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Immunology: Then and Now

Art by Jake Upton

By Marlena Tyldesley

My first introduction to white blood cells was at around 10 years old when, hoping to distract my doctor from ever actually drawing my blood, I asked what we were looking for. He explained that there were little worker cells in my body fighting sickness and we needed to find them, successfully stumping me enough that he was able to stick me with the needle. I have become increasingly fascinated with immunology ever since, and it is the topic that drew me into molecular biology. What follows is a (very) brief history of immunology as a field of study and medicine written by Stefan Kauffman.

In the 19th century, Louis Pasteur’s and Robert Koch’s work on the origins of disease laid the groundwork for the birth of immunology as a field of study. Elias Metchnikoff, according to author Stefan Kaufmann, then made the first major discovery of the field of immunology: phagocytosis. Phagocytosis is the process by which cells engulf foreign threats to the host, like bacteria, and founded our understanding of the innate immunity branch of immunology (the branch concerning immunity inherent to our bodies, our first line of defense against invading foreign objects).

Closing out the 19th century, Emil Behring and Paul Erlich made the second big discovery of immunology: antibodies. Antibodies are super-sticky particles in serum that have antimicrobial activity specific to a certain pathogen. Behring harnessed the power of these proteins to create serum therapy, in which serum from someone previously infected with, say, tetanus, could be used to treat another person sick with the toxin. Erlich extrapolated from serum therapy that antigens (like the toxins in tetanus) actually spurred the production of these antibodies, among a myriad of other immunologic concepts that he is now famous for. This concept of antibodies is the foundation of our understanding of the second branch of immunology, acquired immunity, in which we develop defenses against diseases as we are exposed to them.

The 20th century is marked by discoveries in immunochemistry, most notably the determination of the chemical structure of antibodies by Rodney Porter and Gerald Edelman. Karl Landsteiner, having already worked to explain how antibodies are recognized, furthered his research to found the ABO major blood group system we use today.

In the second half of the 20th century, the focus of immunology shifted from chemistry to biology, with a ton of research on the MHC, or Major Histocompatibility Complex. The MHC is a system by which cells recognize “self” (typical of the host organism) or “non-self” (a foreign invader of the host organism) proteins and respond accordingly. This period also included even more research on antibodies and the discovery of lymphocytes (the cells that interact with antibodies and govern our immune responses) and antigen-presenting cells (involved in the transportation of antibodies to lymphocytes).

Most notably, in the time of COVID, a modern discovery of immunology is monoclonal antibodies. These antibodies are grown in a lab from fusing an antibody-producing cell , chosen specifically for its antibacterial or antiviral activities against a disease of interest, with a tumor cell, giving a seemingly endless supply of the exact same antibody. They have been used as a treatment for people infected with COVID, as well as a cancer therapy.

Below is a figure from the article representing the evolution of our understanding of the two branches of immunity.

(Kauffman, 2019)

Immunology is a critically important field of study as our understanding of medicine grows. Especially now, given the toll we have seen diseases like AIDS, Ebola and now COVID take on entire communities and even countries, our ability to understand our lines of defense against disease is absolutely crucial.


Kauffman, S. (2019). Immunology's Coming of Age. Frontiers in Immunology, 10(684).

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