In preparation for a talk I’m giving in September, I searched the The Internet Archive for information about diphtheria antitoxin (AT) production. Though I was really investigating very early AT production (1890s), I couldn’t help but get drawn in by a 1945 Wellcome Physiological Research Laboratories film of diphtheria AT and toxoid production in England. The film is part of the Wellcome Library’s collection on The Internet Archive.
Before World War 2, there was “…no appreciable effort to immunize children to a level that would have materially altered the occurrence of [diphtheria]” (Smallman-Raynor & Cliff, p. 46). However, the Ministry of Health launched a national immunization campaign in late 1940 to attempt to protect children vulnerable to diphtheria in the straitened, crowded war-time conditions. By the end of 1945, about 62% of Welsh and English children had received diphtheria toxoid. Still, as the Wellcome film notes, during the war years, more child deaths resulted from diphtheria than from bombing (9,000 deaths from diphtheria versus 8,000 deaths from bombing).
The 35-minute film goes into exacting detail about AT/toxoid production methods, down to every step of filtration, purification, testing, filling, and bottling. Those interested in the use of animals for medical research and pharmaceutical production should watch it, as the films shows the use of guinea pigs, rabbits, and horses in various stages of production. Additionally, anyone interested in the history of medical and pharmaceutical technology should watch it.
Alexander Glenny (1882-1965) served as consultant on film (he may even be shown in it—it was difficult for me to tell). Glenny was the researcher who, in 1923, used formalin to convert diphtheria toxin to toxoid, developing a compound that was less toxic than the toxin/antitoxin mixtures then in use. And, in 1926, Glenny advanced the practice of using an aluminum compound as an adjuvant in diphtheria toxoid, boosting the immune response to the preparation.
Below are some of the toxoid production steps shown in the film:
- Production of broth to grow the diphtheria bacteria
- Filtration/sterilization of broth
- Incubation of broth with diphtheria bacteria
- Purification, filtration, and buffering of toxin produced
- Testing of potency of toxin on guinea pigs
- Conversion of toxin to toxoid via formalin
Next the film focused on the production of AT in horses – noting that the conditions pictured should be considered “wartime conditions.” Sturdy, good tempered horses older than six years were preferred. Via a test bleeding, lab workers determined if horses had any natural immunity to diphtheria; if so, then the animal would likely be more productive. The horse was given two doses of tetanus toxoid to immunize against that disease (there had been several cases of tetanus in humans treated with tetanus-contaminated diphtheria AT).
The primary course of immunization of the horse was a series of increasing doses of diphtheria toxoid 2-3 times a week, starting with 5 mL of toxoid to an average maximum of 600 mL. Experimental bleedings were made weekly to measure the amount of AT the horse produced. When the AT content was high enough, the horse was bled through the jugular. Workers collected the material in 4L bottles containing an anticlotting agent. A total of 8L of blood could be removed at one time, and this would occur several times over the course of a few weeks. When the horse recovered, it would go through another course of toxoid treatment and then be bled again.
The film then shows in great detail the many steps of AT preparation from the horse serum. I won’t describe them except to note that a primary goal was to reduce horse-specific proteins in the mixture in order to lower the potential for allergic reaction in the AT recipient (you may remember that serum sickness was first described in the context of diphtheria AT treatment).
Currently, no US companies manufacture diphtheria AT, nor is any product licensed by the US FDA. If a US physician is authorized by CDC to use diphtheria AT for treatment, the AT is shipped from a US Public Health Service quarantine station. Its use is governed by this Investigational New Drug protocol. The CDC lists four manufacturers of diphtheria AT, though US supplies are sourced from only one, the Instituto Butantan in Brazil, where 800 horses are used to produce a variety of serum-derived treatments. No cases of diphtheria have been reported in the US since a single case was reported in 2003
CDC. Summary of Notifiable Diseases–United States, 2011. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6053a1.htm
Smallman-Raynor M, Cliff A. Atlas of Epidemic Britain: A Twentieth Century Picture. Oxford: Oxford University Press, 2012.
Relyveld EH. A History of Toxoids. In Plotkin S, ed. History of Vaccine Development. New York: Springer, 2011.