Lymphocytes, cytokines, inflammation, and immune trafficking.

Studies reported during the past year have added new knowledge to our understanding of cellular abnormalities in systemic lupus erythematosus: 1) Antigen-specific and "pathogenic" T cells display a limited T cell receptor repertoire in lupus. 2) The ratio of interleukin-10 to interferon gamma-secreting cells in the peripheral blood of patients with lupus is increased in patients with active disease. 3) CD3-mediated increases in free intracytoplasmic calcium occur specifically in lupus T cells and lines; this finding provides additional evidence that cell-signaling events are defective in patients with lupus. 4) Aberrant expression of adhesion molecules on the surface membrane of leukocytes and endothelial cells was shown, a finding with important mechanistic and therapeutic implications. 5) Lupus antigen-presenting cells fail to upregulate the expression of B7-1 (CD80) in response to interferon gamma; defective expression of B7-1 is responsible for the decreased response of lupus cells to recall antigens.