Abstract
Summary
Fifty-two leukocyte cultures obtained from 28 healthy, normal individuals studied on 35 separate occasions produced a wide range of interferon titers (IF) in response to infection with Newcastle disease virus (NDV) in vitro (< 0.7 to 2654 IU; median 406 IU). This variability could not be correlated with the proportion of mononuclear cells in the culture nor was any correlation noted between the IF titer and simultaneously determined phytohemagglutinin (PHA) blastic transformation. Technical factors could not explain these findings as a similar variability was noted when 10 individuals were studied concurrently. Repeated studies of 2 individuals over 18 months showed marked differences in the IF produced by their leukocytes on these separate occasions. Several subjects were encountered whose leukocytes produced no IF on one occasion, but were responsive to NDV on follow-up study. Spontaneous production of IF by control leukocyte cultures without virus by these individuals, and the group as a whole, was not found. The biological significance of such periods of transient leukocyte hypore-sponsiveness to in vitro virus infection is unknown.
The authors thank Mrs. Alice Cole for her excellent technical assistance in performing these studies.
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