Allan William Cripps: a mucosal immunologist and mentor from beginning to end

Allan Cripps was internationally recognized in the field of mucosal immunology, in particular the relationship between respiratory diseases and mucosal immunization strategies. Allan's career spanned scientific and applied research, commercialization, health education, and evolved into leadership roles in public‐health and academic administration. Allan published over 400 papers and mentored over 40 research higher degree candidates. Allan was renowned for his mentorship, that did not end with the awarding of a PhD or Master's degree, but continued across a lifetime of professional engagement. Allan's key contributions to immunology included characterizing the ontogeny of the human mucosal immune system, understanding the impact of respiratory infections and otitis media in children, developing diagnostic technologies and mucosal vaccine strategies, and identifying the roles of the common mucosal immune system in human health. In this biography for the 100th anniversary of the Journal, we follow his journey of discovery and contributions to immunological research.

Immunology & Cell Biology 2023; 101: 916-920; doi: 10.1111/imcb.12706 Allan Cripps (1950-2022).Allan was at the forefront of the discovery of the common mucosal immune system.He was internationally recognized for his expertise in the field of human mucosal immunology, with specialization in respiratory diseases and mucosal immunization strategies.Allan's career in mucosal immunology was fortuitous, as he could very well have taken different pathways into medicine, agriculture or veterinary science.As Allan described himself, 1 he was "a country boy from a farming family in northern New South Wales".His passion for research was ignited when he undertook an undergraduate Honors degree in Physiology at the University of New England in Armidale (Figure 1).
Allan's introduction to mucosal immunology was through his PhD with Professor Alick Lascelles, a veterinarian at the University of Sydney, although the PhD program was in sheep.Alick Lascelles and Professor Bede Morris, at the Australian National University in Canberra, had developed surgical techniques used by Allan to study the origin of immunoglobulins in mucosal secretions in sheep.Allan's PhD program established that all ovine IgA in intestinal secretions, 2 saliva 3 and milk 4 was locally produced at the mucosal site.
Instead of continuing a proposed post-doctoral research career with Bede Morris in Canberra, Allan joined the Flinders Medical Centre in Adelaide in 1976 as a hospital scientist.It was here his research in human mucosal immunology had its genesis with Dr Andrew Kemp, who was analyzing immunoglobulins in saliva from infants. 5 In 1978, Allan accepted a position from Professor Robert Clancy as the Scientific Director of a new diagnostic immunology service at Royal Newcastle Hospital that also included establishing a mucosal immunology research unit in the new Faculty of Medicine at the University of Newcastle. 6The clinical and research collaborations established through the new Hunter Immunology Unit, particularly after a visit to Mike Alpers in Papua New Guinea (PNG), were the basis of Allan's long-term research passion to characterizing the human mucosal immune system and a commitment to developing mucosal immunization strategies to prevent bacterial respiratory infections and otitis media in children.
Allan Cripps and Robert Clancy were Maree Gleeson's PhD supervisors and guided the establishment of a comprehensive longitudinal study of the development of mucosal immunity in infants and children.The study followed infants from the day they were born to 5 years of age and established the patterns of ontogeny of oral mucosal immunity in children. 7,8The key findings over the next 21 years of follow up studies identified: the molecular characteristics of IgA 9 and a rare study of IgD 10 in infant saliva; the impact of infant feeding practices on mucosal immunity; 11 the influence of respiratory infections and the subsequent development of allergy and asthma; 12,13 and the role of hyperimmune mucosal responses following a respiratory infection in sudden infant death syndrome. 14,15he findings laid the basis for understanding how the human mucosal immune system developed and informed the strategies for mucosal immunization against bacterial respiratory infections and otitis media in children and adults.
The mucosal immunology research initiated and led by Allan Cripps and Robert Clancy in Newcastle, continued over the next four decades.
The research included parallel studies in humans and animal models and led to the development of a multitude of scientific technologies and surgical techniques, and clinical trials that identified vaccine candidates and immunization strategies.All with a focus on the diagnosis and prevention of bacterial infections and diseases at mucosal sites.The studies investigated mucosal immunity in humans not only in the gut and respiratory tract 16 but initiated leading immunological research on other mucosal sites, including infections in the eye, 17 ears, 18 and dental diseases of the oral cavity, 19 again all focused on disease prevention and the potential for developing mucosal vaccines.Two further longitudinal studies in children examined the impact of pre-school and respiratory infections on the ontogeny profile, 20 and the association of mucosal immune competence and bacterial colonization to otitis media in indigenous children. 21The association with Mike Alpers in PNG was also long lasting 22 in addressing pneumonia in children.
Allan's interest in veterinary research also continued, while in Newcastle, with the prospect of developing animal vaccines, predominantly in sheep [23][24][25] and later in horses. 26espite moving into significant and demanding academic leadership roles, first at the University of Canberra in 1994 and then at Griffith University in 2003, Allan continued an active research career.The infections investigated by Allan's research teams targeted major pathogens involved in respiratory diseases and otitis media in children and chronic bronchitis in adults. 27Haemophilus influenzae [28][29][30] and Pseudomonas aeruginosa, [31][32][33] were the main respiratory targets but research also included Moraxella catarrhalis, 34 Streptococcus pneumoniae 35 and gut pathogens such as Helicobacter pylori. 36Allan's mucosal immunology research spanned basic scientific discoveries in technology and vaccinology, resulting in Allan being a co-inventor of over 30 patents that identified novel vaccine candidates for respiratory pathogens and the development of diagnostic technologies.
While at the University of Canberra, a research collaboration between the University of Newcastle and the Australian Institute of Sport (AIS) examining the mucosal immune function of elite athletes and their susceptibility to respiratory infections 37 was expanded to assess gut microbiome-immune interactions.Allan had been at the forefront of research into the impact of the gut microbiome on immunity at other mucosal sites and had developed technologies, with Dr Henry Butt, to identify the respiratory and gut microbiome. 38,39This early research had led to clinical trials of several commercial probiotics and collaborations with biotechnology companies in the development phases of new probiotics to alter the gut microbiome.1][42] These studies investigated changes in the gut microbiome and metabolites, systemic and mucosal immunity and illness patterns over periods of intensified training periods in well-trained athletes.These are considered pioneering studies for probiotics, resistant starch and synbiotics and have provided key recommendations on the use of these supplements in healthy well-trained individuals and elite athletes. 43,44llan's focus on mucosal immunity and the microbiome continued at Griffith University from 2009 to 2022, with a series of human based trials in elite athletes, 45,46 allergy and atopy, 47 chronic inflammation in obesity 48 and infectious disease; taking a leading role in an international consortium of research on SARS-CoV-2. 49n addition to establishing the new medical and dental schools at Griffith University and the Gold Coast University Hospital, Allan has left a legacy of a vibrant mucosal immunology research unit at Griffith University.
Allan served on many international and national health, research, biotech company and academic committees, councils, boards and conferences.In recognition of his services to research, education and health, Allan was awarded an Officer in the Order of Australia in 2015.
We celebrate in this ICB-centenary article an individual whose professional and personal approaches had a broad, far reaching and inspirational impact on colleagues and students.Those who knew Allan well know he was quiet, unassuming, always ready to listen and help and had a keen intellect, not just on immunology but on life's important issues.Often these things were discussed over a great bottle of red wine.To conclude with Allan's own words 1
J Sci Med Sport 2017; 20: e81.47.Tong PL, West NP, Cox AJ, et al. 2023 The Authors.Immunology & Cell Biology published by John Wiley & Sons Australia, Ltd on behalf of the Australian and New Zealand Society for Immunology, Inc.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. ª