Immune Response of a Patient with Deficiency of the Fourth Component of Complement and Systemic Lupus Erythematosus

Abstract

The clinical details of a five-year-old boy with systemic lupus erythematosus and an inherited deficiency of the fourth component of complement (C4) have been reported elsewhere. In this study of his immune responses, immunization with bacteriophage φ X 174 demonstrated diminished antibody formation, abnormal immunologic memory and failure to switch from IgM to IgG during secondary response. We also noted persistent lymphopenia and reductions in peripheral-blood T lymphocytes, lymphocyte responses to mitogens and allogeneic cells and granulocyte chemotaxis. Kinetic studies revealed that delayed activation of the alternative pathway was corrected by purified C4 only if the classical pathway was not blocked.