Alloantigen System L Affects the Outcome of Rous Sarcomas1

Abstract

This study was designed to examine the alloantigen system L effects on Rous sarcomas in three B complex genotypes. The parental stock was 50% Modified Wisconsin Line 3 × White Leghorn Line NIU 4 and 50% inbred Line 6.15-5. Pedigree matings of two B2B5 L1L2 sires to five B2B5 L1L2 dams per sire produced experimental chicks segregating for B and L genotypes. Chicks were inoculated with 20 pock-forming units (pfu) of Rous sarcoma virus (RSV) at 6 weeks of age. Tumors were scored six times over 10 weeks postinoculation after which the tumor scores were used to assign a tumor profile index (TPI) to each chicken. Tumor growth over time and TPl were evaluated by repeated-measures analysis of variance and analysis of variance, respectively. Six trials were conducted with a total of 151 chickens. The major histocompatibility (B) complex affected the responses as the B2B2 and B2B5 genotypes had significantly lower tumor growth over time and TPl than the B5B5 genotype. Separate analyses revealed no significant L system effect in B2B2 or B2B5 backgrounds. However, L genotype significantly affected (P < 0.05) both tumor growth over time and TPl in B5B5 chickens. B5B5 L1L2 birds had TPl significantly lower than B5B5 L1L1 chickens but not B5B5 L2L2. Mortality was lower in the B5B5 L1L2 birds than in B5B5 L2L2 chickens. The L system, or one closely linked, affects the growth and ultimate outcome of Rous sarcomas. The response may depend upon the genetic background as well as MHC type.