University of Otago Wellington, Wellington, New Zealand
|Charles Harrison Blackley|
Since the 1950s, and especially since the 1980s, there has been a worldwide increase in the prevalence of allergic diseases, asthma, hay fever, and eczema. In the last twenty years the most notable manifestation of this trend has been the rapid rise in food allergy in children.1 Thirty years ago food allergy was uncommon; now certain foods are often banned from schools and aeroplanes, such is the frequency of this condition. We are living in highly allergic times, but, despite an enormous amount of medical literature, we still have no idea why this has happened. There are a few clues, some suggested more than 140 years ago by one of the founding fathers of modern allergy: Charles Harrison Blackley (1820-1900).
Blackley was born in 1820 in the shadow of Blake's dark satanic mills in Bolton, Lancashire. Following his father's death he moved to Manchester with his mother. He was apprenticed to the engravers Bradshaw and Blacklock and established his own engraving business in 1844. The engraving business was no more than a means to an end and in 1855, after attending various adult education institutions, he entered the Pine Street private medical school in Manchester. He graduated three years later and immediately established a medical practice in Hulme, Manchester. But even this medical education and practice appears to have been no more than a further means to an end. His real passion was the study of his own Catarrhus Aestivus, or summer cold, now commonly known as hay fever, from which he suffered seriously.
The condition was first described by John Bostock in 1819, in himself.2 Over the next decade Bostock found a further twenty-nine cases. Interestingly, nearly all of the cases he observed occurred in members of higher social classes, including royalty and the nobility. The cause was unknown and scientists suggested many theories such as ozone and benzoic acid (both could irritate the nasal mucosa), various odours, dust, and the heat from summer itself.
Blackley's first contribution was to show unequivocally and in painstaking detail that various pollens, especially grass pollens, caused all the symptoms of hay fever when applied to his own eyes and nose. By means of serial dilutions he showed that just under 2µg of pollen would elicit symptoms and 20µg applied every 24 hours would maintain a severe attack of hay fever.3 Blackley invented allergy skin testing, applying pollens to his own abraded skin which produced wheals with diameters measured in inches and standing ¾ inch above the skin.4 He observed the fine structure of pollens and the granular material contained within pollen grains.
Blackley also observed the recently described Brownian motion (1827) of pollen in a water suspension. He then proceeded to study the ebb and flow of his own symptoms in relation to his whereabouts, the season, and wind direction. He was the first to make a systematic pollen count showing that airborne pollens peaked in late June and were all but over by the end of July. He kept meticulous records of his own symptoms and was able to relate these to his daily pollen counts. He became convinced that pollen travels large distances on the wind.
In order to measure pollen in the air, Blackley built devices that would expose microscope slides using a timer and flew these beneath kites reaching elevations of 2,000 feet. He would occasionally fly two kites in tandem, one collecting pollen at a lower level, the other hundreds of feet above.4 These kites, he discovered, would have different amounts of pollen and wind directions could be very different at different levels. From these experiments, Blackley learned that pollen could be carried many miles on air currents. Charles Darwin had noted that dust could be carried far out to sea on wind currents. Darwin's observation suggested to Blackley that the reports of attacks of hay fever that occurred on ships at sea might still be explained by pollens carried by the wind, and they corresponded on these issues.
Although Blackley successfully determined that pollens were a major cause of hay fever, his attempts to find effective treatments were largely unsuccessful. He recognised that avoidance worked and if one could entirely avoid pollens one could avoid the symptoms. He experimented with filtration systems with some effect, but these were difficult to implement, especially given the very small quantities required to cause symptoms. The potency of pollens led him to develop an interest and belief in homeopathy. He joined the British Homeopathic Society and became editor of the Manchester Homeopathic Observer. There is no record that homeopathic remedies ever helped him.
Blackley was a one-man walking allergy laboratory. He identified pollens as a major cause of his hay fever symptoms and showed that very small amounts could elicit symptoms. He measured pollen counts in the ambient air and showed that they could travel long distances at high altitude. Of course what he could not do was elucidate the underlying mechanisms by which pollens led to the inflammation and edema associated with hay fever. It would be almost 100 years before those mechanisms would be understood.5 It is perhaps not surprising that he was unable to find an effective treatment as none exists to this day. It was not until the 1970s that intranasal corticosteroids were shown to suppress the inflammation caused by pollens, though even this treatment is effective only when used continually.
But perhaps it is not just for this meticulous measurement from a self-made Victorian physician-scientist that we should remember and revere Charles Blackley, for he also thought about hay fever with great insight. Having demonstrated grass pollens as a major cause, he headed to the surrounding farming community where he expected to find plenty of cases, but found virtually none.
One very curious circumstance in connection with hay fever is that the persons who are most subjected to the action of pollen belong to a class which furnishes the fewest cases of the disorder, namely, the farming class. This remarkable fact may be accounted for in two different ways: it may, on the one hand, be due to the absence of the predisposition which mental culture generates; or, on the other hand, it may be that in this disease there is a possibility of a patient being rendered insusceptible to the action of pollens by continued exposure to its influence.4
Blackley's nuanced observation, available to us through his technical writing, remains with us today. For "mental culture," we might substitute "higher socioeconomic circumstances," as allergic disease is more prevalent in economically developed societies.6 Or, perhaps, "increasingly hygienic lifestyles," a hypothesis that suggests too much hygiene has subverted the immune system by directing it towards allergy and away from fighting infectious disease.7 Indeed, being raised in a farming environment has been shown to be strongly protective for allergic diseases.8 For "being rendered insusceptible by excessive exposure" we might substitute "tolerance," a central concept for the use of desensitizing immunotherapy and one that developed directly from Blackley's observations. One hypothesis for the very recent rise in the prevalence of food allergy is that the advice given to mothers to avoid allergenic foods such as peanut and egg in early infancy is the very cause of food allergy.9 According to this theory, early introduction of large amounts of oral peanut or egg helps infants gain an immunological tolerance to these allergens, much like the Manchester farmers and hay fever.
I can't help but think that if Charles Blackley could return today he would be surprised to learn that his original observations still guide thought about the origins of allergic disease. But equally, I can't help but think that once he had caught up with the intervening 145 years of allergic literature, he would be even more amazed that we are still so far from a detailed understanding of these goings-on and that an effective permanent treatment or prevention strategy is nowhere in sight. We are in serious need of Charles Harrison Blackley II.
I have drawn on the excellent short biography of Charles Blackley by Geoffrey Taylor and Jane Walker published in 1973, to mark the centenary of his landmark book.10
1. Osborne NJ, Koplin JJ, Martin PE, Gurrin LC, Lowe AJ, Matheson MC, Ponsonby AL, Wake M, Tang MLK, Dharmage SC. Prevalence of challenge-proven IgE-mediated food allergy using population-based sampling and predetermined challenge criteria in infants. JACI. 2011;127(3):668-76. e2.
2. Bostock J. Case of a periodical affection of the eyes and chest. Medico-Chirurgical Transactions. 1819;x(i):161-5.
3. Blackley C. Hay Fever its Causes, Treatment and Effective Prevention. London: Balliere, Tindall & Cox; 1880.
4. Blackley C. Experimental researches on the causes and nature of catarrhus aestivus. London: Balliere, Tindall & Cox; 1873.
5. Bennich H, Ishizaka K, Johansson S, Rowe D, Stanworth D, Stanworth W. Immunoglobulin E, a new class of human immunoglobulin. Bull World Health Organ. 1968;38(151-2).
6. ISAAC Steering Committee. Worldwide variations in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema: The International Study of Asthma and Allergies in Childhood (ISAAC). Lancet. 1998;351:1225-32.
7. Strachan DP. Family size, infection and atopy: the first decade of the "hygiene hypothesis". Thorax. 2000;55 Suppl 1:S2-10.
8. Riedler J, Braun-Fahrlander C, Eder W, Schreuer M, Waser M, Maisch S, Carr D, Schierl R, Nowak D, von Mutius E. Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey. Lancet. 2001;358(9288):1129-33.
9. Prescott SL, Smith P, Tang M, Palmer DJ, Sinn J, Huntley SJ, Cormack B, Heine RG, Gibson RA, Makrides M. The importance of early complementary feeding in the development of oral tolerance: concerns and controversies. Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology. 2008 Aug;19(5):375-80.
10. Taylor G, Walker J. Charles Harrison Blackley, 1820-1900. Clinical allergy. 1973 Jun;3(2):103-8.
JULIAN CRANE, MB BS FRCP is a research professor in the Department of Medicine at the University of Otago Wellington. Professor Crane's main research interests are allergic disease: epidemiology, prevention and treatment. Professor Crane also studies history and the history of medicine.