Correspondence 49 5 interstitial deletion of long arm of chromosome 9 is a non- random chromosomal abnormality, and that this abnor- mality can be a primary event associated with a particular

REFERENCES

Bennett, J.M.. Catovsky, D., Daniel, M.T., Flandrin. G., Galton, D.A.G.. Gralnick. H.R. & Sultan, C. (FAB Cooperative Group)

subtype of AML.

Clinique Medicale, Service de Professeur Jacques Debray, Hbpital Suint-Antoine, 184 Rue de Faubourg Saint-Antoine, 7 5 5 7 1 Paris Cedex 12. France

(1976) Proposals for the classification of acute leukaemia. British Journal ojHaematology. 33, 451458.

Hoyle. C., Sherrington. P.D. & Hayhoe F.G.J. (1987) Cytological features of 9q- deletions in AML. British Journal of Haematology.

Kao, Y.S.. Sartin, B.W., Van Brunt, J. & Hew A.Y.K. (1986) Interstitial 9q deletion (91 2q22) in two cases of acute myeloblastic leukemia. Cancer Genetics and Cytogenetics, 19, 365-366.

Mecucci. C., Vermaelen, K., Kulling, G.. Michaux, J.L., Noens, L., Van Hove, W., Tricot, G., Louwagie, A. & Van Den Berghe, H. (1984) Interstitial 9q - deletions in hematologic malignancies. Cancer Genetics and Cytogenetics, 12, 309-319.

NICOLE SMADJA MARCEL KRULIK

GUSTAVO GONZALEZ CANALI J. DEBRAY

AIMERY DE GRAMONT 66, 277-278.

MONOCLONAL ANTIBODY Ki-6 7 AS A PROLIFERATION MARKER

The article by Pileri et a1 (1987) provides interesting data on measuring proliferation kinetics in human cell lines as well as in cryostat sections. However, we have come up against some limitations in the use of the monoclonal antibody Ki-67 as a proliferation marker.

Using the three-stage APAAP-technique (Cordell et al, 1984) we were unable to demonstrate reactivity of exponen- tially growing DAUDI cells with Ki-67 (Dianova, Hamburg, F.R.G., dilution 1 : 10) in cytospin preparations stored at -20OC for longer than 2 weeks, whereas freshly prepared cytospin preparations showed 70% of the DAUDI cells as being positive with Ki-67. The fixation was in keeping with that used by the authors (10 min acetone).

The instability of the Ki-67 antigen should be taken into consideration when using Ki-67 as a proliferation marker in stored cytospin preparations.

REFERENCES

Cordell, J.L., Falini, B, Erber, W.N., Ghosh, K.A.. Zainalabideen. A., MacDonald, S.. Pulford, K.A.F.. Stein, H. & Mason, D.Y. (1984) Immunoenzymatic labeling of monoclonal antibodies using immune complexes of alkaline phosphatase and monoclonal anti- alkaline phosphatase (APAAP complexes). Journal of Histo- chemistry and Cytochemistry, 32 , 21 9-229.

Pileri, S., Gerdes. J., Rivano. M.. Tazzari, P.L.. Magnani. M., Gobbi, M. &Stein, H. (198 7) Immunohistochemical determination of growth fractions in human permanent cell lines and lymphoid tumours: a critical comparison of the monoclonal antibodies OKT9 and Ki-67. British Journal of Haematology. 6 5 , 271-276.

Abteilung h e r e Medizin, ANDREAS NEUBAUER Klinikurn Charlottenburg, D. HUHN Spandauer Darnrn 130, Dl000 Berlin, F.R.G.

FLOW CYTOCHEMICAL PATTERNS OF WHITE BLOOD CELLS IN HUMAN HAEMATOPOIETIC MALIGNANCIES

In the article by Drewinko et al (1987) we met the phrase: ‘Our primitive attempts to introduce automated machine- assisted criteria in the diagnosis and follow-up of patients with acute leukaemia must by necessity be met with utmost opposition by traditional haematologic morphologists’ (page 3 5 ) . Besides Macchiavelli, our article from 1984 was also cited, to illustrate the foregoing sentence (Drewinko et al, 1987). However, it is obvious that the authors have either not read our article, or have not fully understood it.

In 1984 we published our results with regard to our investigations with the Hemalog D in children with acute lymphoblastic leukaemia (ALL) and disseminated non-Hodg- kin lymphoma (NHL). We concluded that the manual count is superior to the Hemalog D count with regard to the recognition of lymphoblasts in children with ALL and disseminated NHL. The lymphoblasts in childhood ALL are predominantly of the FAB-type L I , from which the cell size does not differ significantly from those of normal lympho-

cytes. Therefore these cells, which are hidden among the lymphocyte population, are mainly counted as lymphocytes by the Hemalog D. In these cases the Hemalog D appears to be unreliable in detecting those lymphoblasts which can, on the other hand, be easily recognized by light microscopy. This finding does not reflect conservatism but it is a result of an investigation.

Far from being traditional haematologists, our group was among the first to introduce automated cytochemistry in Western Europe. Our study showed that the Hemalog D could not completely replace the human naked eye. The citation by Dr Drewinko et al (read: Technicon Inc.) was therefore not correct.

H.BEHRENDT A. H. VAN GENNIP N. G. G. M. ABELING E. CRANENDONK A. VAN ERVEN

Emma Kinderziekenhuis, Spinozastraat 51, 1018 HJ Amsterdam, The Netherlands