The battle of the sexes probably began when first two
gender-specific creatures crawled out of the primordial
sludge. Biologically, women have proven to outperform
men in at least one aspect — they're immune systems
are stronger. This difference has baffled scientists for
some time but we're getting closer to uncovering the secret.
In fact, testosterone — that distinctly manly hormone
— may be the culprit holding back the male immune
system, according to research published in the November
15 issue of the Journal of Immunology.
"What we are showing is that testosterone
seems to impede immunity," said Dr Eugene Kwon, a urologist
and immunology researcher at the Mayo Clinic in Rochester,
MN. "When testosterone is withdrawn, you get an increased
host immune response indicated by the rising numbers
of immune cells that are available to participate."
AXE
ANDROGEN
Research has already noted that the immune system's
B-cells multiply and lymph nodes swell upon androgen
deprivation or upon removal of testosterone from the
body. The researchers were also hoping to find the mechanism
through which androgens like testosterone interact with
the immune system. This study examined the effect of
androgen deprivation on T-cell counts and efficacy.
Male mice were either surgically
castrated or sham-castrated, where pericordal fat was
removed instead of the testicles. T-cell expression
was measured under several conditions including antigen
stimulation, chemotherapy, thymus glands removal and
in cell culture.
Androgen deprivation caused the
T-cells to multiply and become more reactive to antigenic
stimulation, confirming that testosterone affects T-cell
numbers and function. However, adding testosterone back
into androgen deprived T-cell cultures didn't decrease
the number of T-cells or change the cells' characteristics.
This means that testosterone isn't directly interacting
with the immune cells to hinder their growth.
THE
USUAL SUSPECTS
But when testosterone is away, other hormones may play.
Since testosterone suppresses the production of prolactin,
luteinizing hormone, estradiol and other hormones, an
increase in one of these could be causing the enhanced
immune response. More research is needed to establish
a cause-and-effect relationship between the presence
of various sex hormones and the potency of the immune
response.
Once that relationship is found
it could lead to a new way for doctors to hasten the
recovery of the immune system after immunosuppression
resulting from chemotherapy, burn injuries and blood
loss. As the authors wrote, "These studies may have
implications for enhancing immune responses to immunotherapy,
for improving immune system recovery following chemotherapy,
and for establishing a mechanistic basis whereby gonadal
steroid hormones modulate autoimmunity."
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