Relation between the major histocompatibility (B) locus and autoimmune thyroiditis in obese chickens

Abnormal response to minor histocompatibility antigens in Obese strain chickens

Obese strain chickens, which spontaneously develop autoimmune thyroiditis, were tested for their ability to tolerate skin allografts. Several procedures known to prolong graft survival in normal strains were employed. These included the use of skin matched at the major histocompatibility locus, grafting on the day of hatching, thymectomy, and x-irradiation. A dramatic difference between the Obese and the normal Cornell strain (the strain from which Obese was derived) was detected when both were thymectomized and grafted at hatching. Under these conditions eight of 13 normal but only one of 16 Obese strain birds retained their grafts for 50 days. This suggests the presence of an abnormal thymus or thymus-derived suppressor T cells in Obese strain chickens.

Tumor immunology, autoimmunity and aging

Cell-mediated immune function declines with aging, and may be associated with autoimmunity and malignancy. Humoral immune responses also decline with aging. The chief age-related effect on the immune system is a decrease in T-cell function. The "thymus clock" and immunogenesis are discussed in relation to aging. In animals, attempts at immunologic rejuvenation by cellular or hormonal means have not been successful as the results attained by genetic manipulation.