According to the researchers, the findings could have profound implications for human health.
Researchers have long remained puzzled by the question why immune activity is variable in many wild animals.
Referring to previous work on Peromyscus and other small mammals and birds, Martin said: "Animals live different lifestyles, so they may use different types of defenses against infection depending on the situation.
"Perhaps this is why immune defenses vary seasonally in most species; some may be too expensive to use all the time," Martin added.
It is already known that the immune system expends energy when it gears up to fight a virus or an infection.
In the study, the researchers found that restricting their subjects' diet by 30 percent significantly decreased the amount of available B cells, which produce antibodies and maintain immune memory.
Without B cells, the immune system must relearn how to fight a threat if it reappears.
Martin and colleagues cite previous studies that have found that infections are 'more frequent and tend to be chronic in malnourished children.'
Vaccines, in order to work effectively, must provoke B cells to produce sufficient antibodies for immune memory.
Earlier studies have found that vaccines such as those for measles have a significantly lower rate of efficacy among the malnourished.
"A 30 percent restriction in food intake doesn't affect body mass and only minimally reduces activity in deer mice, but it eliminates the long-term immune protection provided by antibodies. Martin said.
"One wonders whether similar moderate food restriction has comparable immune effects in humans," Martin asked.
Although other variables may be at work, the authors propose that for both wild animals and humans, food availability impinges on immunity and future research should determine what specific components of a diet are responsible.
The study will be published in May/June 2008 issue of Physiological and Biochemical Zoology.