Enhancement of human natural cell-mediated cytotoxicity by interferon

The effect of exogenous Namalva interferon (IF) on the natural killer (NK) cell activity of human blood lymphocytes was examined against 5 target cell lines (K562, CCRF/CEM, Molt 4, Raji and Bri8) using the 51Cr-release assay. Addition of IF to the test significantly increased the cytotoxicity, though not as much as when effector cells were treated with IF before the test. Augmentation of cytotoxicity was evident after only 1 h pretreatment and was maximal by 6 h. The rate of lysis of susceptible targets by IF-treated effectors markedly exceeded that by their untreated counterparts. Separation of lymphocyte subpopulations (by SRBC-rosette sedimentation and nylon-fibre column filtration) demonstrated that the activities of IF-stimulated and unstimulated cells were similarly distributed, suggesting that the major effect of IF is enhancement of the activity of pre-existing NK cells rather than generation of new populations of effectors. Target cell lines with high and low susceptibility to NK cells showed increased cytotoxicity by IF-treated effector cells. These findings may be relevant to the current discussion of the role of NK cells in immunosurveillance against neoplasia.     

The effect of an intravenous infusion of hypertonic saline on renal mechanisms and on electrolyte changes in sheep

1. The ability of the sheep to tolerate excess sodium chloride has been investigated by subjecting sheep to an intravenous infusion of a 10% solution of sodium chloride.2. Inulin and diodrast clearances failed to show any consistent changes in glomerular filtration rate but the effective renal plasma flow was slightly more. Plasma levels of sodium and chloride increased by 20-25% and potassium decreased by 30%. Urinary levels for sodium and chloride showed a corresponding increase and potassium excretion was reduced.3. The rates of re-absorption of sodium and chloride from the renal tubules were found to be proportional to their rates of filtration at the glomerulus, but this ratio was reduced after the hypertonic saline infusion. No such correlation could be established for potassium.4. Osmolar clearances indicated that continued re-absorption of osmotically free water from the kidney tubular fluid occurred during and after the hypertonic saline. Excretion of urine, hyperosmotic to plasma, was thus maintained and water conservation supported.5. Possible renal mechanisms associated with these effects are discussed.     

INCREASED FIXATION OF SULFUR35 BY CARTILAGE IN VITRO FOLLOWING DEPLETION OF THE MATRIX BY INTRAVENOUS PAPAIN

The uptake in vitro of sulfur-35 by costal cartilage obtained from nine rabbits 11 days after an intravenous injection of crude papain solution was compared with that in costal cartilage from eight normal untreated rabbits. An increased fixation of the isotope was found in treated animals compared with controls. The depletion of cartilage matrix by papain provided an experimental situation to test the hypothesis that the depletion of matrix which occurs in osteoarthritic cartilage can stimulate increased synthesis of chondroitin sulfate. The results give further support to the view that the primary lesion in osteoarthritis occurs in the matrix rather than in the chondrocyte of articular cartilage.