1245

forming E-rosettes were estimated after overnight incubation on icewith sheep erythrocytes treated with 2-amino-ethylisothio-uronium bromide hydrobromide (AET) and numbered 73±6%

(mean±SD) of the cells present. Using the direct antiglobulinrosette method of Coombs et al .,3 we found that 18±4% of the cellshad surface immunoglobulin. This figure did not change after over-night incubation of cells at 37°C in 20% fetal calf serum and subse-quent washing with warm medium to remove cytophilic im-munoglobulin. Residual monocytes were identified by a-naphthylacetate esterase staining and numbered 3±3%. Thus 94±5% of

peripheral blood mononuclear cells were identifiable (as T, B, ormonocyte) by these three techniques.Are those few cells not identified necessarily "null" cells? Our

figures for B-cells are similar to those ofHaegert et al. and Dhaliwalet al. Thus we indirectly support Haegert’s demonstration that atleast 80% of non-E-rosetting cells which lack surface im-

munoglobulin by fluorescence and receptors for guineapig C3 butwhich do possess receptors for the Fc portion of IgG-the "L" cellsof Horwitz and colleagues 6,7 -do in fact have stable surface im-munoglobulin.8,9 Indeed Horwitz et al.10 have now shown thatabout a third of cells defined by Fc-receptor binding characteristicsare E-rosetting (T -) cells, thus reducing their prevalence of L cellsto a mean of 9% of cells present. In our series 24±6% of cells had low

avidity Fc receptors estimated by EA rosettes with bovine

erythrocytes highly sensitised with the IgG fraction of specific rab-bit antiserum. After overnight incubation to remove cytophilic im-munoglobulin this figure remained 23±6%. These Fc-receptor-bearing cells are readily accounted for by monocytes, T-cells withFc-receptors (mean of 7-10% of all cells as determined by ourselvesand others 1 I, using double markers), plus a proportion (at least40%) of B-cells as defined by rosetting. Thus the vast majority ofFc-receptor-bearing cells in human peripheral blood mononuclearpreparations can be shown to be of T, B, or monocyte lineage.Those cells (mean of 6% in our series) which cannot be confident-

ly and consistently identified in health may comprise activated(blast) cells which lose receptors or less mature cells whose densityof surface receptor is too low to be detected by the probes used. Thissituation is likely to be exaggerated in diseases where the immunesystem is primarily or secondarily involved. Bearing in mind thevarying avidity of conventional probes and the errors inherent insampling and counting cells from individuals of varying ages andimmune status, we feel that "failure" to identify all cells present isreasonable, and preferable to invoking the concept of "null" cells tomake the sum equal 100%.

M. L. C. is supported by the National Health and Medical Research Councilof Australia.

Clinical Immunology Division,Kennedy Institute of Rheumatology,London W6 7DW

MILTON L. COHENCHRISTINE PLATER-ZYBERKR. N. MAINI

2. Kaplan ME, Clark C. An improved rosetting assay for the detection of humanT-lymphocytes. J Immunol Methods 1974; 5: 131-35.

3. Coombs RRA, Wilson AB, Eremin O, Gurner BW, Haegert DG, Lawson YA, BrightS, Munro AJ. Comparison of the direct antiglobul in rosetting reaction with themixed antiglobulin rosetting reaction for the detection of immunoglobulin onlymphocytes. J Immunol Methods 1977; 18: 45-52.

4. Haegert DG, Hurd C, Coombs RRA. Comparison of the direct antiglobulin rosettingreaction with direct immuno-fluorescence in the detection of surface membrane im-

munoglobulin on human peripheral blood lymphocytes. Immunology 1978; 34:533-38.

5. Dhaliwal HS, Haeney MR, Ling NR. Are most "null" cells B cells? Lancet 1980; i:1092.

6. Lobo PI, Westervelt FB, Horwitz DA. Identification of two populations of

immunoglobulin-bearing lymphocytes in man. J Immunol 1975; 114: 116-19.7. Horwitz DA, Lobo PI. Characterization of two populations of human lymphocytes

bearing easily detectable surface immunoglobulin. J Clin Invest 1975; 56: 1464-72.8. Haegert DG. Demonstration of surface membrane immunoglobulin on L lymphocytes

by the mixed antiglobulin rosetting reaction (MARR) and the direct antiglobulinrosetting reaction (DARR). Immunology 1979; 38: 459-65.

9. Haegert DG. Are most "null" cells B cells’ Lancet 1980; ii: 308.10. Horwitz DA, Cooper M, Carvalho D. Binding characteristic of Fc-receptors for IgG on

human peripheral blood T lymphocytes and "L" lymphocytes. a technical report.Clin Immunol Immunopathol 1979; 14: 159-71.

11. Cnossen J, Lafever GJM, Damsteeg WJM, Meijer CJLM. Mixed rosette assay for thedetection of Tµ and T&ggr; lymphocytes. J Immunol Methods 1980; 36: 197-209.

HYPERKALAEMIA IN DRUG ADDICTS

SIR,-Dr Pearce and Dr Cox (Oct. 25, p. 923) describe dangerous-ly high plasma potassium levels after heroin overdosage. We alsohave observed severe hyperkalaemia in a drug addict.A 20-year-old man had been admitted to another hospital 2 days

before admission here because of heroin overdosage. (He had beentreated with naloxone and discharged himself after 24 h againstmedical advice.) About 18 h before admission to our hospital he in-gested at least 70 mg methadone and was found comatose with smallpupils, cyanosis, and shallow, irregular respirations. Systolic bloodpressure was palpable at 60 mm Hg, heart rate 60 /min regular, cen-tral venous pressure not raised. He had on the lateral aspect of hisleft thigh a 3 cm erythematous lesion. He was treated with 0-4 4 mgnaloxone intravenously, oxygen by’mask, and plasma infusions, andhe gradually regained consciousness with improvement of respira-tion and circulation. Laboratory results showed a severe

hyperkalaemia (table) and lacticacidosis (pH 7-14, lactate 8-6 6

mmol/1).

LABORATORY FINDINGS

The ECG showed an idioventricular rhythm with wide QRS com-plexes (0’ 20 s) and bizarre ST-T configurations.Treatment was immediately started with glucose 40% containing

12 U regular insulin per 100 ml, 4 2% sodium bicarbonate, and 10ml 10% calcium gluconate. The serum potassium fell to safe levelsover 5 h and the ECG reverted to normal.A few hours after the start of volume loading pulmonary oedema

developed, which improved after frusemide 40 mg intravenouslyand discontinuation of the infusion. On the second day a large pain-ful swelling in the right gluteus maximus and the region of the rightthigh with a red-bluish discolouration of the skin appeared.Also, a painful swelling in the left masseter muscle and an increaseof the erythematous lesion present on admission with swelling of theunderlying muscles was noticed. The peripheral pulses remainedpalpable. In combination with the extremely high serum creatinephosphokinase and transaminase levels (table) these swellings wereinterpreted as muscle necrosis. No history of trauma could be ob-tained. In the following week progressive renal insufficiencynecessitated haemodialysis.In this case injury to muscle together with moderately severe

acidosis and renal insufficiency might account for the severe

hyperkalaemia. We believe that this muscle injury was the result ofa acombination of factors: hypoperfusion, hypoxaemia, compression,and, possibly direct toxic effects of methadone (and/or heroin?).From the urine only methadone could be recovered. It remainspossible, however, that the heroin overdosage 2 days before admis-sion was the actual noxious event.In the course of weeks all physical abnormalities disappeared and

all laboratory values returned to normal. The patient fullyrecovered from his acute renal failure. No physical signs of muscleinjury were present on admission, as in the patient described byPearce and Cox; we support their suggestion that serum electrolytesbe routinely measured in severe opiate overdosage cases.

Medical Intensive Care Unit,Free University Hospital,1007 MB Amsterdam, Netherlands

L. G. THIJSE. BALKW. BRONSVELD

J. C. THIJS