A family study of leprosy: subcutaneous amyloid deposits and humoral immune responses.

One group of 11 aboriginal families, consisting of 27 persons with leprosy and 43 unaffected family members, and a second group of 26 patients with leprosy were studied in the Northern Territory of Australia. Amyloid deposits were sought in fine needle aspirates of subcutaneous fat and serological investigations relevant to amyloidosis and to the humoral immune response were done. The study showed unexpectedly high frequencies of amyloid deposits, evidence of persisting hepatitis B virus (HBV) infection, and antibodies to smooth muscle, to skin basement membrane, and to extractable nuclear antigens (ENA). Compared with unaffected family members, patients with leprosy had increased serum alpha-lipoprotein (alpha-LP) and were more often hepatitis B surface antigen (HBsAg) carriers but, contrary to expectations, the presence of amyloid, the alpha-LP level, serum amyloid associated (SAA) protein, and the HBsAg carrier state all appeared unrelated to the type of leprosy.