or the whole CMV antigen from infected cell lysates were superior to a complement fixation test with a glycine extract antigen for serodiagnosis of current infection.

Antibodies, Monoclonal↗
PubMed1985

Enzyme immunoassay versus plaque neutralization and other methods for determination of immune status to measles and varicella-zoster viruses and versus complement fixation for serodiagnosis of infections with those viruses.

Results by an enzyme immunoassay method (EIA) performed at one serum dilution and results by indirect immunofluorescence (IFA) and hemagglutination inhibition (HI) tests performed at step dilutions were correlated with results by a neutralization test (50% plaque neutralization [PN]) performed at step dilutions on single serum samples for serologic evaluation of immunity status to measles virus. PN results were taken as true indicators of immunity, and the other tests were evaluated on that basis. The predictive value of a positive result being positive also by PN was 95.3% for HI and 93.3% for EIA and IFA. The predictive value of a negative result being negative also by PN was 81.1% for HI, 100% for EIA, and 75.0% for IFA. A similar study on immunity status to varicella-zoster virus by EIA and by an anticomplement immunofluorescence test versus PN showed a 100% predictive value of a positive or negative result by EIA. By the anticomplement immunofluorescence test, the predictive value of a positive result was 97.7%, and that of a negative result was 88.5%. Studies on the comparative ability of EIA versus complement fixation (CF) to detect significant changes in antibody concentration between acute-phase and convalescent-phase serum samples indicative of a current infection were also done. Both tests were satisfactory for the serodiagnosis of measles or varicella-zoster virus infections. However, EIA was preferable to CF because it was less technically difficult, less labor intensive, and could be performed on sera that were anticomplementary in CF reactions.

Antigens, Viral↗
PubMed1984

Detection of IgG antibodies to measles virus using monoclonal antibodies for antigen-capture in enzyme immunoassay.

An enzyme immunoassay (EIA) for the detection of IgG antibodies to measles viral hemagglutinin (H) has been developed. Monoclonal antibodies were employed as antigen-capture reagents on a polystyrene ball solid phase. The antigen-capture EIA was significantly more sensitive than hemagglutination inhibition (HAI) and somewhat more sensitive than indirect immunofluorescence and indirect EIA for the detection of antibodies to measles virus. The importance of selecting a monoclonal antibody with a high binding affinity, and controlling for non-specific adherence of antigen or antibodies to the solid phase were demonstrated. This method offers not only greater sensitivity than HAI, but also the practicality of reagents capable of standardization and long term storage.

Antibodies, Monoclonal↗
PubMed1984

Biological activity of a monoclonal antibody to a measles virus haemagglutinin epitope detected late in infection.

A hybrid cell line secreting monoclonal antibody 2H9c (mAb 2H9c) with measles virus haemagglutinin (HA) specificity was produced. The mAb 2H9c was non-reactive in haemagglutination inhibition and neutralization assays. A protein of apparent mol. wt. 79000 was immune-precipitated using a Triton X-100/SDS/sodium deoxycholate detergent buffer and two proteins with mol. wt. of 79000 and 69000 were immune-precipitated using 1% Nonidet P40/sodium deoxycholate buffer in SDS-PAGE assays. Similar results were obtained with other anti-HA monoclonal antibodies, supporting the assumption that mAb 2H9c was directed against the HA polypeptide. The indirect immunofluorescence (IFA) staining pattern of acetone-fixed infected cells with mAb 2H9c differed substantially from that with other HA-specific monoclonal antibodies. Kinetic studies revealed that the reactivity of mAb 2H9c lagged behind other HA-specific monoclonal antibodies by 18 to 36 h post-infection in IFA assays. This suggests that mAb 2H9c may be directed against a binding site that arises late in infection, possibly as a result of a conformational alteration of the HA polypeptide.

Animals↗
PubMed1984

Anomalous antibody responses in viral infection: specific stimulation or polyclonal activation?

Eighteen paired serum samples submitted for serodiagnosis of current infection showed anomalous antibody results by complement fixation test when tested with a battery of agents (viruses, Mycoplasma pneumoniae, and chlamydia) selected for testing on the basis of the symptoms of the patient. Seventeen serum pairs showed a fourfold or greater rise in titer of antibody to two agents in the battery, and one showed only a twofold rise in titer of antibody to the identified causative agent but an eightfold rise in titer of antibody to a heterologous agent. The 18 serum pairs were tested for IgM antibody to the two involved agents to determine whether IgM antibody tests would better distinguish the probable cause of the current infection. The serum pairs were separated into three groups based on their IgM responses. Group I consisted of six serum pairs with IgM antibody to both agents, four pairs of which showed a fourfold or greater rise in titer of IgM antibody to both agents, and two of which showed a rise in titer of IgM antibody to only one of the two agents. Group II consisted of 10 serum pairs with IgM antibody to one of the two agents, 7 pairs of which showed a fourfold or greater rise in titer of IgM antibody to the agent. Group III consisted of two serum pairs with no IgM antibody to either agent. Results show that determination of presence or absence of IgM antibody per se or demonstration of a fourfold or greater rise in specific IgM antibody titer does not always help in distinguishing the causative agent in current infections.

Adolescent↗
PubMed1983

Discriminant analysis of data in enzyme immunoassay.

A critical step in the development of both qualitative and quantitative enzyme immunoassays is establishing the positive/negative discrimination, or cut-off, value. Data derived from an indirect immunofluorescence assay, hemagglutination inhibition, and enzyme immunoassay to detect IgG antibodies to measles virus were applied to a discriminant analysis program to determine the positive/negative cut-off value. Application of the discriminant analysis demonstrated a greater utilization of the sensitivity of the enzyme immunoassay than the most commonly used methods. This method also illustrates the importance of examining both antibody positive and negative sera, rather than negative sera alone, in determining the cut-off value. In addition, probability of membership in the antibody positive or negative group is included in the determination. This increases the information base for risk assessment and clinical evaluation.

Antibodies, Viral↗
PubMed1983

Lymphocyte migration in inbred Syrian hamsters with acute measles virus encephalitis.

The migratory pattern of 51Cr-labeled adult lymphocytes, as measured by 51Cr concentration in various tissues, was followed in inbred weanling Syrian hamsters infected intracranially with measles virus. Donor-labeled lymphocytes were inoculated intracardially into infected and control recipients. Increased passage of labeled lymphocytes across the blood-brain barrier was first seen on day 3 post virus inoculation and 1 day prior to development of clinical signs of acute measles encephalitis. 51Cr concentration in the brain increased progressively along with neurologic signs until the death of the hamsters. Aberration of lymphocyte migration peripherally, manifested by reduced presence of labeled cells in lymph nodes and spleen, first occurred 4 days post virus inoculation in those hamsters with clinical signs of disease. By days 5 and 6 post virus inoculation, the concentration of 51Cr in lymph nodes was 30% and 20%, respectively, of that in lymph nodes of control hamsters. Concentration of labeled lymphocytes in lymph nodes and spleen of the occasional virus-inoculated animal that appeared clinically well at time of autopsy was always greater than that in ill hamsters, and was closer to and sometimes equal to the concentration in the corresponding tissues of control hamsters. Thus, increased passage of labeled lymphocytes into the brain and decreased recovery of labeled lymphocytes in lymph nodes and spleen occurred concomitantly with increased neurologic signs of disease. No differences in presence of labeled cells in other tissues tested (liver, lung, thymus and blood) between infected and control hamsters were noted. Labeled lymphocytes from either measles virus or ovalbumin-immunized donors appeared to pass more readily into the brains of ill recipients than labeled lymphocytes from unimmunized donors.

Animals↗
PubMed1983

Improved serological diagnosis of rubella.

The use of an enzyme immunoassay-immunoglobulin G antibody test instead of the hemagglutination inhibition test as a primary test for the serological diagnosis of current infection, with complement fixation as an alternate test for use when enzyme immunoassay results are high and stationary, improved the serological diagnosis of rubella.

Complement Fixation Tests↗
PubMed1982

Cell-mediated cytotoxicity toward measles virus-infected target cells in randomly bred Syrian hamsters.

Cell-mediated cytotoxicity (CMC) toward measles virus-infected cells was studied by a (51)Cr release assay with spleen cells from hamsters inoculated with measles virus (strain Lec) or control antigen and with spleen cells from normal hamsters. Spleen cells from measles virus-inoculated hamsters showed greater CMC toward infected than toward noninfected target cells (designated specific CMC). Specific CMC was maximal 7 days after virus inoculation and was declining by 9 to 10 days. Effector cells were present in a nonadherent cell population. Specific CMC was reduced after treatments of effector cells with antithymocyte serum plus complement. The decrease in cytotoxicity was greater toward infected target cells than toward noninfected target cells. Treatment of infected target cells with antimeasles serum did not increase specific CMC by effector cells from the majority of virus-inoculated hamsters. CMC toward infected target cells by normal spleen cells (natural killer cells) or spleen cells from hamsters inoculated with control antigen was approximately the same as, or more often less than, CMC toward noninfected target cells. Natural killer cells were present in a nonadherent cell population. Treatment of natural killer cells with antithymocyte serum plus complement caused a similar decrease in cytotoxicity toward both infected and noninfected target cells. This study demonstrated virus-specific cellular cytotoxicity of effector spleen cells from measles virus-inoculated hamsters. Although the data were compatible with T cells as the source of effector cells in the virus-specific CMC, definitive identification could not be made. Additional membrane markers for better characterization of hamster lymphocyte subpopulations are required.

Animals↗
PubMed1982

Evaluation and reporting of enzyme immunoassay determinations of antibody to herpes simplex virus in sera and cerebrospinal fluid.

Several methods for evaluating and reporting enzyme immunoassay (EIA) determinations of antibody to herpes simplex virus derived from one dilution of single serum samples were studied. An EIA ratio method for serological evidence of current infection from paired serum samples was also evaluated. Optical density (OD) of the reaction at a 1:100 serum dilution and estimated titers obtained by reference of the OD of the serum dilution to a standard curve were compared to the corresponding plotted EIA titer obtained by titration to endpoint. Neither the OD per se nor the estimated titer was completely predictive of the plotted titer (correlation coefficient [r] of 0.824 and 0.817, respectively), and they provided only a semiquantitative measurement of antibody concentration. For an antibody status report, however, OD would be sufficient if related to the cutoff value as an EIA index (OD of sample divided by cutoff OD for positive specimens). The OD of the EIA reaction at a single dilution (1:5) of cerebrospinal fluid, on the other hand, correlated quite well with the titer obtained by titration (r = 0.950). For serological diagnosis of current infection, the OD ratio of convalescence-phase/acute-phase sera was determined at several dilutions. A ratio of greater than or equal to 1.54 was calculated as a reliable index for a significant rise in antibody concentration and compatible with current infection. By determining the convalescent-phase/acute-phase serum ratio at two dilutions, 1:100 and 1:1,000, the EIA ratio method appeared to be a sensitive as or more sensitive than, complement fixation in diagnosing current infection.

Antibodies, Viral↗
PubMed1980

Comprehensive viral immunology of multiple sclerosis. II. Analysis of serum and CSF antibodies by standard serologic methods.

Sera and CSFs of 85 patients with multiple sclerosis (MS), 49 patients with probable MS, and 165 control patients with other neurologic diseases were assayed for antibodies to rubella, mumps, measles, parainfluenza I (strain 6/94), herpes simplex, cytomegalovirus, varicella-zoster, and vaccinia viruses. Methods included complement fixation (CF), hemagglutination inhibition (HI), and complement-dependent plaque reduction (CPR). Significant differences between the groups with MS and the control groups were higher serum antibody titers to measles virus in the groups with MS, higher proportion of patients with MS with CSF antibodies to measles, rubella, and vaccinia viruses, and greater percentage of patients with MS with more than one CSF viral antibody. Duration and severity of disease in the patients with MS were associated with presence of multiple CSF antibodies. Presence of CSF antibody was positively correlated with the height of the correspnding serum titer, yet a high serum titer did not ensure the presence of CSF antibody. Oligoclonal bands were present in the CSFs of equal proportions of patients with MS with and without CSF viral antibody. Our data support the hypothesis of local antibody synthesis within the CNS. However, we favor the view that preprogrammed antibody-forming lymphocytes enter the CNS and then produce antibody either because of nonspecific polyclonal activation in situ or because of failure of normal regulation.

Antibodies, Viral↗
PubMed1980

Comprehensive viral immunology of multiple sclerosis. III. Analysis of CSF antibodies by radioimmunoassay.

The CSF from 279 patients with multiple sclerosis (MS), probable MS, or controls was examined by radioimmunoassay (RIA) for antibodies to measles, rubella, mumps, parainfluenza 1 (Sendai) (strain 6/94), herpes simplex (HSV), varicella, and vaccinia viruses. Significantly more patients with MS than noninflammatory control patients had antibody to measles, rubella and varicella viruses, of which antibody to measles was the most prevalent. The percentage of patients with MS with two or more CSF antibodies was significantly greater than that in the controls. There was no tendency for certain antibodies to be associated. There was a general relationship between presence of CSF antibodies and severity of MS. The data support the hypothesis of local CNS antibody synthesis of several viral antibodies; however, such local synthesis may be a random event, possibly dependent on the number and specificity of peripheral virus antibody-forming lymphocytes available for ingress into the CNS.

Albumins↗
PubMed1980

Differentiation of cytomegalovirus antigens by their reactivity with various classes of human antibodies in the indirect fluorescent antibody test.

Human sera containing immunoglobulin G (IgG), IgA, and IgM antibodies were tested by immunofluorescence for reactivity with cytomegalovirus-infected cell cultures and with early antigens of cytomegalovirus produced by treating the infected cultures with either bromodeoxyuridine or cytosine arabinoside. IgG antibody but not IgM antibody reacted with early antigens produced in bromodeoxyuridine-treated infected cultures. This observation on a small sample of sera suggested that a positive IgM reaction with an infected, nontreated culture and a negative reaction with a bromodeoxyuridine-treated infected culture may indicate a positive specific IgM reaction for cytomegalovirus, even in the presence of IgM rhematoid factor. The hyothesis requires further testing. The different classes of antibody did not all react or did not react to the same extent with early antigens produced in infected cells blocked with cytosine arabinoside or bromodeoxyuridine. This observation indicates that different antigens were being produced as a result of the two treatments.

Antigen-Antibody Reactions↗
PubMed1979

Cyclic expression of antigen and infectious virus in a BHK cell line (0-853) persistently infected with an SSPE strain of measles virus.

Establishment and characteristics of a baby hamster kidney cell line (BHK 0-853) persistently infected with a subacute sclerosing panencephalitis (SSPE) strain of measles virus (Lec strain) is described. The persistent infection was easily and repeatedly established and no special conditions were required. There was a predictable fluctuation in expression of virus intracellular and membrane antigens which varied from greater than 90% to less than 1% of the cells demonstrating these antigens during the first 6 or 7 passages. Thereafter, fluctuation of antigen and infectious virus expression continued in an unpredictable fashion.

Animals↗
PubMed1979

Cytotoxic antibody to cells infected with measles virus in serum and cerebrospinal fluid of multiple sclerosis and control patients.

Sera and cerebrospinal fluids (CSFs) from 66 patients selected from a larger sample of multiple sclerosis (MS) and control patients were studied for presence of complement-dependent cytotoxic (CT) antibody against baby hamster kidney cells infected with measles virus, strain Lec. The MS group contained 26 patients with clinically definite disease and 7 with probable MS. Seventeen of the 33 patients selected from the MS group had hemagglutination-inhibiting (HI) antibody to measles virus in their CSFs. Specimens from 33 control patients with other identifiable neurological disorders were matched according to the time of specimen sampling and with the age of the donors. Seven of the controls had HI CSF antibody. The serum CT geometric mean antibody titer of the MS group was approximately twofold higher than that of the control group. Forty-two percent of the MS group and 18% of the control group had CT antibody in the CSF. With the exception of the ratio of one control patient, the serum/CSF ratios of CT antibody from all patients were 128 or less. Nine CSFs (six MS and three control specimens) had CT antibody but no detectable HI antibody. Conversely, 12 CSFs (eight MS and four control specimens) had HI antibody but no detectable CT antibody. Five patients in the MS group with both kinds of CSF antibodies had reduced CT ratios but normal HI ratios. The results suggest that the two tests detect CSF antibodies reactive with different antigens. In this study, where less than half of the MS patients displayed CSF CT antibody, it is unlikely that such antibodies play an active role in the pathogenetic mechanism operative in the disease.

Antibodies, Viral↗