Transport of Neutral and Dibasic Amino Acids by Human Leukocytes: Absence of Defect in Cystinuria*

Transport and Intracellular Fate of Cysteine-35S in Leukocytes from Normal Subjects and Patients with Cystinosis

“…Inulin-carboxyl-14 C (S.A. 3 mC/g with an average molecular weight of 5000-5500) [39] was used for determing extracellular volume as described by ROSEN-BERG [22]. Arginine-»C (U.L., S.A. 220 mC/mmole) was also obtained commercially [39], as was glucose-1-"C (S.A. 1.72 mC/mmole) [40].…”

“…The suspensions were immediately centrifuged at 120 Xg for 10 minutes at 4°. Virtually no transport of amino acids occurs at this temperature [22]. The supernatant was saved and the leukocytes and thiolated sephadex suspended in 2 ml of normal saline (4°) and then immediately centrifuged in precooled Bauer-Schenck tubes [32] at 2200Xg for 10 minutes at 4°.…”

“…The distribution ratio was calculated as described by ROSENBERG [22] and represents the ratio of the concentrations of intracellular to extracellular radioactivity. A correction was required, however, for the small amount of cysteine- 35 S which remained attached to the thiolated sephadex.…”

“…The lack of studies of postmortem tissue from these patients have suitable tissue from infants and small children with revealed normal activity of all enzymes tested, which this disease has been a major obstacle to definitive included most of those known to be necessary for cys-studies of transport. Leukocytes provide a readily available tissue for study, although ROSENBERG [22] found poor uptake of cystine by normal leukocytes. We have confirmed this observation in both normal and cystinotic leukocytes; however, both types of leukocytes showed a substantial uptake of the reduced form, cysteine.…”

Prolinuria: Transport of Proline by Leukocytes

“…The distribution ratio,3 defined as the ratio of counts per milliliter intracellular fluid to the counts per milliliter medium was calculated as a measure of intracellular amino acid accumulation, according to Rosenberg and Downing's formula. 3 The packed cell volume was calculated from the correlation curve, prepared previously, between the volume and number of leukocytes which was found to be almost linear. A part of the skin tissue biopsied was also subjected to histological examinations.…”