Transcobalamin II, a serum protein reflecting autoimmune disease activity, its plasma dynamics, and the relationship to established serum parameters in systemic lupus erythematosus

Earlier investigations have shown that the activity of autoimmune diseases appears to correlate with increased levels of the vitamin B12 (cobalamin)-binding serum protein, transcobalamin II (M. Fráter-Schröder et al., Schweìz. Med. Wochensch 110, 1441, 1980; M. Fráter-Schröde et al., Lancet 2, 238, 1978). These preliminary findings were confirmed and extended with regard to SLE in the present prospective study. The correlation of serum levels with the degree of disease activity (determined by clinical scoring of 44 patients with systemic lupus erythematosus (SLE), fulfilling four or more of the American Rheumatoid Association criteria) was shown to be most reliable for transcobalamin II (P less than 0.001), when compared to other serological parameters. An answer to the question "what induces increased levels of transcobalamin II in active SLE?" was sought by injecting 15 SLE patients with cyanocobalamin which influences plasma dynamics of transcobalamin II. Results indicate that transcobalamin II-cobalamin "clearance" is probably unchanged in SLE, and that increased production or stimulation of transcobalamin II secretion may be the cause of elevated plasma levels in active SLE.