Measurement of human and mouse anti-tetanus antibodies and isotype analysis by ELISA

Status of diphtheria immunity in the Egyptian population

In an attempt to evaluate the levels of immunity against diphtheria in the Egyptian population, 709 healthy subjects aged 2 months-105 years and from six regions of Egypt were investigated. An ELISA was used to determine the serum concentration of anti-diphtheria IgG in each subject. Following widely-used criteria for defining levels of protection, 34.1% of the subjects were categorized as susceptible to diphtheria (with < 0.01 IU antitoxin/ml serum), 43.7% were considered to have basic protection (0.01- < 0.1 IU/ml) and only the other 22.1% appeared fully protected (> or = 0.1 IU/ml). The results revealed that most of the subjects aged 2 months-50 years had a basic or fully protective level of IgG against diphtheria, although males were slightly more likely to be unprotected than females (36.2% v. 31.6%) and certain age-groups appeared to be much more likely to be susceptible than others. If outbreaks of diphtheria like those seen in recent years in the former Soviet Union are to be avoided in Egypt, the most susceptible groups of the population need to be given booster immunizations.

Reduced memory B-cell populations in boys with B-cell dysfunction after bone marrow transplantation for X-linked severe combined immunodeficiency

X-linked severe combined immunodeficiency (XSCID) is a lethal disease resulting in death in infancy. In many instances, haploidentical bone marrow transplantation (BMT) offers reconstitution of T-cell immunity alone, with residual hypogammaglobulinaemia. The exact nature of B-cell dysfunction in these patients is unclear, although differentiation arrest of the B cells is a potential explanation. To ascertain the differentiation status of peripheral blood B lymphocytes from XSCID patients after BMT, the surface expression of CD19, CD10, CD34, CD5, serum immunoglogulin (sIg)M, sIgD, sIgG and CD27 on these B cells was investigated using three-colour flow cytometry. CD27 is a marker of memory B cells. Populations of CD19+IgM-D- B cells, CD19+IgM-only, CD19+IgG+CD27+ and CD19+IgM+ CD27+ B cells were found to be diminished in the XSCID patients after BMT with persistent hypogammaglobulinaemia, compared with both post-BMT patients with B-cell function and age-matched normal controls. This indicated the lack of CD19+IgM-D- B cells, which represent Ig isotype-switched B cells, as well as CD19+IgM-only and CD19+IgG+CD27+ or CD19+IgM+CD27+ memory B-cell populations. Interaction between CD27 and its ligand CD70 has been shown to induce IgG and IgM production by CD27+ B cells. Therefore, the lack of CD27/70 interaction is a probable explanation for the hypogammaglobulinaemia in these patients after BMT.

Trial of immunosuppression in amyotrophic lateral sclerosis using total lymphoid irradiation

Although the cause of amyotrophic lateral sclerosis (ALS) remains unknown, recent studies have suggested an autoimmune mechanism of pathogenesis. Previous trials of immunosuppressive treatment have yielded inconclusive results. Our study was designed to determine whether more powerful and prolonged immunosuppression, produced by total lymphoid irradiation (TLI), would alter the course of ALS. In a double-blind, randomized, placebo-controlled study, 30 patients with classic ALS were treated with TLI, and 31 were given sham radiation. Quantitative measurements of muscle strength, functional motor activity, and humoral and cellular immune status were followed for 2 years, or until death or respirator dependence. Motor function in the TLI-treated and control groups showed no significant differences throughout the study. Overall survival was not significantly different in the TLI-treated and control groups. TLI effectively suppressed cellular and humoral immune function throughout the 2-year study period. Analysis of the relationship between immunosuppression and motor functions showed no consistent effect of treatment. We conclude that powerful and prolonged immunosuppression produced by TLI did not benefit patients with ALS. This fails to support the concept of an autoimmune mechanism of pathogenesis of ALS.

Development of an ELISA for measuring the activity of tetanus toxoid in vaccines and comparison with the toxin neutralization test in mice

An enzyme-linked immunosorbent assay (ELISA) has been developed to measure anti-tetanus toxoid antibody levels in immunized guinea-pig sera as a useful alternative to the currently used toxin neutralization test (TNT) in determining the activity of the tetanus toxoid in vaccines. The ELISA was found to measure antibody levels as low as 5.8 x 10(-5) IU/ml. Furthermore, a comparison of the results from ELISA and TNT involving 132 different commercial vaccines showed a very good correlation (r = 0.94, p < 0.001) between antibody levels measured by both methods. The results suggest that the proposed ELISA is a reliable, simple and economical alternative to the TNT in mice for assessing the activity of tetanus toxoids in vaccines.

Immunosuppression induced by attenuated Salmonella: effect of LPS responsiveness on development of suppression

A live, avirulent strain of Salmonella typhimurium, SL3235, was previously shown to afford protection against virulent Salmonella challenge in three mouse strains of the C3H lineage, C3H/HeJ, C3HeB/FeJ, and C3H/HeNCrlBR, which differ in their innate susceptibility to Salmonella infection, as well as in their responsiveness to lipopolysaccharide (LPS). Concurrent with protection, however, SL3235 was found to induce greater than 90% reduction in proliferative responses of splenocytes from immunized mice to a panel of B and T cell mitogens. Suppression appeared to be independent of susceptibility to Salmonella infection, since the mitogenic responses of hypersusceptible C3H/HeJ and C3HeB/FeJ, as well as resistant C3H/HeNCrlBR mice, were suppressed. The suppressor cell population in immunized C3HeB/FeJ mice was recently shown to be of monocytic lineage. Using transwell plates, co-culture studies indicated that suppression was mediated by soluble factors. In the present study, the effect of LPS responsiveness on susceptibility to SL3235-induced suppression was evaluated in C3H mice by studying their ability to mount plaque-forming cell (PFC) responses to sheep red blood cells (SRBC) and in vivo antibody responses to tetanus toxoid. Comparison of PFC responses as a function of SL3235 dose in C3HeB/FeJ and C3H/HeJ mice, revealed that the latter strain was markedly more resistant to the development of suppression, as evidenced by the significantly higher (10-35-fold) SL3235 doses needed to achieve comparable suppression to those seen in C3HeB/FeJ mice. In contrast to C3HeB/FeJ mice, suppression in C3H/HeJ mice required direct cell-cell contact. In both mouse strains, suppression was alleviated by pre-treatment of immune splenocytes with either mitomycin C or x-irradiation, indicating that actively proliferating cells are required for suppressor function. Resistance of C3H/HeJ mice to SL3235-induced suppression was not due to a lesser bacterial load in vivo, since a higher number of SL3235 organisms were seen in C3H/HeJ spleens compared to C3HeB/FeJ mice. Rather, resistance of C3H/HeJ mice correlated with their reduced ability to recruit macrophages and other inflammatory cells into the spleen, as evidenced by the significantly smaller degree of splenomegaly induced in these mice following immunization with SL3235.

Quantitation of anti-tetanus and anti-diphtheria antibodies by enzymoimmunoassay: methodology and applications

We have developed enzymoimmunoassays (EIA) for the quantitation of antibodies (Ab) to tetanus and diphtheria toxoids (TT, DT) using Immulon I plates coated with the appropriate toxoid. A preparation of human tetanus immunoglobulin with a known concentration of anti-TT Ab was used as calibrator of the anti-TT antibody assay. The assay of anti-DT Ab is calibrated with a pool of human sera whose anti-DT Ab concentration was determined by quantitative immunoelectrophoresis, using a horse anti-DT with known Ab concentration as calibrator. A peroxidase-conjugated anti-human IgG was used in both assays. ABTS was used as substrate, and the reaction was stopped after 1 min incubation with citric acid and the OD measured at 414 nm on a Vmax reader. The assays have been applied to a variety of clinical situations. In patients suspected of having tetanus, the quantitation of antibodies has been helpful in establishing a diagnosis. In patients with a history of hypersensitivity to tetanus toxoid, verification of the levels of anti-TT antibody may prevent unnecessary and potentially harmful immunizations. The assays have also been used for the diagnostic evaluation of the humoral immune response to TT and DT, both in pediatric patients and in immunosuppressed patients. Several non-responders have been detected, and we have recently used the assay to monitor the effects of fish oil administration on the humoral immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

An enzyme-linked immunosorbent assay for the detection of antitetanus toxoid antibody using aluminum-absorbed coating antigen

An enzyme-linked immunosorbent assay (ELISA) for the detection of antitetanus antibodies was developed using aluminum-absorbed tetanus toxoid as the coating antigen. The assay was tested by measuring antitetanus antibody levels in serum obtained from subjects before and after immunization with the aluminum-absorbed tetanus suspension. The specificity of the antibodies for tetanus antigen was tested both before and after antitetanus activity was removed with tetanus antigen-coated beads. Also, the activities of the sera were compared with those of a commercially available test. Our results indicated that the aluminum-absorbed tetanus suspension can be coated onto standard polystyrene ELISA plates and used to measure antibody titers to tetanus toxoid.

Transfer of a functional human immune system to mice with severe combined immunodeficiency

The pressing need for a better experimental system for AIDS research has brought into sharp focus the shortcomings of available animal models and the practical and ethical limitations of studies of immune responses and viral pathogenesis in humans. Current studies of the human immune responses are limited to relatively restrictive in vivo experiments and several in vitro systems that, although useful, allow only short-term studies and support responses to a few antigens. Neither model is particularly amenable to studies of the pathogenesis of diseases of the immune system. We report here that injection of human peripheral blood leukocytes (PBL) can result in the stable long-term reconstitution of a functional human immune system in mice with severe combined immunodeficiency (SCID). Human PBL transplanted to SCID mice increase in number and survive for at least six months; reconstituted mice show spontaneous secretion of human immunoglobulin and a specific human antibody response is induced following immunization with tetanus toxoid. All of the major cell populations present in PBL are found in the lymphoid tissue and blood of SCID recipients, although the relative proportions of B cells, T-cell subsets and monocytes/macrophages in long-term recipients differ from those found in normal PBL and, in mice transplanted with 50 x 10(6) or more PBL from Epstein-Barr virus (EBV)-seropositive donors, EBV-positive B-cell lymphomas often develop. Our results suggest that xenogeneic transplantation of human lymphoid cells into SCID mice may provide a useful model for the study of normal human immune function, the response of the immune system to pathogenic agents and early events in lymphomagensis.

Immunization of mice against tetanus with fragments of tetanus toxin synthesized in Escherichia coli

Two recombinant plasmids, pTet11 and pTet18, which express nontoxic protein fragments of tetanus toxin in Escherichia coli, were constructed. pTet11 protein (86 kilodaltons) is a fusion between part of the E. coli trpE protein and 441 amino acids of tetanus fragment C, and pTet18 (63 kilodaltons) consists of part of fragment B and all of fragment C of tetanus toxin. The synthesis of these proteins was induced in E. coli cultures, and the proteins were partially purified. Mice were immunized with these proteins, and dose-dependent titers of anti-tetanus toxoid antibodies were obtained. The proteins were able to induce neutralizing antibodies in mice, as demonstrated by the ability of mice immunized with 1 microgram or more of protein to survive challenge with 10 50% lethal doses of tetanus toxin.