Hypocomplementemia in Multiple Myeloma

We report the results of a prospective study of the complement system in a cohort of 22 multiple myeloma patients: 11 women and 11 men, median age 66 years. There were 10 IgG, 8 IgA, 2 IgM and 2 light chain myeloma patients. Seven were in stage 1, 3 in stage 2 and 12 in stage 3. The serum complement component levels of the three pathways were measured in all patients and compared to normal values of 29 healthy controls. We found a depleted common pathway in 21 patients, and deficient alternative and terminal pathways in 6 patients. There was no difference in the complement profile of myeloma patients in the advanced or early stages of the disease. IgG and IgA myeloma patients had a similar complement profile. Nine patients, 7 with advanced disease, developed 17 infectious episodes. Most of these patients had a deficient classical pathway, but normal alternative and terminal pathways. This profile was not different from the complement system observed in patients without infectious complications.Activation ...