Heteroagglutinins and spontaneous rosette-forming cells in obese strain (OS) chickens.

Sera of OS chickens with spontaneous autoimmune thyroiditis (SAT) and of normal white Leghorn (NWL) controls, aged 4-20 weeks, were studied for the presence of heteroagglutinins to sheep (SRBC) and rabbit red blood cells (RRBC). Significantly higher frequency and titers of SRBC- and RRBC-agglutinins were found in OS as compared to NWL birds, the difference being more accentuated with RRBC. The number of spontaneously rosette-forming peripheral blood lymphocytes (RFC) with SRBC and RRBC was determined in 20-week-old OS and NWL chickens. The number of RRBC-RFC was found to be significantly elevated in the OS. The value of RFC did not correlate with the individual heteroagglutinin titers. RFC and heteroagglutinin secreting cells are considered to be nonidentical. These results are discussed in the light of the previously established hyperreactivity of the B-dependent portion of the immune system in OS chickens.