Evaluation of diphtheria convalescent patients to serve as donors for the production of anti-diphtheria immunoglobulin preparations

Aims: The study was conducted to evaluate the possibility of selecting convalescent diphtheria patients to serve in emergency situations as donors for the production of anti-diphtheria immunoglobulin. To select suitable donors, the criterion of an antitoxin titer greater than or equal to3.0 IU/ml was used. In addition, the effects of treatment and the effect of immunization with diphtheria toxoid on the level of anti-diphtheria toxin antibodies were evaluated. Scope: Three groups of diphtheria patients were included in the study. The first group (n = 23) consisted of patients who had a basic antibiotic treatment, with or without serotherapy using horse antitoxin and/or human immunoglobulin. The second group (n = 12) comprised patients examined immediately after the onset of disease. The immunological history of this group was not known. The third group (n = 20) included patients with a known immunization history, treated only with antibiotics but having received a booster immunization with diphtheria toxoid. Antitoxin titers were measured using the toxin binding inhibition (ToBI) assay. Conclusions: In the first group, 47.8% (11/23) of the patients had a diphtheria antibody titer greater than or equal to3.0 IU/ml. For most of them, however, the antibody titers could have resulted from treatment with exogenous antibodies from horse antitoxin or human immunoglobulin (18/23). Only two of the 11 high-titer subjects had received antibiotics only. Among the second group, only two (16.76%) of the patients had an antibody titer of greater than or equal to3.0 IU/ml. In the third group 50% (10/20) of the patients showed an antibody titer of greater than or equal to3.0 IU/ml prior to vaccination, and therefore could be directly considered as donors. Three weeks after booster vaccination, 70% (14/20) had an antibody titer of greater than or equal to3.0 IU/ml and 1 year after booster vaccination, 28.6% (2/7) of the subjects still had titers of greater than or equal to3.0 IU/ml. In 40% of these patients, a decrease was observed 3-4 weeks after the booster dose. It was concluded that convalescent diphtheria patients could be considered as donors in an emergency situation, since approximately half of them showed antitoxin titers of greater than or equal to3.0 IU/ml. (C) 2003 Elsevier Ltd. All rights reserved.