Zanvil Alexander Cohn (November 16, 1926 – June 28, 1993)[1][2] was a cell biologist and immunologist who upon his death was described by The New York Times as being "in the forefront of current studies of the body's defenses against infection.
"[4] "Dr. Cohn's experiments," reported the Times in his obituary, "threw light on the functions of T-cells, made in the bone marrow, and macrophages, large cells that can surround and digest foreign substances like protozoa and bacteria.
"[3] In a 2009 biographical memoir, Carol L. Moberg and Steinman wrote that "Zanvil Cohn may be most remembered as the founder of modern macrophage biology and for leading the shift in mid-twentieth-century research from bacterial cells to host-parasite relationships.
Cohn's mother, born in the United States of parents from Budapest, was raised in Huntington, Long Island, and worked as a buyer for Oppenheim, Collins & Co., a Manhattan clothing store, later becoming a partner in an apparel firm.
Moberg and Steinman say that he was motivated by Paul de Kruif's book Microbe Hunters and by Sinclair Lewis's novel Arrowsmith, as well as by his experiences with penicillin on the Liberty ships, to become a doctor and medical researcher.
)[5] A 1983 profile of Cohn indicated that "While he was still in medical school, his interest in research had been spurred by a series of technological advances that were dramatically expanding the scope of cell biology.
Cohn's first project in Dubos' lab, which he conducted with Steven Morse, was to confirm that it is polymorph leukocytes that kill the bacteria that cause staph infections.
'"[8] Looking into the genesis of macrophages, Cohn and his colleague Ralph van Furth "used a radiolabeled isotope to label blood monocytes and trace their production and development.
At the same time, electron microscope studies he performed with Hirsch and Martha Fedorko provided further insight into macrophage formation and differentiation.
This work, according to Moberg and Steinman, "illuminated a pivotal pathway to host defense and captivated the minds and spirits of innumerable scientists," resulting in five international conferences on mononuclear phagocytes held at Leiden between 1969 and 1991.
Cohn developed "high expectations that lymphokines and other agents interacting with macrophages would someday enter the physician's armamentarium to fight disease."
At the time of his death, Cohn was arranging "an expanded program to enhance the immune system of immune-compromised individuals with AIDS and tuberculosis.
Cohn also "fostered interactions of young people with physicians at Rockefeller, Weill Cornell Medical College, and Memorial Sloan-Kettering Cancer Center, the three biomedical research and educational institutions across the street from one another," establishing "the Tri-Institutional Biomedical Forum, an informal sherry-and-lecture series reminiscent of his happy 1988 sabbatical at the Dunn School in Oxford, where young scientists could get to know their counterparts at these three institutions."
He also brought new life to the Clinical Scholars program, which trained new doctors "to care for patients on a daily basis while conducting bench research to better understand their diseases.
"Following in the footsteps of retiring editor René Dubos," recalls Moberg and Steinman, Cohn "insisted its pages provide sufficient space to document conclusions adequately and to pursue mechanisms in detail; he looked for papers with novelty, clarity, and a mechanistic analysis that was quantitative, direct, and multifaceted."
"[5] Cohn was elected to the National Academy of Sciences in 1975, was appointed to Rockefeller's first Henry G. Kunkel Professorship in 1986, and received honorary degrees from Bates College (1987), Oxford University (1988), and Rijksuniversiteit in Leiden (1990).
"With an imposing stature and warm demeanor," write Moberg and Steinman, Cohn "exuded an air of equanimity and quiet authority."
"[5] Moberg and Steinman also suggest that Cohn's "talents were distinctive in cell biology and unusual in cellular immunology at the time, because they included an ability to quantify and identify biochemical mechanisms and to obtain images of subcellular behavior."
"[8] Steinman told the New York Times after Cohn's death that "I think his greatest pleasure was to nurture the development of students and young faculty, many of whom now occupy professorial positions.
"[3] Calling him a "demanding yet inspiring mentor," Moberg and Steinman write that Cohn "took great pleasure in nurturing graduate students and postdoctoral fellows," adding that he "never imposed any model or edict that might detract from a person's individuality or creativity.
Gentle, but firm and self-assured, he defined and organized complex research problems into simple, intelligible terms that were rooted in practicality of execution."
Part of his mentoring of graduate students involved going over their first papers, discussing every sentence, removing most punctuation, and smoothing rough data into seamless, well-reasoned arguments."
Then he sat down with sharpened pencils and a yellow lined pad and wrote straight through from beginning to end, without correcting, changing, or rewriting a sentence.
Clad in a white lab coat with a pocket full of pencils and pens, and without any formalities, he arrived quietly, exchanged a few pleasantries about birds, children, or the weather, then inquired about a few experimental details and offered pithy insights or suggestions, and left just as silently.
In turn, this personal attention encouraged special diligence on the part of the researchers who avoided unnecessary work and achieved astonishing progress in the whole laboratory.
Adding that "his unique style enlivened our weekly deliberations," they praised his "incisive manner, his admiration of clever new experiments, his sense of fairness and respect, and his wit.
"[5] A number of films were made to illustrate the processes Cohn studied, including Phagocytosis and Degranulation (with Hirsch, 1962) and Pinocytosis and Granule Formation in Macrophages (1967).
[5] The Journal of Experimental Medicine later noted that Hirsch and Cohn's "elegant films of live phagocytes...remain an ideal component for many courses in biology.
"It was Dr. Steinman's wish during his life," Rockefeller University pointed out, "to honor his mentor and collaborator, Zanvil A. Cohn, with whom he discovered dendritic cells and made scientific discoveries that transformed the field of immunology.