Immunity to tetanus: tetanus antitoxin and anti-BIIb in human sera

Formation and immunological properties of aldehyde-derived protein adducts following alcohol consumption

Most ingested ethanol is eliminated from the body through oxidative metabolism in the liver. Alcohol dehydrogenase is the enzyme that is most important in the oxidation of ethanol to acetaldehyde. However, it has also been demonstrated that cytochrome P4502E1 also can contribute to this process. However, this is not the only aldehyde that is produced after chronic ethanol consumption because oxidative stress and lipid peroxidation can be induced in the liver, which results in the production of malondialdehyde and 4-hydroxy-2-nonenal. These aldehydes are highly reactive and have the ability to react with (adduct) many macromolecules to alter their structure and play a major role in the derangements of hepatic function. Therefore, the formation of these types of adducts in the liver has been proposed as key events leading to the development and/or progression of alcoholic liver disease. In this chapter, methods for the production and detection of these modified proteins will be discussed.

Adduction of soluble proteins with malondialdehyde-acetaldehyde (MAA) induces antibody production and enhances T-cell proliferation

BACKGROUND

The alcohol metabolites malondialdehyde and acetaldehyde can combine to form stable adducts (MAA) which are found in the livers of humans and rats after significant alcohol ingestion. While adducted proteins induce antibody responses in the absence of adjuvants, the mechanisms by which these responses occur are unknown. Thus, it was the purpose of these studies to investigate how MAA modification stimulates antibody and T-cell responses in the absence of adjuvants.

METHODS

Hen egg lysozyme (HEL) was modified with increasing levels of MAA and was used as an immunogen, and antibody and T-cell responses were determined. The role of scavenger receptors in the immunogenicity of MAA-adducted proteins was also investigated.

RESULTS

Maximum antibody response was induced after immunization with 1.8 nM MAA/nM HEL, and was primarily an IgG1 response to HEL as determined by inhibition ELISAs. T-cell proliferative responses after immunization with HEL-MAA were solely to HEL. Immunization with a scavenger receptor ligand in conjunction with HEL-MAA increased the predominant IgG1 response and sharply decreased the IgG2a response by approximately 50%. Binding of HEL-MAA by splenocytes was determined by flow cytometry to be approximately 15% greater than HEL alone, showing a doubling of the geometric mean fluorescence. Also, most of the cells that bound HEL-MAA were class II positive, indicating that antigen-presenting cells can bind the MAA-adducted HEL, and potentially initiate immune responses.

CONCLUSIONS

MAA modification of proteins induces antibody and T-cell proliferative responses in vivo. Initial studies suggest that these responses may be mediated by scavenger receptors that recognize MAA-adducted proteins. This suggests a mechanism by which proteins modified with oxidative products associated with chronic ethanol consumption may alter immune responses that may play an active role in the development and/or progression of alcoholic liver disease.

Method for quantitation of IgG subclass antibodies in mouse serum by enzyme-linked immunosorbent assay

One of the methods for calibration of antigen specific antibodies in a serum involves parallel titration of known concentrations of purified normal immunoglobulins (Igs) and a specific antiserum. We evaluated the effect of three methods for capturing known concentrations of purified normal mouse Igs (IgG, IgG subclasses and IgM) on the anti-tetanus toxoid antibody concentrations assigned to a reference mouse serum: (1) direct coating, (2) capture by pre-coated anti-mouse IgG (Fc) specific antibodies, and (3) capture by pre-coated anti-mouse IgG (Fab) specific antibodies. Direct coating of purified Igs onto plastic was the least efficient and would greatly overestimate antigen specific antibody concentrations. Equivalent concentrations of purified IgG subclasses and IgM produced higher absorbances when captured by anti-Fab antibodies pre-coated on plates than by anti-Fc antibodies. As a consequence, the anti-Fc capture method resulted in the assignment of IgG1, IgG2a and IgG2b tetanus specific antibody concentrations which exceeded the total IgG1, IgG2a and IgG2b concentrations. Additionally, the sum of tetanus specific IgG subclass antibodies exceeded the tetanus specific IgG antibody concentration by > 2-fold. In contrast, the anti-Fab capture method resulted in 2-9-fold lower assigned tetanus antibody concentrations which did not exceed the total Ig concentrations. We conclude that when using enzyme-linked immunosorbent assays, parallel titration of purified normal Ig standards captured by anti-Fab antibodies is superior to anti-Fc capture or direct coating for calibrating antigen specific antibodies in a reference serum.

An alternative to the toxin neutralization assay in mice for the potency testing of the Clostridium tetani, Clostridium septicum, Clostridium novyi type B and Clostridium perfringens type D epsilon components of multivalent sheep vaccines

Potency testing of veterinary vaccines containing clostridial antigens currently requires the vaccination of laboratory rabbits followed by the determination of specific antitoxin concentration in the rabbit sera by toxin neutralization test in mice. ELISAs are described as an alternative method to toxin neutralization for the determination of Clostridium tetani, Clostridium septicum, Clostridium novyi Type B and Clostridium perfringens Type D epsilon antitoxins. The assays were found to be rapid, specific and economical and showed good correlation with the toxin neutralization test.

Detection of tetanus antitoxin using Eu(3+)-labeled anti-human immunoglobulin G monoclonal antibodies in a time-resolved fluorescence immunoassay

Tetanus antitoxin in human sera was detected with solid-phase immunoassays in microtitration modules coated with tetanus toxoid by using Eu(3+)-labeled anti-human monoclonal antibodies on the basis of an exactly calibrated antibody standard. The use of a time-resolved fluorescence immunoassay (TR-FIA) significantly improved the quantitative detection of tetanus antitoxin over that of the enzyme-linked immunosorbent assay (ELISA) technique because of its high sensitivity and its wide measurement range, detecting antibody levels between 0.001 and 12.5 IU/ml with a single serum dilution of 1:100. For the same purpose, two different serum dilutions (1:100 and 1:1,000) were needed in the ELISA technique. TR-FIA is reproducible and can be performed in 3.5 h. A study of 2,630 serum samples was undertaken to examine the age-dependent distribution of titer levels, indicating the decline of sufficient protection in patients older than 60 years. The wide measurement range of TR-FIA enabled fast examination of large numbers of serum samples without the need for repetition, with further sample dilution, as was often necessary in the ELISA procedure.

Combined estimation of tetanus and diphtheria antitoxin in human sera by the in vitro Toxin-Binding Inhibition (ToBI) test

The use of the principle of inhibition of toxin binding to an antitoxin coated immunoassay plate as described in a previous paper for tetanus antitoxin titration, was adapted for the estimation of diphtheria antitoxin in human sera. With a few modifications, a Toxin-Binding Inhibition (ToBI) test was developed which could be used for a combined estimation of both tetanus and diphtheria antitoxin levels. The application of streptavidin-biotinylated peroxidase complex when using small serum samples (less than 50 microliters) is discussed. Antitoxin titres (both diphtheria and tetanus) of 0.002 IU ml-1 were detectable by the ToBI test, this being far below the level considered to be protective in man. Sera from 140 adults with different vaccination histories were titrated for both tetanus and diphtheria antitoxin. Good correlations were found between the estimates obtained by the ToBI test and those obtained by the toxin-neutralization (TN) test in mice (tetanus antitoxin) and those obtained in the in vitro neutralization test in VERO cells (diphtheria antitoxin). It is concluded that the ToBI test is a simple and reliable alternative to the functional models currently in use for the estimation of diphtheria and tetanus antitoxin levels. In addition, the ToBI test eliminates the need for laboratory-animal or cell-culture facilities and can be performed with small quantities of serum as required in field trials.

The toxin binding inhibition test as a reliable in vitro alternative to the toxin neutralization test in mice for the estimation of tetanus antitoxin in human sera

A method for the screening of human sera for tetanus antibodies has been developed and evaluated. The toxin binding inhibition test (ToBI-test) is based on inhibition of the binding of tetanus toxin to an antitoxin-coated immunoassay microtitre plate by tetanus antibodies. Serum samples from 191 healthy adults with different vaccination histories have been titrated for tetanus antibodies by the toxin neutralization (TN) test in mice, by toxoid-ELISA and by the ToBI-test. In every respect, the ToBI-test proved to be the best in vitro alternative to the TN-test in mice. Comparisons showed a higher degree of correlation between the ToBI-test and the TN-test than between the toxoid-ELISA and the TN-test. Furthermore, no overestimation of antibody content was seen in titrating low titre sera by the ToBI-test. In contrast, several false positive results were seen when using the toxoid-ELISA. It is concluded that the ToBI-test is a reliable and precise alternative to the TN-test and can be performed under simple laboratory conditions in a short time.