Decreased C'-1q protein concentration and agglutinating activity in agammaglobulinaemia syndromes: an inborn error reflected in the complement system

Abstract

In both C'_1q protein and agglutination assays, markedly reduced mean titres (27 and <10% normal, respectively) were observed in Swiss type lymphopenic agammaglobulinaemia. Mean C'_1q titres were somewhat decreased in other forms of agammaglobulinaemia, but not to the same degree (78 and 46% normal, respectively). C'_1q titres were normal or elevated in other diseases associated with repeated infections and malignancy.

We conclude that the C'_1q globulins, like the immunoglobulins, characteristically are deficient in agammaglobulinaemia syndromes. Since the greatest C'_1q deficiencies were seen in lymphopenic agammaglobulinaemia of the Swiss type, titration of C'_1q seems to be a convenient aid in diagnosing this disease early in life.

Thus, the inborn error of agammaglobulinaemia seems to be reflected in the complement system.