Storage of platelets in additive solutions: a multicentre study of the in vitro effects of potassium and magnesium

BACKGROUND AND OBJECTIVES

In a preliminary study, the presence of potassium and magnesium in a modified synthetic medium (PAS-III) was found to have a significant influence on platelet metabolism (using apheresis-derived, as well as buffy-coat-derived platelets) when compared with standard PAS-III. The differences included reduced glycolysis, as evidenced by lower consumption of glucose and lower production of lactate, but also better preservation of pH and hypotonic shock response reactivity. The results suggested that storage in modified PAS-III containing 20% plasma was comparable to storage in standard PAS-III containing 30% plasma. To confirm the preliminary results and to evaluate the effects of different preparation protocols, an international multicentre study, which included 11 different sites, was conducted.

MATERIALS AND METHODS

Platelets from 30 pools of approximately 20 buffy coat (BC) units each and 24 pooled apheresis platelet units were aliquoted for storage in plasma (reference) or synthetic medium using either a specific additive solution (PAS-III) containing 30% plasma or a modification of PAS-III containing 5.0 mm potassium and 1.5 mm magnesium (PAS-IIIM) and either 30% or 20% plasma. Units were stored at room temperature with agitation for 7 days during which in vitro testing was carried out for biochemical, haematological and functional parameters.

RESULTS

Storage of platelets in PAS-IIIM resulted in a reduction in the rate of glycolysis and better retention of pH and hypotonic shock response reactivity. Storage in PAS-IIIM containing 20% plasma appeared to result in the retention of in vitro properties, similar to those observed during storage in standard PAS-III containing 30% plasma.

CONCLUSIONS

The results of this study confirm the preliminary results. Similar results were seen with platelets prepared by BC and apheresis methods, despite differences in equipment, the preparation technique and in the final platelet contents achieved in the platelet units. Storage of platelets in PAS-IIIM should be considered to improve platelet function and allow plasma reduction to 20%.

The 'cherry buffy-coat syndrome', a cause of decreased platelet yield in platelet concentrates obtained from buffy-coats

BACKGROUND AND OBJECTIVES

A large number of European blood centres, including our own, use the buffy-coat method for platelet production. In this article we describe a previously unnoticed phenomenon shown by a proportion of buffy-coats, which display an unusually bright cherry colour and low platelet counts.

MATERIALS AND METHODS

We performed bacterial cultures, platelet counts, pO2, pCO2 and pH, and evaluated platelet activation by flow cytometry in cherry versus normal-colour (control) buffy-coats. In addition, we compared donor characteristics in the two groups and platelet counts in the packed red blood cells (RBC) obtained from the original donations. Finally, we monitored the frequency of cherry buffy-coats in the bags of three manufacturers, and determined the concordance rate of two trained technicians in detecting cherry buffy-coats.

RESULTS

Bacterial cultures were negative. Cherry buffy-coats contained significantly fewer platelets, more O2, less CO2 and had a significantly higher pH than normal buffy coats. Platelet activation was slightly higher in cherry buffy-coats. RBC from donations yielding cherry buffy-coats contained a significantly higher number of platelets than controls. Donor characteristics were not significantly different. Cherry buffy-coats were significantly more frequent with bags from one manufacturer (24%) than from others (9% and 11.6%). The concordance study showed excellent agreement.

CONCLUSIONS

Our hypothesis is that the cherry colour is caused by O2 accumulation in buffy-coats with low platelet counts. The latter may be caused by platelet activation and aggregation during blood processing. Further work is needed to determine the cause of this phenomenon, its frequency in different laboratories and means to prevent it.

Cancer risk among men with, or at risk of, HIV infection in southern Europe

OBJECTIVE

To evaluate the cancer risk in southern European men with, or at risk of, HIV infection.

DESIGN

An analysis of longitudinal data to assess time-dependent rare events.

METHODS

Data from a cohort of HIV seroconverters, and from two hospital-based HIV seroprevalent cohorts were combined and analysed. The number of cancer cases observed was compared with the expected number, obtained from cancer incidence rates among men in the general population. Age-standardized incidence ratios (SIR) and their 95% confidence intervals (CI) were computed.

RESULTS

A total of 19,609 person-years of observation were accumulated among HIV-positive men, and 7957 person-years among HIV-negative men. Among HIV-positive men, statistically significant increased SIR were seen for Hodgkin's disease (HD) (SIR = 8.7), liver cancer (SIR = 11.0), and cancer of the salivary glands (SIR = 33.6). An excess of lung cancer was seen among intravenous drug users (IDU), but not among homosexual men. When the risk of all non-AIDS-defining cancers was considered, HIV-positive men had a nearly twofold excess (95% CI: 1.2-2.8). A risk of similar magnitude emerged among HIV-negative IDU (95% CI: 1.0-4.5), largely attributable to lung cancer and HD.

CONCLUSION

These findings confirm that HIV infection increases the risk of HD, whereas they suggest that the risk of hepatocellular carcinoma may also be enhanced by HIV infection. The observation of an elevated risk of lung cancer in both HIV-positive and HIV-negative IDU points to personal behaviours unrelated to HIV infection.

Phenotypic characteristics and tendency to apoptosis of peripheral blood mononuclear cells from HIV+ long term non progressors

The aim of this study was to analyze (i) phenotype, (ii) in vitro spontaneous and induced apoptosis, (iii) glutathione (GSH) intracellular content and (iv) inhibitors of apoptosis of potential therapeutical use in peripheral blood mononuclear cells (PBMC) from HIV+ long term non progressors (LTNP), in comparison with progressors (HIV+P) and seronegative controls (HIV-). Three groups of subjects were studied: 15 HIV+P (patients losing >150 CD4+/year), 9 LTNP (subjects infected by HIV for at least 7 years without clinical and immunological signs of progression, with a mean of 898 CD4+/microL) and 18 HIV-. All subjects were living in a large community for former drug addicts, and were matched for age and sex. We used flow cytometry for analyzing PBMC phenotype and apoptosis; high performance liquid chromatography for measuring intracellular GSH content. PBMC phenotype of LTNP shared characteristics with those of both HIV- and HIV+P. Indeed, LTNP showed a normal number CD4+ cells (an inclusion criteria), but significantly increased numbers of CD8+ lymphocytes, activated T cells, CD19+, CD5+ B lymphocytes and CD57+ cells, as well as a decrease in CD19+, CD5- B lymphocytes and CD16+ cells. In LTNP, spontaneous apoptosis was similar to that of HIV- and significantly lower than that of HIV+P. Adding interleukin-2 (IL-2) or nicotinamide (NAM) significantly decreased spontaneous apoptosis in LTNP and HIV+P. Pokeweed mitogen-induced apoptosis was also similar in LTNP and HIV-, but significantly lower than that of HIV+P. In HIV+P, but also in LTNP, spontaneous apoptosis was inversely correlated to the absolute number and percentage of CD4+ cells and directly correlated to the number and percentage of activated T cells present in peripheral blood. GSH intracellular content was greatly decreased in PBMC from HIV+P and slightly, but significantly, reduced in LTNP. Adding 2-deoxy-D-ribose, an agent provoking apoptosis through GSH depletion, to quiescent PBMC resulted in similar levels of massive cell death in the three groups. This phenomenon was equally prevented in the three groups by N-acetyl-cysteine but not by IL-2. A complex immunological situation seems to occur in LTNP. Indeed, PBMC from LTNP are characterized by a normal in vitro tendency to undergo apoptosis despite the presence of a strong activation of their immune system, unexpectedly similar to that of HIV+P. Our data suggest that NAM and IL-2 are possible candidates for reducing spontaneous apoptosis in HIV infection.

Acetyl-L-carnitine administration increases insulin-like growth factor 1 levels in asymptomatic HIV-1-infected subjects: correlation with its suppressive effect on lymphocyte apoptosis and ceramide generation

The aim of this study was to investigate the impact of long-term acetyl-L-carnitine administration on CD4 and CD8 absolute counts, apoptosis, and insulin-like growth factor-1 (IGF-1) serum levels in HIV-1-infected subjects. The generation of cell-associated ceramide and HIV-1 viremia were also investigated. Eleven asymptomatic, HIV-1-infected subjects were treated daily with acetyl-L-carnitine (3 g) for 5 months. Immunologic and virologic measures and safety were monitored at the start of the treatment and then on days 90 and 150. Altogether our findings suggest that acetyl-L-carnitine administration has a substantial impact on the main immunologic abnormality associated with HIV infection, the loss of CD4 cells, by reducing the rate of apoptotic lymphocyte death. The reduction of ceramide generation and the increase of the serum levels of IGF-1, a major survival factor able to protect cells from apoptosis by different stimuli and conditions, could represent two important mechanisms underlying the observed anti-apoptotic effects of acetyl-L-carnitine.

Clinical cryptosporidiosis and human immunodeficiency virus (HIV)-induced immunosuppression: findings from a longitudinal study of HIV-positive and HIV-negative former injection drug users

The natural history of cryptosporidiosis was investigated during a waterborne outbreak among 1731 members of a drug rehabilitation community in Italy; 19.6% of the members were positive for human immunodeficiency virus (HIV). Demographic and clinical information and pre-outbreak serum samples were available. Clinical data were analyzed, stratifying the study population by HIV serostatus and CD4 cell count. The attack rate of clinical cryptosporidiosis was 13.6% among HIV-negative individuals and 30.7% among HIV-positive individuals, although in the latter, it varied according to CD4 cell count. Clinical symptoms and their duration were also related to CD4 cell count. Chronic symptoms were observed in only 16 individuals (15.4%), who all had <150 CD4 cells at the onset of the illness. Among a systematic sample of 198 individuals, 14.1% already had anti-Cryptosporidium antibodies before the outbreak, and 51.2% developed specific antibodies during the outbreak. The development and clinical manifestations of cryptosporidiosis were strongly influenced by the level of HIV-induced immunosuppression.

A micro colorimetric assay using cryopreserved monocytes to evaluate antibody-mediated red cell-monocyte interaction

BACKGROUND AND OBJECTIVE

A number of in vitro assays based on the interaction of red cells with monocytes have been used to determine the clinical significance of red cell antibodies. When used in our laboratory, one of these assays (the monocyte-macrophage phagocytosis assay-MMPA), was very time consuming and showed great variability.

METHODS

We set up a monocyte phagocytosis colorimetric assay (MPCA), using standard microtiter plate wells coated at 37 degrees C for 1 hour with monocytes from healthy donors. After washing the wells to remove non-adherent monocytes, test red cells are added to the wells. Sensitized red cells bind to the monocytes, which are lysed after incubation to measure red cell phagocytosis. This is done by hemoglobin detection in the lysate through reaction with o-phenylenediamine and absorbance evaluation with a colorimeter. The results are expressed as the phagocytosis index (PI), which is calculated with the following formula: PI = [1-(A450 unsensitized red cells/A450 sensitized red cells)] x 100. In this study we determined: the source of MPCA variability; the precision of MPCA results; the correlation between MMPA and MPCA results; the MPCA reference values and the MPCA and MMPA execution times.

RESULTS

MPCA variability depended largely on the monocyte source. The smallest variation coefficient of the results of replicate assays (19-21%) was found using pooled, cryopreserved monocytes. When performed with a pool of cryopreserved monocytes from 10 subjects, the SD of PI values obtained in replicate assays showed little variation (11-13) over the range of anti-D concentrations tested (from 18.75 to 300 ng/mL). A linear correlation coefficient r of 0.96 was obtained when MPCA and MMPA were performed in parallel, and the 95th centile of PI reference values determined with red cells of 40 non-transfused surgical patients free of irregular red cell antibodies was 7. MPCA execution time was 56% of that needed to perform MMPA.

INTERPRETATION AND CONCLUSIONS

These studies show that MPCA is an easy and reproducible assay which allows objective and automated evaluation of red cell phagocytosis.

Community-acquired pneumonia in a cohort of former injection drug users with and without human immunodeficiency virus infection: incidence, etiologies, and clinical aspects

Although the association among bacterial pneumonia, human immunodeficiency virus (HIV) infection, and injection-drug use seems to have been well established, accurate estimates of the risk of community-acquired pneumonia among HIV-positive and HIV-negative injection-drug users (IDUs) are still needed. To estimate the incidence of pneumonia in a community of former IDUs, we followed 4,236 persons between 1991 and 1994; 1,114 (26.3%) were HIV-positive and 3,122 (73.7%) were HIV-negative. All patients were evaluated for pneumonia by standard criteria, a serum sample was obtained from each participant at least once a year, and laboratory values were monitored. Overall, 149 episodes of pneumonia occurred among HIV-positive patients and 61 among HIV-negative patients; incidence rates were 90.5 and 14.2 (per 1,000 person-years), respectively. The most common etiologic agents were Streptococcus pneumoniae, Chlamydia pneumoniae, and Haemophilus influenzae. Among the HIV-positive former IDUs, there was a 1.37-fold increase in the relative risk of pneumonia for every decrease of 100/mm3 in the CD4 cell count (95% confidence interval, 1.16-1.61). The incidence of community-acquired pneumonia was markedly higher among HIV-positive participants than among HIV-negative ones, a finding similar to that concerning the general population.

Outbreak of Chlamydia pneumoniae infection in former injection-drug users

In a retrospective analysis of lower respiratory tract infections in an ex-injection-drug users community, we found an outbreak (April to July 1991) of Chlamydia pneumoniae infection. The epidemic occurred in a group of 26 community members (23 men and 3 women, mean age, 28.9--3 years) living and working together, who underwent acute and convalescent serologic tests for Mycoplasma pneumoniae, Legionella pneumophila, cytomegalovirus, adenovirus, Coxiella burnetii, and Chlamydia pneumoniae. All subjects were submitted to chest radiograph, while sputum and blood cultures were performed in symptomatic patients. Antibodies to C pneumoniae were determined by a microimmunofluorescence test. Among all subjects studied (13 HIV-1 positive and 13 HIV-1 negative), 11 (8 HIV-positive and 3 HIV-negative) developed pneumonia, 2 (1 HIV-positive and 1 HIV-negative) developed pharyngitis, and 2 (1 HIV- positive and 1 HIV-negative) developed flu-like syndromes sustained by C pneumoniae; in 4 subjects (2 HIV-positive and 2 HIV-negative) suffering from flu-like syndrome, no causal agents were found. Seven subjects (one HIV-positive and six HIV- negative) remained asymptomatic without any evidence of infection. The prevalence of antibodies to C pneumoniae in HIV-1-positive subjects observed in a sample of community members was significantly higher than in HIV-1-negative subjects. C pneumoniae seems to be involved in respiratory tract infections in HIV-1-infected subjects. Our data suggest that C pneumoniae should be included in the diagnostic approach of respiratory infections in HIV-infected subjects.

White cell-reduced red cells prepared by filtration: a critical evaluation of current filters and methods for counting residual white cells

White cell (WBC) reduction, red cell (RBC) recovery, and filtration time were determined in 1-day-old standard and buffy coat-depleted RBCs filtered in the laboratory through six commercial filters for WBC reduction. Residual WBCs were counted with a Bürker chamber (BC), with a Nageotte chamber (NC), and by flow cytometry (FC). Results show that BC counts were 0 in several cases in which WBCs were detected with NC and FC, which indicated that the traditional BC method is too insensitive in use with currently available filters. Calibration curves performed by FC and with NC with samples containing known concentrations of WBCs from 1000 to 1 per microL showed that both FC and NC detected, on average, 67 percent of WBCs present in the samples (efficiency). However, the efficiency of FC showed small variability (61-70%) at different WBC levels, whereas the variability with NC was large (39-91%). This greater variability prevented the correction of NC counts by using a single factor and indicated difficulty in NC standardization. Therefore, because our main aim was to compare different filters rather than to define absolute levels of WBC contamination, uncorrected FC and NC counts were chosen to be reported. True WBC counts per unit should not exceed values that can be obtained by dividing uncorrected counts by the lowest efficiencies (61% for FC and 39% for NC). Uncorrected NC and FC counts were below 2 x 10(6) per unit in all units processed through three of the filters and below 5 x 10(6) per unit in all units processed through the other three.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet concentrates from buffy coats: improved conditions for preparation and evaluation in routine clinical use

Since 1990, platelet concentrates prepared by soft centrifugation of buffy-coat pools diluted with a glucose-free, commercially available crystalloid solution (BC-PC) are the first choice product for all platelet recipients in our institution. Numerous in vitro and in vivo observations from our own and other laboratories indicate that BC-PC compare favorably to PC prepared from platelet-rich plasma (PRP). In the present in vitro study we evaluated traditional and bottom-and-top bags and modified centrifugation conditions with the aim of increasing in vitro platelet yield in BC-PC. This was 14-18% higher compared with our previous protocol when prolonged centrifugation and bottom-and-top bags were used. In addition, we evaluated post-transfusion platelet count increments in 42 unselected adult hematological patients routinely transfused with 703 1-5 day-old BC-PC pools. Transfusion data were managed with PLATELET, an MS-DOS compatible program which includes automated calculation of transfusion efficacy and periodic patient reports. Mean pre-, 1 h and 24 h post-transfusion platelet counts were 16, 38 and 28x10 9/L, respectively. Mean 1 h and 24 h post-transfusion platelet count increments, expressed as percentage of expected, were 40 and 24%, respectively. These data were similar to those obtained previously in 189 unselected hematological patients given 2432 PRP-PC transfusions (mean 1 h post-transfusion increment 46% of expected). The present in vitro study confirms that similar platelet yields can be obtained with the BC and PRP methods. In vivo findings show that also in routine conditions post-transfusion increments of PRP-PC and BC-PC are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Modifications of abdominal fat and hepatic insulin clearance during severe caloric restriction

Using computed tomography on 19 obese female subjects, we determined abdominal adipose tissue, both subcutaneous and visceral adipose tissue, before and after 2 weeks of a very low caloric diet (VLCD). The following parameters were also determined before and after 15-20 days of VLCD: plasma glucose and insulin levels, oral glucose tolerance test, basal pancreatic insulin secretion estimated by fasting C peptide (Cp), and fasting insulin hepatic clearance calculated by Cp/insulin molar ratio. After VLCD the body weight and body mass index significantly declined (p less than 0.01); whereas abdominal adipose tissue and visceral abdominal tissue (VAT) significantly decreased (p less than 0.01), modifications of subcutaneous abdominal tissue (SAT) were not significant. Fasting insulin levels and plasma glucose response to oral glucose load significantly decreased (p less than 0.05). Insulin response remained unchanged. Cp immunoreactive insulin (IRI) significantly increased (p less than 0.01). A significant positive correlation was found between delta VAT and delta Cp/IRI before and after VLCD (p less than 0.01). Our data seem to suggest that the weight loss induced by VLCD fundamentally involves a decrease in VAT. The reduction in visceral fat could be associated with an increase in hepatic insulin clearance.