PubMed Health⌕ Search

Biomedical subjects

D M Kenney

Publications and source records attributed to D M Kenney.

6 recordsLinked to original sources
PubMed1992

T cell lines characterize events in the pathogenesis of the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is a severe immunodeficiency and platelet deficiency disease arising from an X-linked defect. The disease is correctable by transplantation of hematopoietic stem cells, but the product of the defective gene is unidentified and the number of defects in patient blood cells is large. The current hurdle is the need to identify the early pathogenic event(s) that are the cause of other defects. As a step toward this goal, we have generated and examined a panel of interleukin 2-dependent allospecific T cell lines from peripheral lymphocytes of seven WAS patients and five normal individuals. WAS cell lines, like normal lines, undergo vigorous proliferation when challenged with specific allostimulant or with phorbol myristate acetate and ionomycin. Both normal and WAS T cell lines express cell surface molecules CD2, CD3, T cell receptor-alpha/beta, human histocompatibility leukocyte antigen class I, CD45 and CD11a, and varying ratios of CD4 and CD8, and are negative for natural killer cell and monocyte surface molecules. WAS T cell lines express CD43 (sialophorin/leukosialin) with molecular weight and in an amount comparable with normal T cell lines. WAS T cell lines thus do not express defects in CD43 (decreased amount, abnormal molecular weight), previously documented in WAS circulating lymphocytes. On the other hand, as detected by scanning electron microscopy, WAS cell lines exhibit severe morphological abnormalities, including decreased size and density of the microvillus surface projections. The morphological abnormalities of WAS T cell lines are similar to, or more extensive than, those previously reported for WAS peripheral lymphocytes, indicating that the generation of morphological (cytoarchitectural) defects is an early pathogenic event in this disease. The findings suggest that the gene that is defective in the WAS encodes a protein that normally functions to maintain or regulate the cytoskeletal structure of blood cells.

Adolescent↗
PubMed1992

Effect of platelet calpain on normal T-lymphocyte CD43: hypothesis of events in the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is an inherited disease involving defects of platelets (small size, severe thrombocytopenia due to accelerated destruction) and T lymphocytes (progressive immunodeficiency, lymphopenia). The best-characterized molecular defect is the deficiency and, in some cases, abnormal forms of the T-lymphocyte surface mucin molecule CD43; deficiency of the platelet surface mucin GPIb was observed previously in two of four patients. Neither of these defects is primary, since CD43 and GPIb are encoded by autosomal genes and the disease is X-linked. This study uses cellular biological approaches to explore the possibility that destruction of structurally defective WAS platelets, mimicked experimentally by sonication of normal platelets, plays a role by releasing protease and generating other cellular defects. We show that a protease of normal platelets, identified as Ca(2+)-dependent neutral protease (calpain), which is known to cleave platelet GPIb, also specifically cleaves CD43 on the surface of neighboring desialylated T lymphocytes. The identification of the CD43 cleaving protease was based on its requirement for Ca2+ and inhibition by leupeptin, but not by diisopropylfluorophosphate (DFP). The approximate site of CD43 cleavage was identified by the use of a rabbit antibody. Sensitivity of GPIb to calpain is shown to be sialylation-independent and that of CD43 to be sialylation-dependent, and these findings are explained in terms of molecular structures. These and previous findings are incorporated into a putative mechanism, which explains most of the defects in the WAS. The mechanism suggests that the primary defective molecule in the WAS is unlikely to be a surface glycoprotein, but rather a cytoplasmic molecule with a function in cytoskeletal interactions and/or calcium ion regulation and calpain activation.

Antigens, CD↗
PubMed1979

Effect of sodium chloride on limulus amebocyte lysate. Inhibition of endotoxin activation of procoagulase.

Concentrations of sodium chloride up to 3 M increase the time necessary for the clot formation from Limulus amebocyte lysate (LAL) induced with endotoxin. Sodium chloride at a concentration of 4 M prevents clot formation by either precipitation or denaturation of procoagulase. The time necessary for the activation of procoagulase by endotoxin is increased by a change in the sodium chloride concentration from 0.15 M to 0.588 M. No effect on the proteolytic phase or the polymerization phase of the clotting reaction is detected by the increase in sodium chloride concentration from 0.15 M to 0.588 M. The authors conclude that increased sodium chloride concentrations may aid the isolation of procoagulase.

Animals↗
PubMed1979

Properdin factor D: effects on thrombin-induced platelet aggregation.

Factor D, when preincubated with platelet suspensions, at concentrations as low as 1.2 micrograms/ml, inhibited thrombin-induced platelet aggregation. No inhibition of collagen or arachidonic acid-induced platelet aggregation was found. Inhibition occurred, but to a lesser extent, when thrombin and factor D were added to platelets at the same time. No inhibition occurred when factor D was added after thrombin. Thrombin was able to overcome inhibition by factor D by increasing its concentration. Diisopropyl-phosphorofluoridate-inactivated factor D also inhibited thrombin-induced platelet aggregation so that enzymatic activity of factor D was not required for inhibition. Factor D absorbed with hirudin coupled to Sepharose 6B showed no decrease in inhibitory capacity. 125I-Factor D bound to platelets in a manner suggesting an equilibrium reaction similar to thrombin. At low factor D input, binding was linear, whereas at higher input, binding began to approach saturation. Binding of 125I-labeled thrombin to platelets was inhibited by factor D. Analysis of these data show that factor D does not alter the total number of thrombin molecules which bind to the platelet surface at saturation. However, the dissociation constant for thrombin is altered from 2.78 to 6.90 nM in the presence of factor D (20 micrograms/ml). Factor D is thus a competitive inhibitor of thrombin binding, although the affinity of factor D for the platelet thrombin receptor is much less than that of thrombin. These phenomena occur at physiologic concentrations of factor D. Therefore, factor D may function in vivo as an inhibitor of platelet aggregation.

Binding, Competitive↗
PubMed1975

Colchicine uptake and binding by human platelets.

The uptake and binding of antimitotic alkaloid colchicine has been demonstrated in washed preparations of human pletelets. A silicone oil technique was adapted so that both uptake and binding of 14C-colchicine were examined in the same platelet preparations. The time dependence and amount of colchicine taken up and bound by different pletelet preparations during a 90 to 120 min incubation period were highly reproducible. Both colchicine uptake and binding by intact platelets, and colchicine binding by preparations of lysed platelets were specific and temperature dependent. Colchicine uptake was slowly reversible. Magnesium and GTP enhanced colchicine binding by lysed platelet preparations but calcium decreased binding. exposure of platelets to either cold (4 degrees C) or to thrombin, which disrupt platelet microtubules, produced significant increases in colchicine uptake and binding. The thrombin effect was maximal at 37 degrees C and resulted in a greater increase in uptake and binding than that produced by either cold treatment alone or, by cold treatment followed by incubation with thrombin at 37 degrees C. The amount of increase in uptake and binding produced by thrombin was independent of both thrombin (1--5 Units/10(9) platelets) and colchicine concentrations (1--50 X 10(-6) M). It is postulated that thrombin may initiate the formation, or make available, colchicine binding sites (microtubule subunits) within platelets.

Blood Platelets↗