experiment 10 units of PC were pooled and divided into two equal parts. One part was warmed before transfusion and the other part was transfused at ambient temperature. Each patient received both parts in random order, with a 4 h interval between the two transfusions. The corrected count increment (CCI) was calculated from the pre-transfusion and post-transfusion platelet counts obtained 10 min and 60 min after transfusion; CCI = patient’s platelet count increment (109) x body surface area (m2)fnumber of platelets transfused (1011). each
Odds ratios (with 95%CI)for individual risk factors for invasive and non-invasive melanoma cases. Odds are relative to the non-melanoma LLNLpopulation with OR set equal to 1 0.
melanomas were 1 ’5 for either risk factor (p > 0-10). The difference between the ORs for invasive compared with non-invasive melanomas is significant for eye colour (p 0-004) and of borderline significance for dysplastic moles (p = 0075) and large moles (p=0067). These results should be tested in populations with larger numbers of invasive and non-invasive melanoma. Invasive and in-situ cases did not differ with respect to demographic characteristics (age, sex, or educational achievement) or sick leave. If confirmed, these fmdings suggest that traditional risk factors for melanoma may represent promotion factors or an inability to provide effective local control of these lesions in susceptible people. Melanoma initiators may be fairly common (eg, exposure to ultraviolet light in childhood) and lead to early-stage, nonmetastatic lesions that are detected with greater frequency as awareness increases. Promoters may be much less common, leading to the observed widening discrepancy between melanoma incidence and melanoma mortality. =
This work was done under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract W-7405-Eng-48. Lawrence Livermore National Laboratory, Livermore, California 94550, USA
DAN H. MOORE
Permanente Medical Group, San Rafael, California
JEFFREY S. SCHNEIDER
University of California, San Francisco, California
RICHARD W. SAGEBIEL
1. Austin DF, Reynolds PJ, Snyder MA, et al. Malignant melanoma among employees of Lawrence Livermore National Laboratory. Lancet 1981; ii: 712-16. 2. Beral V, Evans S, Shaw H, et al. Cutaneous factors related to the nsk of malignant melanoma. Br J Dermatol 1983; 109: 165-72. 3. Elwood JM, Gallagher RP, Hill GB, et al. Pigmentation and skin reaction to sun as risk factors for cutaneous melanoma: Western Canada Melanoma Study. Br Med J 1984; 288: 99-102. 4. MacKie RM, Freudenberger T, Aitchison TC. Personal nsk-factor chart for cutaneous melanoma. Lancet 1989; ii 487-90.
Beneficial effect of pre-transfusion warming of platelets prepared from buffy coats
SiR,—Hutchinson et all showed that incubating stored platelet concentrates (PC) at 37°C just before transfusion had a beneficial effect on the post-transfusion increment in platelet count. This observation was made in children with stable thrombocytopenia, and platelets were harvested from platelet-rich plasma. We have investigated in 9 adults the effect of incubating, at 37°C for 1 h immediately before transfusion, leucocyte-poor PC from buffy coats2 that had been stored for 3-5 days at 22°C with gentle agitation. All patients were being treated for acute myeloid leukaemia and had stable thrombocytopenia-ie, no sepsis, splenomegaly, fever, excessive bleeding, or disseminated intravascular clotting and no signs of refractoriness to platelets. For
CCIs 10 min and 60 min after transfusion
(SE 1-0) and 8-6 (1-5), respectively, for non-warmed platelets, and 13-8 (1-6) and 12(2-0), respectively, for warmed platelets. Thus, the CCI was 44% higher (p < 0-005) at 10 min post-transfusion and 33% higher (p < 0-025) 60 min post-transfusion when platelets had been warmed than when they had been transfused without previous incubation. The observation that a difference was already present 10 min after transfusion suggests that the immediate clearance of platelets in the patient is reduced by incubation at 37°C. This increase in platelet survival is probably associated with our observationthat platelet shape may change from spherical to disc-like with warming at 37°C. Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam, Netherlands Red Cross Blood Bank Amsterdam
R. FIJNHEER R. N. I. PIETERSZ
Department of Haematology, Free University Hospital, Amsterdam
P. C. HUIJGENS
Central Laboratory of the Netherlands Red Cross Blood Transfusion Service
D. DE KORTE D. Roos
Red Cross Blood Bank, Postbus 9137, 1006 AC Amsterdam, Netherlands
H. W. REESINK
1. Hutchinson RE, Schell MJ, Nelson EJ, et al. Beneficial effect of brief pre-transfusion incubation of platelets at 37°C. Lancet 1989; i: 986-88 2. Pietersz RNI, Reesmk HW, Dekker WJA, Fijen FJ. Preparation of leukocyte-poor platelet concentrates from buffy coats. Special inserts for centrifuge cups. Vox Sang 3.
1987; 53: 203-07. Fijnheer R, Pietersz RNI, de Korte D, Roos D. Monitoring of platelet morphology during storage of platelet concentrates. Transfusion 1989; 29: 36-40.
IgM detection in
SIR,-Dr Wunderli and colleagues (April 28, p 1042) report a pregnancy in which, although there was no history of rubella exposure or illness, termination was done on the basis of high rubella IgG antibodies with a positive IgM test. IgM antibodies were present to a number of different viral antigens for which they and we have no explanation. We agree with Wunderli and colleagues that the decision to terminate was unjustified, but on different grounds. We know that in subclinical rubella or reinfections, IgM antibody is low or absent, that babies are rarely affected/-3 and that specific IgM antibody can persist for 1 year or longer after natural or vaccine infections.’ Wunderli et al give no assessment of whether the rubella IgM antibody concentrations were weakly, moderately, or strongly positive. This situation points to the need for an international standard for rubella IgM antibody and to the fact that the level of IgM antibody is crucial in the assessment of the need for further
laboratory investigations (eg, sucrose density fractionation, specific Epstein-Barr virus tests) before any clinical decisions are made. The rationale for doing the IgM antibody test is not clear in this case. In the absence of any clinical indication we assume that Wunderli and colleagues, on finding high IgG antibodies in antenatal sera, routinely test for IgM antibody. This practice was discussed in your correspondence columns in 19825 and we still believe that, in the context of rubella, a policy of laboratory initiated IgM antibody tests in the absence of a clinical indication can lead to unnecessary terminations. The management of rubella problems in pregnancy would be served best by medical education rather than by such application of additional laboratory testing. "Clinical virologists should ensure