51Cr release microassay for measuring cell-mediated immunity in chickens

Development of optimal conditions for lymphokine production by chicken lymphocytes

Chicken thymus, spleen, and bursa lymphocytes were isolated by different methods and incubated under differing conditions in order to obtain and characterize avian lymphokines. The biological activity of lymphokine-containing cell culture supernatants was measured by their antiviral activity (interferon(IFN)-units) and by their capacity to induce cytostatic effects in bone-marrow-derived macrophages (50% cytostasis-inducing dose, CID). Lymphokine production by thymus lymphocytes required concanavalin A (ConA)-stimulation, while spleen cells, when cultured at high density, released CID and IFN activities into the culture medium even without mitogen-stimulation. By way of comparison, the highest lymphokine content was found in the supernatant of lymphocyte cultures, which were incubated for 72 hours at 41 degrees C after stimulation with an optimal ConA dose. For stimulation of thymus lymphocytes 30 micrograms ConA/ml were found to be optimal, independent of serum content and cell density in the cultures. In contrast, the optimal ConA dose for spleen lymphocytes not only depended on the serum content but also on the cell density in the cultures and varied within a range of 2.5 micrograms and 45 micrograms ConA/ml.

Chronic neurologic disease in Theiler's virus infection of SJL/J mice

This study demonstrates that most SJL/J mice inoculated intracerebrally (IC) with 1000 suckling mouse 50% mean lethal doses of Theiler's encephalomyelitis virus (TMEV) develop flaccid paralysis 10-21 days after infection when there is acute spinal cord gray matter involvement (early disease). Surviving mice later develop a distinctive chronic neurologic disorder which is associated with marked mononuclear cell infiltrates and active demyelination in spinal cord white matter (late disease). Moreover, about one-fourth of infected animals only develop signs of late disease which may begin after an incubation period as long as 2 and a half months. Affected mice are less active, incontinent, and have a waddling, spastic gait. Minimal stimulation induces prolonged extensor spasms of all limbs. These late-developing manifestations of chronic TMEV infection are progressive and clinical remissions have not been observed. The effect of persistent CNS infection on general development was monitored by weekly measurement of body weight; however, the growth of chronically-infected mice was found to parallel that of control animals.