Function of Drosophila ovo+ in germ-line sex determination depends on X-chromosome number

Germ-line sex determination in Drosophila melanogaster requires an assessment of the number of X chromosomes as measured against autosomal standards (XX = female, X = male) and signaling from the soma. Both of these sex determination cues are required for female-specific Sex-lethal+ function in germ cells. The ovo+ locus encodes zinc finger protein(s) required for female-specific splicing of Sex-lethal+ pre-mRNA, making ovo+ a candidate function acting between the two principal cues and Sex-lethal+. We have made ovo reporter genes and find that they show high activity in the germ line of females and low activity in the germ line of males. XY flies transformed into somatic females do not show high levels of reporter activity, while XX flies transformed into somatic males do. This shows that high level ovo+ expression depends on the number of X chromosomes, not the somatic sexual signals. The requirement for ovo+ function is restricted to XX flies. Mutations in ovo have no effect on XY males, X0 males or XY females, but have pronounced effects on germ cell viability in XX females, XX females with sex transformed germ lines, and XX males indicating that ovo+ gene products are required for events occurring only in flies with two X chromosomes.

A simple portable ocular light device for phototherapy of seasonal affective disorder

The authors report the development and a safety and acceptability study of a portable ocular light device, the SADlite. The study was conducted in 15 adult patients who had seasonal affective disorder (SAD). Each patient was given three two-week "on" phototherapy periods alternating with three two-week "off" periods. The SADlite provides 8,000 lux. Thirteen (13) of the 15 patients were completers and, as a group, achieved impressive clinical and statistically significant improvement (p < 0.0001) on three standard outcome measures. The SADlite was well tolerated, produced no adverse visual effect, and was preferred by patients previously exposed to stationary phototherapy devices.

Phase I study of recombinant human interleukin-1 beta (rhIL-1 beta) in patients with bone marrow failure

The administration of recombinant human interleukin-1 beta (rhIL-1 beta) stimulates pluripotent cell growth and reduces mortality from infection in animal models. In this phase I trial, rhIL-1 beta (0.02-0.50 microgram/kg) was administered by 30-minute intravenous infusion once daily for 2 or 5 consecutive days. The dose was escalated with the subsequent cycle in the same patient if no hematologic response was observed. Nineteen patients with severe bone marrow failure received 60 courses of IL-1 beta. Diagnoses included autologous bone marrow transplant (BMT) (n = 5), allogeneic BMT (n = 7) or idiopathic aplastic anemia (n = 6) and 1 patient with chronic myeloid leukemia. Toxicities included fever (89%), chills (85%), hypertension (89%), hypotension (57%) and headache (95%). No complications were life-threatening and all either spontaneously resolved or were managed pharmacologically. In 8 of 19 patients there was an acute, transient increase in neutrophil counts. In 2 patients there was a transient increase in platelet count; however, no durable, clinically significant effects on peripheral blood counts were observed. In conclusion, administration of rhIL-1 beta in this population of patients had limited efficacy and moderate toxicity.

The role of the plasma from platelet concentrates in transfusion reactions

BACKGROUND

Febrile, nonhemolytic transfusion reactions are the most frequent adverse reactions to platelets. A number of observations argue against the widely held view that these reactions result from the interaction between antileukocyte antibodies in the recipient and leukocytes in the platelet product. We sought to determine whether substances in the plasma or the cells in the product cause reactions to transfused platelets.

METHODS

We separated standard platelet concentrates into their plasma and cellular components and then transfused both portions in random order. Patients were monitored for reactions during all transfusions. Before each transfusion, the concentration of cytokines (interleukin-1 beta and interleukin-6) was measured in the platelet products. Studies were also performed on the platelet products to determine the effect of storage on the concentration of cytokines.

RESULTS

Sixty-four pairs of platelet-product components (the plasma supernatant and the cells) were administered to 12 patients. There were 20 reactions to the plasma supernatant and 6 reactions to the cells (chi-square = 6.50, P = 0.009). Eight transfusions were associated with reactions to both products. The plasma component was more likely to cause severe reactions than the cells (chi-square = 9.6, P < 0.01). A strong positive correlation was observed between the reactions and the concentration of interleukin-1 beta and interleukin-6 in the plasma supernatant (P < 0.001 and P = 0.034, respectively). In vitro studies demonstrated that interleukin-1 beta and interleukin-6 concentrations rise progressively in stored platelets and that these concentrations are related to the leukocyte count in the platelet product.

CONCLUSIONS

Bioreactive substances in the plasma supernatant of the platelet product cause most febrile reactions associated with platelet transfusions. Removing the plasma supernatant before transfusion can minimize or prevent these reactions.

A comparison of artificial saliva and pilocarpine in radiation-induced xerostomia

Twenty patients with radiation-induced xerostomia were entered into a prospective randomized crossover study comparing a mucin-based artificial saliva (Saliva Orthana) and a mouthwash containing pilocarpine (5 mg three times a day). Overall the patients found that the pilocarpine mouthwash was more effective than the artificial saliva in relieving their symptoms (p = 0.04), and 47 per cent of the patients wanted to continue with this treatment after the study had finished.

Amphetamine-metabolites of deprenyl involved in protection against neurotoxicity induced by MPTP and 2'-methyl-MPTP

The ability of 1-deprenyl to protect against the parkinsonian effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been attributed to the inhibition of conversion of MPTP to MPP+ (1-methyl-4-phenylpyridinium) catalyzed by MAO-B. We report here that deprenyl-treatment in mice has an additional neuroprotective element associated with the rapid metabolization of 1-deprenyl to 1-methamphetamine and 1-amphetamine. 1-Methamphetamine and 1-amphetamine inhibit MPP(+)-uptake into striatal synaptosomes prepared from rats. Post-treatment by 1-deprenyl, 1-methamphetamine, 1-amphetamine (at times when MPTP is no longer present in the striatum of mice) protects against neurotoxicity in C57BL mice by blocking the uptake of MPP+ into dopaminergic neurons, and even against the neurotoxicity induced by 2'CH3-MPTP, which is partly bioactivated by MAO-A. These findings may have clinical implications since deprenyl has recently been found to delay the progression of Parkinson's disease.

Inadequate treatment of pain in ambulatory HIV patients

OBJECTIVE

To evaluate the prevalence of pain, how pain affects patients' lives, what treatments are being used, and the effectiveness of these pain treatments in ambulatory patients with human immunodeficiency virus (HIV) disease.

DESIGN

A self-administered pain survey (modified version of the Wisconsin Brief Pain Questionnaire).

SETTING

An ambulatory infectious disease clinic that deals mainly with ambulatory HIV patients.

PATIENTS

Ambulatory HIV patients.

OUTCOME MEASURES

Results of the response to the questionnaire.

RESULTS

Eighty-two of 148 patients surveyed had pain due to their disease in the month prior to completing the survey. Of those reporting pain, 60-70% reported that their pain interfered with aspects of their daily lives from a moderate to severe degree. In patients with pain, 40% reported that they were not receiving any pain treatment. Those patients who were receiving treatment only obtained a mean pain relief of 65%.

CONCLUSIONS

Pain is an important problem in terms of its prevalence and impact on patients with HIV disease. Pain control in this patient population is inadequate. Clinicians should realize that pain can be present regardless of the duration of the disease and its severity. Patients need to be educated about the proper use of pain medications and helped to understand that pain medications will not "worsen their disease."

Long-term follow-up of patients with invasive fungal disease who received adjunctive therapy with recombinant human macrophage colony-stimulating factor

Mortality of bone marrow transplant (BMT) patients who develop invasive fungal infection is greater than 80%. Long-term follow-up of 46 consecutive BMT patients who received recombinant human macrophage colony-stimulating factor (rhM-CSF) as adjunctive therapy with standard antifungal treatment who were entered into phase I/II trials at The Fred Hutchinson Cancer Research Center is reported. rhM-CSF (100 micrograms/m2 to 2,000 micrograms/m2; Chiron/Cetus Corporation, Emeryville, CA) was administered from day 0 to 28 after determination of progressive fungal disease. Results of long-term follow-up of fungal infection, relapse, and survival were compared with 58 similar historical controls. Multivariable analysis of the patients who received rhM-CSF showed two factors that significantly correlated with poor survival: Karnofsky score < or = 20% and Aspergillus infection. Overall, survival of patients who received rhM-CSF was greater than that of historical patients (27% v 5%) and was entirely because of a 50% survival rate in patients with Candida infection and Karnofsky scores greater than 20%. Prospective, randomized, controlled trials to determine efficiency of rhM-CSF are indicated and should be directed at patients with invasive candidiasis.

Recombinant granulocyte-macrophage colony stimulating factor followed by immunosuppressive therapy for aplastic anaemia

Seventeen patients with aplastic anaemia were treated with recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) for 14 d. Nonresponding patients were then treated with anti-human thymocyte globulin (ATG), methylprednisolone and oxymetholone. Side-effects of rhGM-CSF included fever, nausea and vomiting, diarrhoea, bone pain, headache and chills. Two patients had sustained trilineage haemopoietic recovery after receiving only rhGM-CSF. Of 11 patients who received immunosuppressive therapy, there was one complete response, two partial responses, one minimal response, and seven nonresponses. Actuarial survival at 2 years is 64%. Early administration of rhGM-CSF had no apparent effect on subsequent response to immunosuppressive therapy.

A simple multiple system organ failure scoring system predicts mortality of patients who have sepsis syndrome

A simple multiple system organ failure (MSOF) score may predict mortality of patients who have sepsis syndrome. Using an MSOF scoring system, we prospectively determined the presence or absence of respiratory, cardiovascular, renal, hepatic, gastrointestinal, hematologic, and neurologic organ failure on day 1 of sepsis syndrome in 154 consecutive patients who had sepsis syndrome in the ICU of a tertiary care, teaching hospital. We used 30-day hospital mortality as the primary outcome variable. Overall 30-day mortality was 34 percent. There was a strong linear association between number of organ system failures and 30-day mortality (p < 0.0001). Mortality was 20 percent in patients who had less than 3 organ system failures (n = 111) and 70 percent in patients who had 3 or more organ system failures (n = 43). Survival was assessed using the Cox proportional hazards model and was found to be significantly different (p < 0.01) between the two groups defined by the aforementioned dichotomy after adjustment for age and sex using time to death as the primary outcome. The increase in relative risk of death associated with 3 or more organ system failures was 2.77 (95 percent confidence interval, 2.74 to 2.83). Using logistic regression, the adjusted odds ratios (OR) for covariates most predictive of mortality were hematologic (OR = 6.2), neurologic (OR = 4.4), hepatic (OR = 3.4), cardiovascular (OR = 2.6), and age (1.05 per year). The logistic model using the seven organ system failures and age as covariates accurately predicted outcome 75 percent of the time with a sensitivity of 51 percent and specificity of 87 percent. In conclusion, a simple scoring system tabulating the number of organ system failures present on day 1 of sepsis syndrome predicts the mortality of patients who have sepsis syndrome with reasonable accuracy.

High-dose cyclophosphamide, carmustine, and etoposide followed by autologous bone marrow transplantation in patients with lymphoid malignancies who have received dose-limiting radiation therapy

PURPOSE

To evaluate high-dose chemotherapy followed by autologous bone marrow transplantation (ABMT) in patients with lymphoid malignancy who had received prior radiation therapy.

PATIENTS AND METHODS

Fifty-seven patients with non-Hodgkin's lymphoma (NHL; n = 23), Hodgkin's disease (HD, n = 32), or acute lymphoblastic leukemia (ALL; n = 2) with a history of previous radiation therapy were treated with cyclophosphamide (Cy; 7.2 g/m2), carmustine (300 mg/m2 or 600 mg/m2), and etoposide (2,400 mg/m2) (CBV) followed by ABMT.

RESULTS

The projected 2-year probabilities of survival, event-free survival (EFS), and relapse were .31, .24, and .76, respectively. For patients with intermediate- and high-grade lymphoma and HD the probabilities were .27, .10, and .14 for EFS and .57, .90, and .77 for relapse. The probability of nonrelapse mortality in the first 100 days post-ABMT was 33%. Idiopathic pneumonia syndrome (IPS) was observed in no patients who received carmustine 300 mg/m2 and 23% of patients who received carmustine 600 mg/m2 (P = .05). Eight-three percent of patients who received mediastinal radiation therapy less than 3 months before transplant developed IPS, compared with 13% who received radiation therapy more than 3 months before transplant (P = .001).

CONCLUSION

ABMT following high-dose CBV resulted in long-term disease-free survival in 25% of patients with lymphoid malignancies who had previously received dose-limiting radiation therapy. Fatal IPS and a high relapse rate were major factors limiting successful outcome following ABMT. The morbidity and mortality rates associated with the administration of carmustine 600 mg/m2 were prohibitively high, especially in patients who received mediastinal radiation immediately before ABMT, and were not associated with a decrease in post-ABMT relapse.

Topics and signs: defensive control of emotional expression

This single-case study examined frank disclosure of important topics in a brief exploratory psychotherapy, including topics closely related to a recent, unintegrated stressor life event. Quantitative measures of emotion and control variables showed heightened levels of both emotionally and defensive control during discourse on the topic of the stressor event. In future studies, such measures of verbal and nonverbal signs of emotional expression and defensive control might be used to identify topics in an unresolved state.

Autologous transplantation with peripheral blood mononuclear cells collected after administration of recombinant granulocyte stimulating factor

Peripheral blood mononuclear cells (PBMC) were collected after the administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and used as the sole source of hematopoietic stem cells after myeloablative therapy with busulfan (Bu) and cyclophosphamide (Cy). These studies were performed in 12 patients with malignancies (4 non-Hodgkin's lymphoma, 5 breast cancer, 1 testicular carcinoma, 1 Wilm's tumor, and 1 undifferentiated carcinoma) who had bone or bone marrow disease or had low marrow cellularity. rhG-CSF (16 micrograms/kg/d) was administered for 5 to 7 days by subcutaneous injection and PBMC were collected for 2 to 5 days beginning on day 4 after initiation of rhG-CSF, using continuous-flow blood-cell separators that processed 10 to 12 L of whole blood. From a median of three collections, a mean of 24.0 x 10(8) (+/- 10.5 SD) total nucleated cells/kg containing 12.6 x 10(8) (+/- 4.5 SD) mononuclear cells/kg, 7.3 x 10(6) (+/- 4.3 SD) CD34+ cells/kg and 20.5 x 10(4) (+/- 28.1 SD) granulocyte-macrophage colony-forming units (CFU-GM)/kg were harvested and cryopreserved. After the administration of Bu 14 to 17 mg/kg and Cy 120 to 150 mg/kg, PBMC were thawed and infused. One patient received rhG-CSF after the infusion of PBMC and the remaining 11 patients did not receive postinfusion growth factors. Mean days to recovery of neutrophil levels of 0.1, 0.5, and 1.0 x 10(9)/L were 11.4 (range, 9 to 13), 12.7 (range, 10 to 15), and 13.6 (range, 11 to 16) and the mean day to platelet transfusion independence was 13.3 (range, 7 to 49). Time to recovery of neutrophils to 0.5 and 1.0 x 10(9)/L and platelets to 20 x 10(9)/L was more rapid than in historical patients treated with Bu and Cy who received marrow alone or marrow followed by the posttransplant administration of rh-G or GM-CSF. No graft failures have been observed with a follow-up of 4 to 12 months. These results indicate that PBMC collected after rhG-CSF lead to rapid hematopoietic recovery after myeloablative chemotherapy.

The plastocyanin-deficient phenotype of Chlamydomonas reinhardtii Ac-208 results from a frame-shift mutation in the nuclear gene encoding preapoplastocyanin

Ac-208 is a plastocyanin-deficient mutant of Chlamydomonas reinhardtii that contains only 2-3% of the wild-type level of plastocyanin-encoding mRNA and no detectable plastocyanin. Sequence analysis of the ac-208 plastocyanin-encoding gene reveals a single nucleotide insertion in the first exon compared with the wild-type gene; this alters the reading frame and results in a premature nonsense codon. We have introduced the genomic sequence encoding plastocyanin from a wild-type strain into ac-208 by cotransformation with a selectable marker encoding nitrate reductase. Of 22 nit+ transformants characterized, nine contained additional plastocyanin-encoding sequences (compared with untransformed cells) and each of these nine transformants was found to accumulate the protein. Transformants that do not contain newly introduced plastocyanin sequences retain the plastocyanin-deficient phenotype. The introduced plastocyanin-encoding sequences are stable during mitotic growth in liquid culture over a period of several months, as is expression from the introduced sequences. We suggest that the decreased steady state level of plastocyanin-encoding messages is a consequence of the frame-shift mutation in the structural gene. The ability to complement ac-208 with plastocyanin-encoding sequences will allow the introduction and analysis of in vitro mutagenized plastocyanin sequences in vivo in transgenic C. reinhardtii cells.

Neonatal psoas pyomyositis simulating pyarthrosis of the hip

Osteomyelitis with concomitant pyarthrosis or isolated pyarthrosis heads the differential list for a newborn with limb disuse and a flexion deformity of the hip. The diagnosis of psoas abscess, a primary suppurative myositis, should additionally be entertained. Stronger consideration should be given to this clinical entity after pyarthrosis of the hip has been excluded by an arthrocentesis performed under fluoroscopy. Radiologic imaging may facilitate the diagnosis. A blood culture may yield the organism responsible for the skeletal muscle abscess, even in nontoxic patients.

Clinical correlates of in vitro HIV-1 resistance ot zidovudine. Results of the Multicentre Canadian AZT Trial

OBJECTIVE

To describe the rate of development of in vitro HIV resistance to zidovudine (ZDV) and its prognostic implications within the Multicentre Canadian AZT Trial (MCAT).

METHODS

HIV-infected subjects in Centers for Disease Control (CDC) stages IIB, III and IVC-2 with CD4 cell counts > 270 x 10(6)/l were treated with ZDV as part of a dose-range study. Participating volunteers underwent prospective clinical and laboratory evaluations at regular intervals. Viral cultures and sensitivity testing were performed every 12 weeks in a predefined subset of 50 volunteers. An isolate was designated ZDV-resistant if it had a median inhibitory concentration (IC50) for ZDV at least 50-fold higher than that of virus isolated from the same subject before initiation of antiviral chemotherapy. The relationship between resistance and subsequent disease progression was studied using the Mantel and Byar method, for which, at each instance of disease progression, 2 x 2 tables classifying progression versus resistance status were constructed. The observed number of progressions was compared with that expected under the null hypothesis using Mantel-Haenszel methods adjusted for baseline CD4:CD8 ratio.

RESULTS

The Kaplan-Meier estimate for the cumulative development of in vitro resistance was 64% [95% confidence interval (CI), 41-78] at 180 weeks. Baseline CD4:CD8 ratio was negatively associated (P = 0.10) with the subsequent development of resistance (proportional hazard, 0.44; 95% CI, 0.17-1.10). After adjusting for baseline CD4:CD8 ratio, the numbers of observed and expected progressions following the development of resistance were 15 and 7.6, respectively (P = 0.008). A similar relative risk of progression between resistant and non-resistant states was found in the two CD4:CD8 strata; observed and expected progressions were 4 and 2.3 and 11 and 5.2 in the high and low CD4:CD8 strata, respectively.

CONCLUSIONS

In vitro resistance to ZDV developed in 64% of subjects after 180 weeks of ZDV therapy. Lower CD4:CD8 ratio at baseline was associated with faster development of resistance. In addition, the development of resistance was found to be a marker of subsequent disease progression. This association persisted after adjustment for baseline CD4:CD8 ratio. Whether in vitro resistance to ZDV is merely a surrogate marker or a determinant of disease progression remains to be established.

Bone marrow involvement in phenytoin induced 'pseudolymphoma'

We report a case of phenytoin induced lymph node enlargement with changes in both the lymph nodes and bone marrow suggestive of T-cell non-Hodgkin's lymphoma. The condition resolved after phenytoin withdrawal and the patient has no evidence of disease on bone marrow biopsy 15 months later.

Allogeneic marrow transplantation during untreated first relapse of acute myeloid leukemia

PURPOSE

The purpose of this report was to review the Seattle experience in bone marrow transplantation (BMT) for acute myeloid leukemia (AML) during untreated first relapse.

PATIENTS AND METHODS

Through 1990, 126 patients were transplanted during untreated first relapse of AML. Several preparative regimens were used, two of which involved more than 20 patients. Regimen 1 (29 patients) consisted of cyclophosphamide (CY) 120 mg/kg and 15.75 Gy of fractionated total-body irradiation (TBI) with methotrexate (MTX) given intermittently during a 102-day period to prevent graft-versus-host disease (GVHD). Regimen 2 (22 patients) consisted of the same CY and TBI treatment and a combination of MTX and cyclosporine (CSP) for GVHD prophylaxis. The remaining 75 patients were treated with 17 other transplant regimens. Outcome was compared for patients who were treated with regimen 1, regimen 2, and any other regimen.

RESULTS

The 5-year probabilities of relapse-free survival (RFS), relapse, and nonrelapse mortality for 126 patients were .23, .57, and .44, respectively. With regimen 1, relapse (.26) was significantly less than for regimen 2 (.70; P = .004) or any other regimen (.76; P = .004). Regimen 1 patients developed more acute GVHD (.67) than regimen 2 patients (.26; P = .02) or patients on other regimens (.41; P = .02), and had increased nonrelapse mortality. Nevertheless, regimen 1 patients had a significantly higher 3-year RFS (.38) than those treated with regimen 2 (.18; P = .04) or any other regimen (.20; P = .05).

CONCLUSIONS

For patients who received 120 mg/kg CY and 15.75 Gy TBI, relapse incidence was less and survival was better after GVHD prophylaxis with MTX alone than after a combination of MTX and CSP, despite a significantly higher incidence of acute GVHD. The results of treatment with regimen 1 justify future studies of the optimal timing of allogeneic BMT in the treatment of patients with AML.

Family Physicians and Exercise Counseling: Can they be influenced to provide more?

This trial took 22 volunteer family physicians and randomly exposed some to training intervention and some to no training to study the effect on frequency and quality of exercise prescription to ambulatory adults. During the 6 weeks after training, the trained physicians addressed the issue of exercise with 35.3% of patients. The untrained physicians discussed exercise with only 8.6% of their patients.

Necrotizing myositis and toxic strep syndrome in a pediatric patient

Group A beta hemolytic streptococcus (GABHS) is a common pathogen in infections of skin, soft tissue structures, and muscle. Most infections, when recognized and treated appropriately, result in a benign course. The development of more virulent forms of this organism have resulted in severe life-threatening infections. The following case of an immunocompetent host with necrotizing myositis and septic shock emphasizes the potential morbidity of GABHS infection. The spectrum of soft tissue and muscle infections is reviewed. The pathophysiology and emergency management of septic shock from GABHS is discussed.

Controlled trial of respiratory muscle training in chronic airflow limitation

BACKGROUND

Whether respiratory muscle training is of benefit to patients with chronic airflow limitation is controversial. The objective of the study was to determine the effect of resistance breathing training on physiological and functional measures in patients with chronic airflow obstruction.

METHODS

The design was a randomised, double blind, controlled trial with a six month follow up. Eighty two patients with a forced expiratory volume in one second (FEV1) of less than 70% predicted, and an FEV1/vital capacity ratio of less than 0.7, were randomised to receive training for 10 minutes five times daily with progressively larger resistances through a resistive breathing device (PFLEX) as tolerated or to a sham device which gave minimal resistance. The main outcome measures, respiratory muscle strength and endurance, a progressive exercise test, a six minute walk test and physical and emotional function (chronic respiratory questionnaire) were assessed at monthly intervals. Patients in both groups were also randomised to wear or not wear nose clips during their training.

RESULTS

No significant differences were observed between treatment and control groups, with or without nose clips, for any of the outcomes. Confidence intervals on the difference between treatments were narrow, excluding clinically important difference in any major outcome.

CONCLUSION

This training regimen fails to strengthen respiratory muscles or improve exercise or functional capacity in patients with chronic airflow limitation.

A prospective study to determine the safety of omitting the antiglobulin crossmatch from pretransfusion testing

Transfusion medicine laboratories routinely perform a series of pretransfusion serological tests including: ABO grouping, Rh typing, and investigation of the recipient's serum to detect antibodies against blood group antigens (antibody screen). As a final check, most laboratories also perform a crossmatch in which the recipient's serum is incubated with the donor's red cells followed by the addition of an antiglobulin reagent (antiglobulin crossmatch). The need for the antiglobulin crossmatch when the antibody screen is negative has been questioned because there are few antibodies that are detected by this test. Such antibodies are usually directed against low incidence antigens that are not expressed on the screening cells and in many cases the clinical importance of these antibodies is uncertain. For these reasons, we performed a prospective study in which patients requiring red cell transfusion had a group and screen performed. If the antibody screen was negative the antiglobulin crossmatch was omitted. Following the transfusion of the blood, the antiglobulin crossmatch was performed to look for any potential incompatibility. All patients were monitored both serologically and clinically. Over the 2-year interval of the study 9128 patients were entered. There were 8936 patients (97.9%) with a negative antibody screen and 26.9% (2404 patients) were transfused a total of 10,899 red cell concentrates. The antiglobulin crossmatch performed after the transfusion indicated that 168 red cell concentrates (1.5%) would have been incompatible if the antiglobulin crossmatch had been performed pretransfusion. These 168 red cell concentrates were transfused to 119 patients during 130 transfusion episodes (defined as all transfusions administered within 24 h). Of the 130 transfusion episodes, 79.2% (103/130) were false positive laboratory results. There were 27 transfusion episodes where the antiglobulin crossmatch on blood transfused was positive due to an IgG antibody. Even though these transfused red cell concentrates were designated incompatible by the antiglobulin crossmatch, none of the patients receiving this blood had clinical or serological evidence of haemolysis. We concluded that the antiglobulin phase of the crossmatch can be omitted from pretransfusion testing without putting patients at risk.