Effects of chicken anemia agent on lymphokine production and lymphocyte transformation in experimentally infected chickens.

One-day-old chicks with no maternal antibodies to chicken anemia agent (CAA) were inoculated intramuscularly with CAA grown in MDCC-MSB1 cells. A control group of birds from the same source was inoculated intramuscularly with a lysate from uninfected MSB1 cells. Birds were killed at 8, 15, 22, 29, and 43 days postinoculation (PI), and the spleens were removed. Spleen cells were dispersed and stimulated with various concentrations of Concanavalin A (Con A), and lymphocyte transformation responses were determined. Supernatants from Con A-stimulated cultures were assayed for T-cell growth factor (TCGF) and interferon. Decreased lymphocyte transformation and TCGF production were demonstrated at 8 and 15 days PI. This was followed by a stimulation in activities before a return to control levels at 43 days PI. Interferon levels were elevated 8 days after infection. This was followed by a significant decrease in activity compared with controls at 15, 22, and 29 days PI, and a return to control levels by 43 days PI. The results suggest that CAA infection in young chickens can produce a dramatic decrease in immune competence, which, although transitory, is likely to seriously compromise the ability of birds to mount a successful immune response to invading pathogens.