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Biomedical subjects

G C Blanchard

Publications and source records attributed to G C Blanchard.

18 recordsLinked to original sources
PubMed1993

Partial purification and identification of an immunosuppressive factor in AIDS sera.

The cause of the profound immunodeficiency state induced by the human immunodeficiency virus (HIV) is not yet fully understood. Although direct cytopathic effects of the virus leading to the loss of CD4+ lymphocytes are believed to play a major role, soluble factors that cause lymphocyte dysfunction have also been identified. Here, we demonstrate that sera of AIDS patients contain a viral component capable of profoundly inhibiting normal T lymphocyte and natural killer cell functions. This factor (M(r) 30,000-50,000) is relatively resistant to proteolytic degradation, heat denaturation, extreme pH, and chemical modifications. It has been determined by Western blotting to share epitopes with the gp41 viral transmembrane component of HIV-1. This immunosuppressive factor has the characteristic property of inhibiting lymphocyte activation in the early stage (within 3 hr) of mitogenic stimulation. Concomitant with the inhibition of lymphocyte activation and interleukin 2 (IL-2) production, transcription of the IL-2 message is also reduced in a time-dependent manner. The unique time dependency of this immunosuppressive factor in lymphocyte activation could serve as a valuable tool to study the early steps of signal transduction in lymphocyte activation beyond membrane interaction.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Identification of HIV-1 envelope glycoprotein in the serum of AIDS and ARC patients.

Binding of the human immunodeficiency virus type 1 (HIV-1) external envelope glycoprotein (gp120) has been reported to alter the function and surface antigen expression of lymphocytes and monocytes in vitro. To determine whether these in vitro findings could be relevant in vivo, we searched for the presence of this antigen in the serum of patients with AIDS and the AIDS-related complex (ARC). Using an antigen capture enzyme-linked immunosorbent assay (ELISA) with polyclonal anti-gp120 antibody, we detected envelope antigens (gp160/120) in serum of 22 of 32 AIDS patients. In contrast, an ELISA using solid-phase recombinant CD4 to capture gp160/120 failed to detect any positives. A modification of the anti-gp120-based ELISA identified gp160/120-IgG immune complexes in all of 11 AIDS patients tested and in 4 ARC patients who were negative for gp160/120 antigen. We conclude that gp160/120, predominantly in the form of immune complexes, can be identified as circulating antigen in patients with AIDS. The potential pathogenic consequences of this antigenemia, its relation to soluble CD4 therapy, and its application as a clinical marker of disease merit further study.

AIDS-Related Complex↗
PubMed1990

Regeneration of immunosorbent surfaces used in clinical, industrial and environmental biosensors. Role of covalent and non-covalent interactions.

The durability and regeneration of antibodies immobilized to commercial immunosorbents were investigated by monitoring Ag-Ab dissociation. Solutions consisting of 0.01 M hydrochloric acid (HCl), 10% propionic acid, 50% ethylene glycol and 10% SDS in 6 M urea were used in the evaluation of antigen dissociation from antibody covalently immobilized to glass and polystyrene beads, microtiter plates and Immobilon filters. RAH-IgG, used as a model antibody, bound strongly to all covalent surfaces. However, on adsorption to Nunc-1 microtiter plates, 25-60% of RAH-IgG was removed by all dissociating solutions. Covalent binding to Sanger beads was weakest relative to other covalent surfaces, exhibiting 30% and 65% detachment with ethylene glycol and SDS in urea, respectively. Although all four solutions dissociated antigen from surface-bound antibody, HCl and propionic acid were more effective on most surfaces. The antibody remained functional following antigen dissociation and reassociated to nearly 100% on all surfaces except Sanger beads and Nunc-1 microtiter plates. This study was initiated to evaluate regeneration and reuse of microelisa plates and emerging biosensors as a means of reducing routine laboratory analysis costs. Data are presented to demonstrate the reusability of microtiter plates in ELISAs following antigen dissociation from covalently bound antibody.

Antigen-Antibody Complex↗
PubMed1987

Tumor regression and temporary restoration of immune response after plasmapheresis in a patient with recurrent oral cancer.

A major response to plasmapheresis is reported in a patient with advanced, recurrent squamous cell cancer of the oral cavity, similar to that previously reported in three of six comparable patients. Tumor regression followed temporary reduction of inhibition of normal lymphocyte response to phytohemagglutinin (PHA) by the patient's serum (from 99% to zero) and partial restoration of the patient's lymphocyte response (from 2% to 38% of control). The IgE level rose both overall and during some exchanges; this correlate of tumor response had been noted earlier. The tumor showed extensive necrosis, but the clinical effects were relatively short-lived and the patient died 11 weeks later. Biopsy specimens taken early in apheresis showed intense new infiltration of tumor by lymphocytes and monocytes; later biopsy specimens showed predominantly plasma cells with trapping and lysis of tumor cells. No other anti-cancer therapies had been used for 16 months before this trial, and no replacements were given other than saline and albumin.

Antigens, Surface↗
PubMed1987

Lung nonresponsiveness produced in guinea pigs by aerosolized antigen. I. Nonresponsiveness is not antigen specific.

Nonresponsiveness to aerosolized antigen induced by repeated exposure of guinea pigs to either bovine serum albumin (BSA) or ragweed (RW) aerosols was not antigen specific, since induction of lung sensitization with the same, as well as heterologous antigen, was prevented. However, prior lung sensitization to an antigen was maintained in spite of subsequent treatment with aerosolized antigen. In this case treatment with aerosolized antigen could abrogate sensitization of the lung to all subsequent antigens. Chopped lung pieces could not be passively sensitized by antisera to homologous or heterologous antigens unless they were previously treated at low pH. High levels of conventional and homocytotropic antibody were demonstrated in nonresponder animals. Nonresponsiveness induced by fed antigen, however, was antigen specific, and elevated homocytotropic antibody levels were not present. Aerosol-induced nonresponsiveness appears to be a local phenomenon which involves a blocking of the pulmonary mast cells by immune complexes or other blocking factors so that they can no longer respond to antigen challenge.

Aerosols↗
PubMed1985

Plasma exchange in six patients with advanced cancers of the head and neck.

Six patients with advanced squamous cell cancers of the head and neck, with serum IgA greater than or equal to 400 mg/dl and IgE less than or equal to 1000 IU/ml, underwent a trial of six 2-liter plasma exchanges over a 2-3-week period. Disease progressed in patients 1, 2, and 4, who died on days 44, 72, and 159. The tumor in patients 3 and 6 regressed significantly, repeatedly in patient 3 over each of four courses of apheresis. Tumor recurred in both patients after cessation of treatment, and they died at days 420 and 79. Patient 5, with inoperable disease, received full-dose radiotherapy immediately following the course of apheresis, and showed complete response in the primary lesion and a major response in the extensive lymph node metastases, dying on day 421 of apparently unrelated causes. Serum IgE in the three patients experiencing tumor regression rose paradoxically during plasmapheresis. Only patient 3 had an elevated level of soluble E-receptor suppressor factor prepheresis; the serum of patient 6 was lymphocytotoxic prepheresis but this activity decreased or disappeared during each of the exchanges studied. Controlled trials are now indicated.

Aged↗
PubMed1982

A solid-phase fluoroimmunoassay for human IgE.

A fluoroimmunoassay (FIA) for the measurement of immunoglobulin E (IgE) is described. The method involves a sandwich technique in which antiserum to human IgE is adsorbed on a cellulose acetate/nitrate disc which is attached to a plastic StiQTM sampler. The prepared sampler is reacted with serum and antigen is bound specifically. After buffer wash and treatment with goat serum to block non-specific binding, the samplers are reacted with monospecific fluorescein conjugated antisera to human IgE. Two buffer washes remove unbound material and the fluorescence which is directly proportional to the IgE concentration is measured in a FIAX fluorometer. Assay standards range from 2 to 400 IU/ml. The method gives within run coefficients of variation (CV) from 3.3 to 8.4% and between run CV from 6.2 to 16.1% being less precise at low analyte concentrations. IgE concentrations of a group of 74 sera determined by FIA using StiQsTM prepared with antisera from 2 sources correlated well with results found by radioimmunoassay.

Animals↗
PubMed1981

Ultrastructural localization of endogenous peroxidase in the lower respiratory tract of the guinea pig.

Endogenous peroxidase activity was demonstrated by cytochemistry in mucous cells of the submucosal glands and tracheobronchial epithelium of guinea pigs. It is localized in the nuclear envelope, in cisternae of rough endoplasmic reticulum, and in secretory granules. It was not seen in Golgi saccules or in the airway lumen. By contrast, all epithelial cells within the lung including mucous (goblet) cells lack activity. Reaction product is also absent from alveolar macrophages and mast cells. The appearance of peroxidase in mucous cells is age-related. No activity was seen at 1.5 ms of age. A few mucous cells were positive at 2.5 and 3 ms while the proportion of positive cells increased substantially up to 7 ms. Thus, the age of guinea pigs in HRP transport studies must receive careful consideration in order to avoid misinterpretation of results. The function of mucous cell peroxidase is unknown. The results of this study suggest that it is secreted. Whether it plays a significant role in lung defense through its well documented anti-infectious properties remains to be determined.

Aging↗
PubMed1980

Two nephelometric methods compared with a radial immunodiffusion method for the measurement of IgG, IgA and IgM.

1. The IgG, IgA and IgM concentrations of a group of 100 or more human sera found by both the rate nephelometric Beckman Immunochemistry System and the endpoint Behring Laser Nephelometer procedure gave good correlations when compared to results obtained by an endpoint radial immunodiffusion method. The correlation coefficients for the Behring method comparisons were 0.958 for IgG, 0.979 for IgA and 0.966 for IgM when only values under 850 IU of IgM/ml were considered. The Beckman system gave correlation coefficients of 0.984 for IgG, 0.993 for IgA and 0.986 for IgM when IgM concentrations were under 500 IU/ml. Determinations from all three methods agreed well except for very high IgM values which were considerably higher by RID. 2. Both nephelometric methods are fast and precise. The average within-run coefficients of variation were 2.6% for the Behring method, 2.2% for the Beckman system and 2.1% for radial immunodiffusion while average between-run precision values of 6.9% for the Behring method, 3.7% for the Beckman system and 4.9% for radial immunodiffusion were found. The Beckman rate system has the advantage of one point calibration, ease of data processing and elimination of sample blanks.

Densitometry↗
PubMed1980

Suppression of anaphylactic reactions in guinea pigs by previous treatment with ragweed aerosol.

Guinea pigs subjected to intranasal dusting with ragweed (RW) pollen or intranasal instillation of RW extract (RWE) showed anaphylactic reactions when subjected to RW extract aerosol (RWE). These animals, however, did not respond to an aerosol of RW whole pollen. Animals which received the RWEA treatment prior to nasal dusting with RW pollen showed no subsequent anaphylactic reactions when exposed to RWEA. Both the aerosol-sensitive and the aerosol-nonresponsive animals exhibited high titers of homocytotropic antibodies to RWE. In addition, the aerosol-nonresponsive animals also had precipitating antibodies of IgG type. The state of nonresponsiveness did not appear to be due to the precipitating antibodies, since this condition could not be passively transferred by sera and blocking antibody activity was not demonstrable.

Administration, Intranasal↗
PubMed1980

Comparison of the PCA titer and aerosol microshock time in guinea pigs made sensitive to ragweed.

Guinea pigs were sensitized either by intranasal dusting with ragweed (RW) pollen or by intranasal instillation of RW extract and subsequently challenged with a RW extract aerosol. It was relatively easy to determine the microshock time for animals which responded between 0 and 10 minutes. Sera from these sensitive guinea pigs were tittered by passive cutaneous anaphylaxis tests. Data from these two assays showed a semilogarithmic relationship with a correlation coefficient of -0.934.

Administration, Intranasal↗
PubMed1978

Two immunofluorescent methods compared with a radial immunodiffusion method for measurement of serum immunoglobulins.

We found high correlations when the values for immunoglobulins G, A, and M, obtained from the analysis of a group of 50 or more human sera by a measured-time radial immunodiffusion method, were compared to values found by two new commercial immunofluorescent methods. The Fiax and the Immuno-Fluor systems make use of fluorescently labeled antibodies and solid-phase immunoadsorbents and offer simple, precise, and objective methods for immunoglobulin quantitation. The Fiax procedure is less time consuming than is the Immuno-Fluor and gives IgG and IgA concentrations that are in close agreement with those found by radial immunodiffusion and IgM values that are significantly lower than the radial immunodiffusion values. The IgG results determined by the Immuno-Fluor method compare well with the radial immunodiffusion results, uhile the IgA values are significantly higher and IgM values significantly lower than those obtained by radial immunodiffusion.

Evaluation Studies as Topic↗
PubMed1978

The topography and age relationship of lipofuscin concentration in the retinal pigment epithelium.

Lipofuscin pigment granules (LPG) have been implicated as a marker of cellular aging. We have quantitated the content of LPG in human retinal pigment epithelium (RPE) as a function of age. Furthermore, topographic distribution of LPG within individual eyes was measured. Microspectrofluorometric determination of the distribution of LPG in human RPE cells revealed a progressive accumulation of LPG with increasing age. LPG first appeared in the basilar portions of RPE cells of young eyes. In older eyes, LPG formed into clumps and were noted to fill the entire RPE cell. The RPE topographic distribution of LPG revealed an increased accumulation in the posterior pole, with a consistent dip at the fovea. The ratio of lipofusion accumulation at the posterior pole, to the total RPE, remained constant throughout life.

Adolescent↗
PubMed1977

The characterization of some of the antigens and allergens in ragweed pollen.

Ragweed extract (RW) and antigens E, K, BPA-R and Ra3 were characterized by electrophoresis on starch and polyacrylamide gels. RW extract and antigen E were also subjected to crossed immunoelectrophoresis. All the antigens contained isomers and contaminating proteins. RW separated by starch gel electrophoresis was skin tested and allergens unrelated to antigens E, BPA-R, Ra3 and K were found.

Allergens↗
PubMed1976

Characterization of some of the enzymes in ragweed pollen.

Ragweed pollen contains 11 esterase, 5 acid phosphatase, 2 alkaline phosphatose, 2 hexokinase, 2 glucose-6-phosphate dehydrogenase isozymes and one leucine amino peptidase band which can be separated by starch gel electrophoresis. The isozymes were distinguished from one another by their electrophoretic mobility, heat inactivation temperatures and antigenic differences.

Acid Phosphatase↗
PubMedDate not supplied

Antigen aerosols induce lung nonresponsiveness.

Guinea pigs intranasally dusted with ragweed pollen (RW) for one month went into anaphylaxis in ragweed extract aerosol (RWEA). Animals which received RWEA pretreatment for one month before nasal dusting with RW pollen were nonresponsive to RWEA. The purpose of this study was to define the mechanism of nonresponsiveness. The protocol for producing either sensitivity or nonresponsiveness was applicable to another antigen, bovine serum albumin (BSA). Antibody blocking passive cutaneous anaphylaxis (PCA) in passively sensitized animals was demonstrable in BSA nonresponder serum. However, the blocking antibody probably was not responsible for the nonresponsiveness because BSA nonresponder serum was also able to sensitize passively the skin and lungs of normal recipients. Also nonresponsiveness was not due to the swallowing of antigen because feeding antigen inhibited synthesis of sensitizing antibody and precipitating antibody both of which were present in high titers in nonresponders. Sensitive guinea pig lungs contained nearly twice as much histamine as normal and nonresponder lungs. However, normal and nonresponders went into anaphylaxis at the same time in an aerosol of compound 48/80. These results suggest that the mechanism of nonresponsiveness produced by pretreatment with antigen aerosols might be due to a modification in antigen reactivity of the lung mast cells rather than to alterations in the mediators of anaphylaxis.

Administration, Intranasal↗