C1 and C4 abnormalities in chronic lymphocytic leukaemia and their significance.

Clinical and laboratory correlations of low C1 and C4 levels previously found to be a characteristic feature of chronic lymphocytic leukaemia (CLL) were analysed. Abnormalities of C4 were restricted to stage 1, 2 and 3 of CLL, whereas in the more advanced disease (stage 4) only low C1 levels were found. It was demonstrated that the observed disorders were associated with an increased susceptibility of the patients for infections and impair the immune complex precipitation inhibiting capacity of the patients' sera as well.