The immune status of 29 members of the Australian National Antarctic R
esearch Expeditions (ANARE) was investigated before, during, and after
a 56 day summer voyage to Antarctica and correlated with psychologica
l and physiological parameters. All subjects were healthy. Expedition
personnel demonstrated decreased cell mediated immune responses (CMI)
assessed by the CMI Multi-test; 21% were hypoergic. The major associat
ed observation was a significant negative correlation with anxiety in
Antarctica. However, perceived anxiety was greater before and after th
e voyage. No significant changes were found in T and B lymphocyte subs
ets, immunoglobulin and complement components and cutaneous blood flow
, nor was there any clinical evidence of illness. Of the hormones exam
ined only cortisol was low predeparture which may reflect increased pe
rceived anxiety at that time. Changes in immune control mechanism were
apparent as shown by reduced CMI responses and lowered tetanus antibo
dy levels. Stress factors are postulated to induce depression of the i
mmune response in Antarctica. The association with anxiety suggests th
at brain peptides or associated cytokines may have a role in mediating
these immune events. Such alterations in immune status have implicati
ons for health management in isolated and extreme conditions.