Absence of protection against challenge with Aspergillus fumigatus by adoptive transfer of splenocytes from convalescent turkeys

Only limited protective immunity against aspergillosis after experimental i mmunization of turkeys has been previously demonstrated. No studies evaluat ing the efficacy of transfer of immunity in preventing aspergillosis in bir ds have been reported. This study consisted of two trials assessing the lev el of protection against Aspergillus fumigatus challenge afforded by transf er of splenocytes from convalescent turkeys. Three treatment groups of 12-t o-14-wk-old Beltsville small white (BSW) turkeys comprising the splenocyte donors were prepared by one of the following: 1) intra-air sac (IA) challen ge with A. fumigatus conidia 5 wk prior to transfer; 2) IA challenge and th en intravenous (IV) injection of killed conidia 1 wk prior to transfer; or 3) sham inoculations. Splenocytes from each group were pooled, enriched for mononuclear leukocytes by density gradient centrifugation, and diluted in cell culture medium (CM). Cell viability was assessed by dye exclusion. Eac h splenocyte preparation was administered intravenously to one of three rec ipient groups consisting of 10 BSW turkeys each. A control group (n = 10) w as given cell-free CM. Recipients were challenged with viable A. fumigatus conidia 16 hr after splenocyte transfer by unilateral IA (trial I) or IV (t rial 2) inoculation. Lesion scores postchallenge revealed no differences be tween turkeys given splenocytes from convalescent ys. naive (control) turke ys. IA exposure produced ipsilateral lesions in air sacs and lung, whereas TV exposure produced severe miliary hepatitis. Donor cell function was conf irmed by mitogen blastogenesis; however, cells were nonresponsive to A fumi gatus antigens, regardless of previous exposure status.