Familial studies on the occurrence of natural autoantibodies.

Natural autoantibodies are often incidentally found in healthy individuals who are not first-degree relatives of known patients with autoimmune diseases. In an attempt to examine whether there exists a familial tendency in the production of such natural autoantibodies, 134 healthy members of 32 families were examined for antibodies against ss-DNA, ds-DNA, poly (I), poly (G), cardiolipin, histones, Sm, RNP, SS-A (Ro) and SS-B (La), using an enzyme-linked immunosorbent assay. Only 16 of the 134 subjects (11.9%) were found to possess autoantibodies in their sera in a titer exceeding the mean by 3 SD, and none of the 'positive' subjects were related. We conclude that in contrast to the familial occurrence of the autoantibodies of first-degree relatives of patients with autoimmune disease, there is no familial tendency in the occurrence of natural autoantibodies.