A new solid-phase radioimmunoassay to measure IgG secreted by cultured human lymphocytes

Amyotrophic lateral sclerosis: Part 2. Etiopathogenesis

The pathogenesis of the motor neuronal degeneration in amyotrophic lateral sclerosis (ALS) is unclear, though several possible etiological factors are currently being investigated. A unifying hypothesis will have to explain the diverse geographical occurrence, clinical features, and selective vulnerability and relative resistance of different neuronal populations in the disease. It is possible that different biochemical defects underlie this diversity, or alternatively that the many factors incriminated in the etiology may act upon an underlying genetic-biochemical abnormality to trigger premature neuronal death. Viruses, metals, endogenous toxins, immune dysfunction, endocrine abnormalities, impaired DNA repair, altered axonal transport, and trauma have all been etiologically linked with ALS, but convincing research evidence of a causative role for any of these factors is yet to be demonstrated.

Synthesis of human immunoglobulins in vitro: comparison of two assays of secreted immunoglobulin

One consequence of B-lymphocyte activation is immunoglobulin production, which can be quantitated by various techniques. We have compared assay of plaque forming cell (PFC) and determination of immunoglobulins by ELISA in culture supernatants of human lymphocytes stimulated with pokeweed mitogen and with Staphylococcus aureus. These assays correlated well (r greater than 0.77) in all major immunoglobulin classes studied. The close correlation suggests that determination of secreted immunoglobulins by ELISA may be substituted for the PFC assay.

Chemiluminescent immunosorbent assay of serum myoglobin based on the luminol reaction

A simple and sensitive method for the determination of serum myoglobin is described. Myoglobin was determined in the range of 10-500 micrograms/1 by the chemiluminescent luminol reaction after adsorption to anti-myoglobin IgG onto a solid phase. Only 50 microliter of serum has to be used and the luminescent immunoassay (LIA) has a better sensitivity and a wider linear range than the conventional radioimmunoassay (RIA). However, in its present form LIA has a higher imprecision than RIA. In clinical specimens the correlation between the two methods was excellent.

Immunochemical characterization of the androgen-dependent spermine-binding protein of the rat ventral prostate

A solid-phase radioimmunoassay was developed to measure the level of the androgen-dependent spermine-binding protein (SBP) in the cytosol fraction of the rat ventral prostate during endocrine manipulation. The concentration of SBP and immunologically cross-reacting material (CRM) in the ventral prostate was at least 5000 times higher than the level of CRM detected in rat serum or cytosol from other rat tissues. Cytosol from the ventral prostate of intact rats was separated by DEAE-cellulose chromatography into three major fractions of CRM. One of these fractions corresponded to the elution position of SBP. Cytosol prepared from rats 48 h after castration lacked SBP and one of the two other fractions of CRM. This loss coincided with an increase in CRM in the remaining fraction. No significant difference was detected in the total level of CRM when intact and 48 h-castrated rats were compared. Injection of rats with 5 alpha-dihydrotestosterone (DHT) immediately after castration prevented these changes in the profile of CRM. Several proteins cross-reacting with antibodies to purified SBP were detected in cytosol by using an immunoblot procedure. The highest-Mr band corresponded to SBP. The effect of short- and long-term castration and subsequent DHT treatment on CRM was studied by using the immunoblot technique. Short-term castration (2 days) led to the disappearance of CRM coinciding with SBP (Mr 35 000-38 000) and an increase in smaller forms of CRM (Mr 24 000 and 22 000). Injection of rats with DHT 2 days after castration led to the reappearance of CRM corresponding to SBP, which returned to normal levels within 4 to 5 days of treatment. Long-term castration (up to 14 days) led to a gradual disappearance of all CRM; subsequent DHT treatment led to the reappearance of all forms of CRM and normal levels were attained within 5 days. We have identified SBP and the various forms of CRM as a secretory product of the rat ventral prostate by immunohistochemical staining and by DEAE-cellulose fractionation of prostatic fluid. Prostatic fluid is rich in proteolytic activity and these proteinases may be responsible for processing SBP to small forms of CRM.

Mechanisms responsible for reduced in vitro immunoglobulin secretion in aged humans

Age-related changes in the processes involved in T cell dependent polyclonal B cell activation in man were studied by comparing immunoglobulin (Ig) produced in autologous T:B (E+:E-) cell cultures of young and old donor pairs with Ig produced in crossover cultures. Each young and old donor was classified as a responder or a non-responder based on Ig levels in autologous pokeweed mitogen-activated T:B cultures. The data indicate that: (1) T suppressor influences are a major determinant of non-response in the young; (2) T cells of nonresponder old donors can support high levels of Ig secretion by young donors' B cells; (3) low response to pokeweed mitogen stimulation in the elderly may reflect either direct refractoriness of B cells to T cell dependent stimulation, heightened B cell sensitivity to suppressor signals, or a combination of the two.

Studies of immunoglobulin synthesis in cultures of peripheral T and B lymphocytes: reduced T-suppressor cell activity in Graves' disease

Cellular interactions involved in Graves’disease were studied in patients in different stages of the disease and in normal controls. Synthesis and secretion of immunoglobulin G (IgG) in the supernate of pokeweed mitogen (PWM)‐stimulated cultures of constant numbers of non E rosette forming cells (E− cells) and of increasing numbers of autologous E rosette forming cells (E+ cells) (E+/E− ratios = 1:1, 2:1, 4:1, 8:1, 10:1) were measured by a specific solid‐phase radioimmunoassay. In the normal group, the mean IgG production increased with increasing E+/E‐ ratio (T helper effect), reaching a maximum at a T/B ratio of 4:1, then decreased at higher E+/E− ratios (T suppressor effect). At a E+/E− ratio of 10:1 the IgG synthesis was 39% of the peak value. In the Graves’patients the mean IgG synthesis increased with increasing numbers of E+ cells at every ratio with a peak value found at E+/E− ratio = 10:1. There was no detectable suppressor effect. In three experiments performed with allogeneic combinations of cells, it was observed that the Graves’E− cells were able to respond both to helper and suppressor signals from normal E+ cells, while the Graves’E+ were not able to suppress IgG synthesis by normal E− cells. Treatment of E+ cells with 3,000 cGy of irradiation before adding them to E− cells abolished the suppressor effect seen at the higher E+/E− ratios in the normal controls because of inactivation of the T suppressor lymphocytes. In contrast, the same procedure was without effect on the IgG synthesis by E− cells in Graves’patients. When peripheral blood mononuclear cells (PBMC) were cultured in the presence of PWM and of PWM + Concanavalin‐A (Con‐A), the PWM‐induced synthesis of IgG was suppressed in the presence of Con‐A by 75% (using unfractionated PBMC) and 74% (using E+/E− cells) at 1:1 ratio in normal controls, while Graves’patients’cells caused lower suppression of 66 and 48%, respectively. This latter value was significantly different from that found in the normal group (P < 0·05).

A modified radio-immune antiglobulin test for the screening of anti-red blood cell antibodies in hybridoma supernatants

A radio-immune antiglobulin test was developed using mouse monoclonal anti-human A red blood cell (RBC) antibodies, and applied to the screening and study of hybridoma supernatants containing anti-human RBC antibodies. The latter antibodies were provided either as known monoclonal antibodies from culture supernatants and ascitic fluids, or as culture supernatants to be screened. The technical feasibility of the test was greatly facilitated by the use of remova-well disposable polystyrene plates, multichannel pipettes, and multiple-plate centrifuge holders. The sensitivity of the test and its relevance for the screening of hybridoma anti-human RBC antibodies is discussed.

Light chain composition of CSF oligoclonal IgG bands in multiple sclerosis and subacute sclerosing panencephalitis

The light chain composition of MS and SSPE CSF oligoclonal IgG bands was examined using isoelectric focusing and a sensitive peroxidase-antiperoxidase (PAP) staining technique specific for gamma heavy chains (gamma), kappa light chains (k), or lambda light chains (lambda) and a radioimmunoassay (RIA) for gamma, k or lambda. Many bands in the 7 MS and 4SSPE CSF examined were monoclonal, staining for either IgG-k or IgG-lambda. By staining, all MS CSF were k predominant; SSPE CSF were variously k or lambda predominant. RIA confirmed the k predominance of MS CSF. Three MS and 2 SSPE CSF contained bands staining for lambda alone, i.e. free light chains. Analysis of RIA data confirmed these findings in 2 MS cases. The difference in light chain predominance of MS and SSPE CSF may reflect differences in the antigenic target, or the age of patient at the time when band-synthesizing clones are triggered. Six of 7 MS and all 4 SSPE CSF contained oligoclonal bands staining for gamma and for both kappa and lambda, probably representing artifacts of IEF. No predominant immunochemical differences between bands in MS and SSPE were detected.

A rapid miniaturized solid-phase radioimmunoassay technique for secreted immunoglobulins, employing microtiter plates, antibody bound to polyacrylamide beads, and filter strip harvesting

We have developed a solid-phase radioimmunoassay technique, which allows a large number of samples to be assayed, while minimizing amounts of reagents and technician time. The assay is run in microtiter plates, which results in improved organization, shorter assay set-up time and advantageous miniaturization. On the first day only 3 reagents are required: sample or standard, a 125I-labeled antigen, and an antibody attached to a polyacrylamide bead. After on overnight incubation period, the assay is harvested using a commercial microharvesting apparatus (24 samples/2 min) and placed directly into a gamma counter for counting. In the present study, we have developed the assay to measure secreted IgG, IgM and IgA, and we have compared our results with those of a standard radioimmunoassay technique. This rapid, simple, economical approach should be applicable to the radioimmunoassay of other substances as well.

Influence of azathioprine (imuran) on in vitro immune function in multiple sclerosis

In vitro immune function was assessed in patients with multiple sclerosis (MS) who were receiving Imuran therapy, in untreated MS patients, and in controls. In untreated stable MS patients, concanavalin A (Con A)-driven mitogenic reactivity (T effector function) and Con A-induced suppressor activity were modestly reduced compared to controls; pokeweed mitogen-induced immunoglobulin G (IgG) secretion was increased. Untreated patients with active MS demonstrated high levels of IgG secretion and marked decreases in suppressor activity. In Imuran-treated patients, Con A mitogenic responses and suppressor activity were comparable to those observed in untreated stable patients, and IgG secretion was reduced. The results in the treated patients likely reflect a direct effect of Imuran on B cell function rather than an indirect effect mediated via suppressor cells.

Development of solid-phase immunoassay using chemiluminescent IgG conjugates

Solid-phase luminescent immunoassay (LIA) was studied using mainly aminobutyl-ethylisoluminol-IgG conjugates. Different solid-phase supports such as immunobeads, polystyrene balls and tubes gave comparable results although tubes were preferred in most of the assays because of the better linearity and reproducibility obtained and their ease of handling. The properties of the conjugates were tested using both direct and sandwich LIA. Direct LIAs performed using sheep-anti-rabbit IgG coated balls provided information on the antigenicity of the conjugates while the sandwich LIA was the actual working system. A sensitivity of 1 ng was obtained in this system. The stability, easy use, safe handling and low cost of the conjugates coupled with a short assay time make this luminescent system a potential alternative to RIA.