Distribution and Characterization of Autoantibodies to Interleukin 1α in Normal Human Sera

Antibodies against IL-1α were detected in sera of apparently healthy individuals. The immunoglobulins belonged to the IgG and class, particularly IgG1. IgG2. and IgG4. [125I]rIL-1α bound to Tab fragments of IgG. and IgG immune complexes of molecular weights from 160 to 700 kDa were formed in the sera by [125I]rIL-1α. The occurrence of detectable anti-IL-1α IgG in sera of 32 male and 32 female donors was 25 and 22% respectively. As judged by Scatchard analysis of the binding data, the capacity and avidity of binding were greaser in the male than in the female sera (mean capacity to bind [l25I]rIL-1α 10 [0.7 -27] versus 3.3 [0.5-7.3] ng/ml; and mean Kd:5.5 [5-7] versus 11 [4 16] PM). The antibodies did not cross-bind human recombinant IL-1β, IL-2, 1L-6. or tumour necrosis factor alpha (TNF-α). It is concluded that native IL-1α seems lo trigger production of specific, high-avidity IgG antibodies in a relatively large number of normal individuals. These autoantibodies may regulate immunoinflammatory processes involving IL-1α.