Why do women have stronger immune systems than men? A $1 million grant from the W.M. Keck Foundation to Tulane University will contribute to a study seeking to answer that very question. Do women have an extra line of defense in their immune systems that gives them an advantage over men in fighting infections? The team in Louisiana hopes to answer this question and more.
The grant was awarded to a team of researchers at the Tulane University School of Medicine led by James McLachlan, PhD, associate professor of Microbiology and Immunology. Part of a familiar team—he will collaborate with his father—Weatherhead Professor of Pharmacology John McLachlan, PhD, a national expert in women’s health and estrogen action, and Price Goldsmith Professor of Nutrition Dr. Franck Mauvais Jarvis, a leading researcher on sex differences.
Some Background Science
The Tulane University press release emphasized that it is well accepted in immunology that almost all immune responses are initiated in distinct “immune” organs, called lymphoid tissues. These include the lymph nodes. The lymph nodes behave like immunological train stations where immune cells converge and meet up to respond to various infections or challenges. For example, when a person’s lymph node becomes infected with influenza virus, the immune response starts in nearby lymph nodes, not in the lungs.
The team wanted to discover if immune responses could be induced in non-lymphoid tissues without the help of lymphoid tissues. So, the researchers infected mice with Salmonella bacteria. Helper T cells are some of the most important immune cells in the body. They would be activated in lymph nodes and then accumulate in the liver, a non-lymphoid organ—after exposure to the bacteria. As the helper T cells are activated, a cascade of events unfolds that leads to the most potent and effective immune response possible. It was noted that when they studied the mice that lacked all lymphoid tissues, they made a surprising discovery: only half of the mice exhibited a helper T cell response to the bacterial infection in the liver after infection.
With such a stark difference, the team believed they had inadvertently infected one half of the mice. However, upon a complete examination they found that the only thing that stood out was the biological sex of the mice. Female mice responded well to the infection—e.g. they activated helper T cells that built up in the liver. Could it be that the females have evolved an immune system affording them to react in extra-lymphoid tissues that males do not have?
The Keck Foundation-funded study will support the teams pursuit to delve deeper into these initial findings. They will explore what cells of the adaptive immune system are activated in non-lymphoid tissues in male and female mice when lymphoid tissues are absent. In more detail, they will analyze T cells, B cells which make antibodies, and cytotoxic T cells, which attack and kill viruses and cancers in a multitude of non-lymphoid tissues in response to a variety of changes, including infection and autoimmunity.
W.M. Keck Foundation
They were started in 1954 by the late W.M. Keck, founder of the Superior Oil Company. The foundation’s grant making is focused primarily on pioneering efforts in the areas of medical, science, and engineering research.
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John McLachlan, PhD, a national expert in women’s health and estrogen action
James McLachlan, PhD
Dr. Franck Mauvais Jarvis, Price Goldsmith Professor of Nutrition
Call to Action: If the differences in female and male immune systems catches your attention, we invite you to keep track of this upcoming study.