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Young adults with juvenile arthritis in remission attain normal peak bone mass at the lumbar spine and forearm

OBJECTIVE To assess the impact of disease activity on acquired peak bone mass and bone turnover in young adult patients with either persistent juvenile arthritis (JA) or a history of JA (JA in remission). METHODS Two hundred twenty-nine patients with JA were studied after a mean +/- SD of 15.6 +/- 2.4 years in women and 14.9 +/- 2.1 years in men since disease onset. One hundred forty-five women and 84 men were over the age of 20 at the time of examination (mean +/- SD age 24.9 +/- 2.9 years for women and 25.2 +/- 3.1 years for men). Forty-one healthy women (mean +/- SD age 27.4 +/- 3.1 years) and 55 healthy men (mean +/- SD age 25.7 +/- 3.1 years) served as a reference group. Bone mineral density (BMD) was analyzed by dual x-ray absorptiometry. Serum osteocalcin concentrations and urinary concentrations of deoxypyridium (D-Pyd) were measured. Linear regression analyses were performed to evaluate the impact of disease on BMD. RESULTS Patients with persistent disease had significantly lower BMD compared with healthy subjects (P < 0.001 for women at all measured sites and for men at the femoral neck and total body; P < 0.05 for men at the radius and lumbar spine). Of the patients with a history of JA, only women had significantly lower BMD at the femoral neck and total body (P < 0.05). Patients with persistent JA had significantly more osteopenia and osteoporosis than healthy subjects, while patients with a history of JA had more frequent osteopenia only in the total body. Weight, urinary concentration of D-Pyd, and belonging to the patient group significantly affected BMD at all measured sites in the entire study population, while analysis of all patients found that only the number of months taking corticosteroids significantly affected BMD at all measured sites. However, the impact of the variables differed from site to site. CONCLUSION Our findings imply that most young adults with JA attain the same BMD as healthy subjects if the disease goes into remission, while young adults with active disease have increased risk for osteopenia and osteoporosis.

Natural Killer Cells in Autoimmune Diseases

Natural killer cell activity was first recognized around 1970 (McCoy et al., 1973; Takasugi et al., 1973). This activity can be demonstrated without the apparent previous sensitization of the effector cells. It has therefore been termed either spontaneous or natural cell-mediated cytotoxicity (Takasugi et al., 1977), spontaneous lymphocyte-mediated or mononuclear cell cytotoxicity (Pross and Baines, 1977), and now usually natural killer (NK) cell activity. The effector cells responsible for this activity are called natural killer cells (NK cells). They are considered to be distinct from other cells capable of mediating spontaneous cytotoxicity such as cytotoxic T lymphocytes and monocytes (Ritz et al., 1988). In vitro lymphokine-activated killer (LAK) cells are interleukin-2 (IL-2)-stimulated lymphocytes with the ability to lyse NK resistant target cells in vivo (Grimm et al., 1982). However, LAK cells have so far not been shown to represent a distinct effector cell population. They mostly appear to represent IL-2-stimulated NK cells with enhanced cytolytic activity (Ritz et al., 1988; Lotzova and Ades, 1989).