Low NK activity in large autism subgroup

Low natural killer cell cytotoxic activity in autism: The role of
glutathione, IL-2 and IL-15

Aristo Vojdani, Elizabeth Mumper, Doreen Granpeesheh, Lynne Mielke,
David Traver, Kenneth Bock, Karima Hirani, James Neubrander, Kurt N.
Woeller, Nancy O’Hara, Anju Usman, Cindy Schneider, Frank Hebroni,
Joshua Berookhim and Jaquelyn McCandless.

Journal of Neuroimmunology
Volume 205, Issues 1-2, 15 December 2008, Pages 148-154

Although many articles have reported immune abnormalities in autism,
NK cell activity has only been examined in one study of 31 patients,
of whom 12 were found to have reduced NK activity. The mechanism
behind this low NK cell activity was not explored. For this reason, we
explored the measurement of NK cell activity in 1027 blood samples
from autistic children obtained from ten clinics and compared the
results to 113 healthy controls. This counting of NK cells and the
measurement of their lytic activity enabled us to express the NK cell
activity/100 cells. At the cutoff of 15–50 LU we found that NK cell
activity was low in 41–81% of the patients from the different clinics.
This NK cell activity below 15 LU was found in only 8% of healthy
subjects (p < 0.001). Low NK cell activity in both groups did not
correlate with percentage and absolute number of CD16+/CD56+ cells.
When the NK cytotoxic activity was expressed based on activity/100
CD16+/CD56+ cells, several patients who had displayed NK cell activity
below 15 LU exhibited normal NK cell activity. Overall, after this
correction factor, 45% of the children with autism still exhibited low
NK cell activity, correlating with the intracellular level of
glutathione. Finally, we cultured lymphocytes of patients with low or
high NK cell activity/cell with or without glutathione, IL-2 and
IL-15. The induction of NK cell activity by IL-2, IL-15 and
glutathione was more pronounced in a subgroup with very low NK cell
activity. We conclude that that 45% of a subgroup of children with
autism suffers from low NK cell activity, and that low intracellular
levels of glutathione, IL-2 and IL-15 may be responsible.


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