B and T cell immunity in patients with lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is characterized by defective cellular transport of the dibasic amino acids, secondary dysfunction of the urea cyc le, aversion to dietary protein, failure to thrive, hepatosplenomegaly and osteoporosis. Because several patients have suffered from recurrent respira tory infections and/or severe generalized varicella, and a few have develop ed systemic lupus, vasculitis or other autoimmune diseases, we have now eva luated the function of patients' immune systems. Serum concentrations of on e to three IgG subclasses were decreased in 10 of the 12 patients studied. Antibody titres against diphtheria, tetanus and Haemophilus influenzae (Hib ) were below the detection limit of the assay in four, three and eight of t he 11 patients examined, respectively. (Re) vaccination of these 11 patient s led to satisfactory responses against tetanus, but two patients still fai led to develop measurable antibodies against diphtheria, two against Hib an d six against one or more of the three serotypes of 23-valent pneumococcus vaccine. The proportions of T cells of all lymphocytes and the proliferativ e responses of the peripheral blood mononuclear cells were normal. In concl usion, humoral immune responses in some patients with LPI are defective and these patients may benefit from intravenous immunoglobulin therapy.