Lead Poisoning
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Lead Poisoning ASSOCIATION WITH HEMOLYTIC ANEMIA, BASOPHILIC STIPPLING, ERYTHROCYTE PYRIMIDINE 5'-NUCLEOTIDASE DEFICIENCY, AND INTRAERYTHROCYTIC ACCUMULATION OF PYRIMIDINES WILLIAM N. VALENTINE, DONALD E. PAGLIA, KAY FINK, and GLENN MADOKORO From the Departments of Medicine and Pathology, University of California, Center for the Health Sciences, Los Angeles, California 90024 and the Wadsworth General Hospital, Veterans Administration Center, Los Angeles, California 90073 A B S T R A C T Lead intoxication is accompanied by an specific 5'-nucleotidase (E.C.3. 1.3.5.) present in eryth- acquired deficiency of erythrocyte pyrimidine-specific, rocytes but not yet demonstrated in other tissues (1, 2). 5'-nucleotidase. Genetically determined deficiency of this The syndrome is associated with a marked degree of enzyme is associated with chronic hemolysis, marked basophilic stippling on the stained blood film and with basophilic stippling of erythrocytes on stained blood large intraerythrocytic accumulations of nucleotides. films, and unique intraerythrocytic accumulations of About 80c% of the latter are eitlher cytidine or uridine, pyrimidine-containing nucleotides. The present report with cytidine predominating. Pyrimidine nucleotides, documents that lead-induced deficiency when sufficiently when detected at all, are present in only minute amounts severe gives rise to findings similar to the hereditary in normal erythrocytes (3-11). Nucleotidase-deficient disorder. Whereas pyrimidine-containing nucleotides are cells are unable to dephosphorylate, and thus render virtually absent in the erythrocytes of normal and reticu- diffusible, the pyrimidine 5'-nucleoside monophosphates locyte-rich blood, 12% of erythrocyte nucleotides in the which result from degradation of ribosomal RNA by blood of a patient with lead intoxication contained cyti- ribonucleases as the reticulocyte matures (1). The ac- dine. Nucleotidase activity was about 25% that in nor- cumulated pyrimidine nucleotides are believed to retard mal erythrocytes and 15% or less of that expected in RNA breakdown (1) with resulting aggregations of comparable reticulocyte-rich blood. The distribution of undegradecl and partially degraded ribosomes giving rise nucleotidase activity in patient erythrocytes is unknown. to basophilic stippling as their morphologic counterpart. and much more severe deficiency could have been present We have recently presented data indicating that the py- in subsets of the cell populations analyzed. The findings rimidine 5'-nucleotidase of normal erythrocytes is mark- indicate that the hemolytic anemia and increased baso- edly inhibited in vitro by low concentrations of lead and philic stippling characteristic of certain cases of lead certain other heavy metals, and that lead overburden in intoxication may share a common etiology with essen- man in vivo is associated with substantial and sometimes tially identical features of the genetically determined very marked reductions in the erythrocyte nucleotidase disorder. activity (12). While the erythrocytes of 15 subjects with documented lead overburden exhibited nucleotidase INTRODUCTION activity ranging from 11 to 70% and averaging about 40%C of normal, only one exhibited anemia, and this was Hereditary hemolytic anemia occurs in association with mild. In none was basophilic stippling prominent on the a severe genetically determined deficiency of pyrimidine- stained blood film. In these subjects it was not possible to demonstrate significant accumulations of pyrimidine Received for publication 2 January 1976 and ini revised nucleotides within the erythrocytes. It was postulated, form 17 May 1976. however, that the lead-induced nucleotidase deficiency, 926 The Journal of Clinical Investigation Volume 58 October 1976 926-932 TABLE I Hemotologsc Findings before, during, and after Admission for Lead Intoxication Basophilic Date WBC RBC Hb PCV MCV MCH MCHC Retics. stippling XJ103/;, X106/'I g/l1O ml % IU3 az % % 9 March 1972* 16.4 5.18 16.0 46.8 90.0 31.0 34.0 Normal 24 July 19751 7.4 3.74 10.4 32.1 83.0 27.6 33.0 + + + 20 November 1975§ 9.3 4.17 9.9 35.0 83.9 23.7 28.3 9.1-24 + + + + 30 January 197611 8.1 5.03 14.0 42.5 79.0 27.8 35.2 1.7 + 11 March 197611 7.6 5.08 14.2 41.0 81.0 27.8 34.8 0.8 + 10 May 197611 8.6 5.23 15.5 45.0 86.0 29.6 34.4 2.1 Normal Basophilic stippling was judged on Wright's stained peripheral blood films. Abbreviations: MCH, mean corpuscular hemoglobin; MCHC, mean corpuscular hemoglobin concentration; MCV, mean corpuscular volume; PCV, packed cell volume; RBC, erythrocytes; Retics., reticulocytes; WBC, leukocytes. * Admitted for perforated appendix. t Removal of ganglion cyst from finger. § Representative hemogram during admission for lead intoxication. 11 After last occupational exposure to lead which occurred about 11 November 1975. if sufficiently severe, should lead to hemolytic anemia, left ring finger had been removed surgically 24 July increased basophilic stippling, and accumulations of py- 1975. rimidine nucleotides in erythrocytes in a manner analo- Physical exantiationi. The positive findings consisted gous to that of the genetically determined deficiency. If of mild tenderness localized to the epigastrium, poor such were the case, lead-induced nucleotidase deficiency dental hygiene with a gray-blue discoloration compatible would represent one mechanism leading to the hemolytic vitli a so-called "lead line" on all of his gingiva, and anemia and prominent basophilic stippling long recog- orthostatic hypotension (blood pressure 135/90 supine nized as characteristic features of certain cases of severe to 85/45 erect). Neurological examination was within lead intoxication. The subject reported here had the normal limits. requisite hematologic features essential for testing the Hemiiatologic findintgs (Table I). The total and dif- hypothesis, and the following studies indicate that lead ferential leukocyte count and blood platelets were nor- intoxication and the hereditary disorder have in common mal. Moderately severe anemia with reticulocytosis rang- a hemolytic syndrome with very similar clinical, mor- ing from 9.5 to 24%, persisted during the week of hos- phological, and biochemical characteristics. pitalization. The erythrocytes on the stained blood film exhibited anisocytosis, moderate to marked hypochro- masia and polychromasia, and many erythrocytes were CASE REPORT coarsely or finely stippled (Fig. 1). A rare nucleated Present history. The patient, a 26-yr-old Mexican- erythrocyte was noted. The serum iron (87 Mg/100 ml) American spray painter, entered the hospital complain- and total iron binding capacity (278 Ag/lOO ml) were ing of 2 days of sharp, more or less constant epigastric normal. Bone marrow aspiration revealed a mildly hy- and back pain. On admission the latter had largely sub- percellular marrow with erythroid predominance and sided, but epigastric pain persisted and was accompanied abundant stainable iron. by anorexia, nausea, and vomiting. He denied aspirin X-ray studies. Upper gastrointestinal X rays showed ingestion, melena, hematemesis, ulcer disease, or prior a mild deformity of the duodenal bulb without ulcera- abdominal pain. He had worked as a spray painter for tion and probable paralytic ileus without evidence of 8 yr and for his present employer 9 mo. He denied intestinal obstruction. A barium enema and sigmoidos- knowledge of lead being a component of the paints he copy revealed no abnormality. An intravenous pyelogram had used during the last 3 yr. He was unaware of simi- was essentially normal. lar illness among co-workers or family members or of Other laboratory stu(dies. Other studies were unre- other potential exposures to lead-containing materials. markable, including serum electrolytes, creatinine, glu- He denied drinking or eating liquids or foods stored in cose, calcium, amylase. albumin and total protein, a va- glazed pottery. riety of liver function tests, and blood cortisone levels. Past history. Surgery had been performed for a per- The Coombs' antiglobulin test was negative. forated appendix in UCLA Hospital in March of 1972 Special studies for lead overburden (Table II). with an uneventful recovery. A ganglion cyst on the Blood and urine lead were markedly elevated as were Lead Poisoning, Nucleotidase Deficiency, Increased Red Cell Pyrimidines 927 method of Krimsky (23). Hemolysates prepared by freez- ing and thawing three times were dialyzed essentially free of endogenous phosphates and then assayed for pyrimidine 5'-nucleotidase activity as previously described (1, 2). The assays were performed at 37'C with 2.2 mM UMP or CMP as substrate at pH 7.4. Assays were made with and without addition of 0.010 ml of 0.1 M dithiothreitol (Cle- land's reagent, obtained from Calbiochem, San Diego, Calif.), a reducing agent affording protection to sensitive enzyme sulfhydryl groups. After deproteinization with trichoroacetic acid, inorganic phosphorus (Pi) liberated by the nucleo- tidase was assayed, and activity was expressed as micro- moles of Pi evolved per hour per gram of hemoglobin. The ultraviolet absorption spectra were determined at pH 2 and 12 on extracts of washed erythrocytes as previously de- scribed (1). All assays for blood and urinary lead, ALA, and copro- and uroporphyrins were obtained through the UCLA Hospital Clinical Laboratory. Specimens submitted for chromatographic analysis were prepared as follows. Erythrocyte suspensions in saline containing known numbers of cells and freed of leukocytes and platelets were frozen