Natural killer response to exogenous interferon in delta hepatitis: boost or depression defined within the first week...

Six patients with hepatitis B surface antigen (HBsAg)-positive chronic active liver disease and superimposed delta virus infection were followed up for changes of natural killer (NK) cell function during a 3-month course with median doses of recombinant leukocyte alpha interferon (rIFN). Careful record of the off-therapy NK function means revealed that 3 subjects were boosted, 2 were depressed, and 1 was unchanged. The NK activity patterns showed that after the start of therapy the maximal shift from the off-therapy mean was concentrated in the first week; then the trend, although confirmed, had a gentler slope on the follow-up. This indicated that the first week reflects the availability of rIFN-sensitive NK cells and characterizes the immunological competence of the patient; whilst later in follow-up, suppressive control mechanisms or loss of receptor affinity tend to blur the response. The serum levels of delta RNA dropped in the NK-boosted patients; persistently negative RNA together with clearance of intrahepatic delta antigen was demonstrated solely in that 1 patient showing 164% NK cell function increment in the first week. This study shows that paradoxical responses to exogenous rIFN are not confined to cancer patients, as indicated so far, but may appear in other subjects as well, and reflect the peculiar response of the individual; whenever an NK-dependent clearance of virus-infected cells is required, recognition of the early pattern of reactivity would be useful.(ABSTRACT TRUNCATED AT 250 WORDS)