% Decrease in NKCC in CFS vs. Controls CFS Case Definition Number of Patients and Controls Studied Comments Reference
↓ 64% - (median) p<0.001 1988 CDC CFS: 30
Healthy: 73
E:T ratio 1:1, K562=target [7]
↓ NKCC (no values provided)
p<0.03
1988 CDC CFS: 5
NC:4
Age/sex matched, published as a letter,6 E:T ratios from 100:1 to 3:1, K562=target [25]
↓ 72%-75% (mean) p<0.01 1988 CDC CFS: 10
Fatigue non-CFS: 24
Healthy Non-fatigued controls: 21
2 E:T ratios, 10:1 and 20:1, K562=target [26]
↓ NKCC (no values provided) p<0.05 1988 CDC CFS: 20
Healthy: 50
4  E:T ratios 50:1 to 6.25:1, K562=target [27]
↓68% (LU) 1988 CDC CFS: 16
Healthy: 12
E:T ratios from 50:1 to 6.25:1, K562=target [28]
No↓ seen (no values provided) 1988 CDC CFS: 21
NC: 21
Age/sex matched, E:T ratios not provided, K562=target [29]
No↓ seen at each of 5 E:T ratios 1988 CDC CFS: 16
Healthy: 50
5  E:T ratios from 50:1 to 3:1, K562=target [30]
↓63% (mean LU) 1988 CDC CFS: 20
NC: 20
4 E:T ratios from 40:1 to 5:1, K562=target [31]
↓63% (mean LU) p<0.05 1988 CDC CFS: 91a
NC: 30
Target cell = (HHV-6)- infected H9 cells, 4 E:T ratios 40:1 to 5:1 [24]
↓62% (median LU) p<0.006 1988 and 1994 CDC CFS: 8
UFM: 12
NC: 8
Family members with CFS and unaffected family members (UFM), 4 E:T ratios 50:1 to 6:1, K562=target [32]
↓42% (mean) p<0.003 1994 CDC CFS: 29
Healthy: 29
Series of 29 consecutive CFS patients; E:T ratio 1:1, K562=target [9]
↓46% p<0.001 1994 CDC CFS: 30
Healthy sedentary controls: 19
E:T ratio 1:1, K562=target [34]
↓57% (median) p<0.001 1994 CDC CFS: 176
Healthy: 230
E:T ratio 1:1, K562=target [12]
NC: Normal Controls; LU: Lytic Units
aSubset of CFS patients meeting the CDC 1988 CD, but with lower levels of CD5, CD8, and CD11a mononuclear cell membrane receptors.
Table 1: Studies investigating NK cell cytotoxicity in CFS using 51Cr release assays.