Natural killer (NK) cell activity was measured blindly in
vitro with blood specimens from 50 healthy individuals and 20
patients with clinically defined chronic fatigue immune
dysfunction syndrome (CFIDS) who met the criteria established
by the Centers for Disease Control and Prevention (Atlanta).
In accordance with a group scoring system of 1-10 points, with
10 being the most severe clinical status, the patient
population was stratified into three clinical groups: A (> 7
points), B (5-7 points), and C (< 5 points). NK cell activity
was assessed by the number of lytic units (LU), which for the
50 healthy controls varied between 20 and 250 (50%, 20-50 LU;
32%, 51-100 LU; 6%, 101-130 LU; and 12%, > 150 LU). In none of
the 20 patients with CFIDS was the NK cell activity > 100 LU.
For group C, the 10 patients stratified as having the least
severe clinical condition, the measure was 61.0 +/- 21.7 LU;
for group B (more severe, n = 7), it was 18.3 +/- 7.3 LU; and
for group A (most severe, n = 3), it was 8.0 +/- 5.3 LU. These
data suggest a correlation between low levels of NK cell
activity and severity of CFIDS, which, if it is confirmed by
additional studies of larger groups, might be useful for
subgrouping patients and monitoring therapy and/or the
progression of CFIDS.
Ojo-Amaize EA, Conley EJ, Peter JB