The role of the kidney in the catabolism of Bence Jones proteins, intact IgG molecules, and isolated L chains, Fab and Fc fragments of IgG, was studied. The proteins were purified, radioiodinated, and their survival times measured in nephrectomized, ureter-severed, and control mice. Active endogenous catabolism was the major factor in overall Bence Jones metabolism since excretion as proteinuria accounted for less than 25% of the total metabolism. The survival times of λ- and κ-type human Bence Jones proteins and the Bence Jones protein produced by mice with MPC-2 plasma cell tumor were exceedingly short in both unoperated and ureter-severed mice, with 50% of the injected protein catabolized in from 0.8–1.6 hr. In contrast, the survival of Bence Jones protein was markedly prolonged in nephrectomized animals, with 50% of the injected dose catabolized in from 9 to 17 hr. This ten-fold decrease in catabolic rate indicates that the kidneys are the major site of breakdown of Bence Jones proteins. Similar studies with other proteins indicated that the kidneys are also the major site for catabolism of isolated L chains but not of intact IgG molecules. The Fc immunoglobulin fragment was not catabolized and the Fab fragment only partially catabolized by the kidney. When ureter-severed animals were allowed to develop advanced uremia before being studied, the survival of Bence Jones protein was greatly prolonged, indicating that the catabolic process is impaired in the presence of uremia. The nature of this renal catabolism remains unknown. These observations suggest that the Bence Jones proteins and L chains observed in the urine of patients may reflect only a small fraction of such molecules synthesized by these patients. Furthermore, they provide an explanation for the prolongation of Bence Jones protein survival and the development of Bence Jones proteinemia observed in subjects with multiple myeloma and impaired renal function.

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Abstract. Intestinal lymphangiectasia is a disease characterized by dilated intestinal lymphatics, protein-losing enteropathy, hypoalbuminemia, and edema. The immunologic status of 18 patients with intestinal lymphangiectasia was studied. Concentrations of IgG, IgA, and IgM were measured by immune precipitation and metabolism of these three immunoglobulins was studied using purified radioiodinated proteins. The serum concentration and total body pool of each immunoglobin were greatly reduced. The fraction of the intravascular protein pool catabolized per day was increased to 34% for IgG, 59% for IgA, and 66% for IgM; these are in contrast with control values of 7%, 28%, and 17%, respectively. Synthetic rates of the immunoglobulins were normal or slightly increased.Primary circulating antibody response was tested in five patients with Vi and tularemia antigens. Titers elicited in patients with the Vi antigen were significantly lower than those seen in a control group, whereas no difference was seen between patient and control responses to the tularemia antigen.Lymphocytopenia was noted in patients with intestinal lymphangiectasia. The mean circulating lymphocyte count was 710 + 340/mm8 in contrast to 2500 + 600/ mm3 in controls. Cellular hypersensitivity was studied with skin tests and skin grafts. 91% of normal individuals reacted to at least one of the four skin test antigens: purified protein derivative, mumps, Trichophyton, and Candida albicans; in contrast, only 17% of patients with intestinal lymphangiectasia had a positive reaction. Each of three patients tested with dinitrochlorobenzene had a negative reaction. Finally, all four patients who received skin homografts have retained these grafts for at least 12 months. The immunological disorders in patients with intestinal lymphangiectasia appear to result from loss of immunoglobulins and lymphocytes into the gastrointestinal tract secondary to disorders of lymphatic channels. Lymphocyte depletion then leads to skin anergy and impaired homograft rejection.

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