To explore the stability of immune reactivity across laboratory
tasks, we correlated enumerative and functional lymphocyte
responses to a speech task and a mental arithmetic task, delivered
on the same occasion of testing in 31 healthy undergraduates.
Both tasks were associated with an increase in peripheral CD8+
and CD56+ cell populations, and a decrease in proliferative
response to phytohemagglutinin (PHA) and ratio of CD4:CD8 cells.
Intertask correlations were significant for the magnitude of
change in proliferative responses at two different concentrations
of PHA, r = 0.76, p < .0001 and r
= 0.46, p < .05, and in numbers of circulating CD56+
cells, r = 0.46, p < .005. Concomitant
heart rate and systolic blood pressure responses also correlated
significantly over the two experimental tasks (heart rate:
r = 0.52 and systolic blood pressure: r =
0.58. ps < .0005). These data provide initial evidence
that interindividual variability of some cellular immune responses
is moderately reproducible across different stimulus conditions,
providing further evidence that it may denote a stable individual
difference.
