Leukocyte immunophenotyping by flow cytometry in a multisite study: standardization, quality control, and normal values in the Transfusion Safety Study. The Transfusion Safety Study Group

CD4 Count in HIV- Brain-Dead Donors: Insight into Donor Risk Assessment for HIV+ Donors

BACKGROUND

The Human Immunodeficiency Virus (HIV) Organ Policy Equity Act allows for transplantation of organs from HIV-infected individuals (HIV+), provided it is performed under a research protocol. The safety assessment of an organ for transplantation is an essential element of the donation process. The risk for HIV-associated opportunistic infections increases as circulating CD4+ lymphocytes decrease to less than 200 cells/μL; however, the numbers of circulating CD4+ cells in the HIV-negative (HIV-) brain-dead donor (BDD) is not known.

METHODS

Circulating T-lymphocyte subset profiles in conventional HIV- BDD were measured in 20 BDD in a clinical laboratory.

RESULTS

The mean age of the BDD cohort was 48.7 years, 95% were white and 45% were women. The average body mass index was 29.2 kg/m. Cerebrovascular accident (40%) was the most prevalent cause of death. Sixteen (80%) subjects had a CD4 count ≤441 cells/μL (lower limit of normal) and 11 (55%) had a CD4 count less than 200 cells/μL; 11 (55%) subjects had a CD8 count ≤125 cells/μL (lower limit of normal). CD4/CD8 ratio was below normal in 3 patients (normal, 1.4-2.6). No recipient had a recognized donor-associated adverse event.

CONCLUSIONS

Absolute numbers of CD4 and CD8 T-lymphocytes are commonly reduced after brain death in HIV- individuals. Thus, CD4 absolute numbers are an inconsistent metric for assessing organ donor risk, irrespective of HIV status.

Direct volumetric flow cytometric quantitation of CD34+ stem and progenitor cells

OBJECTIVES

In this study, we compared a classic single-platform (SP) method applying beads for enumeration of CD45+ or CD34+ cells with a new device allowing direct volumetric measurements of stem and progenitor cells.

BACKGROUND

Following apheresis and cyropreservation, the precise enumeration of CD34+ cells as key parameter of graft quality is mandatory for the clinical course after transplantation. Currently, flow cytometry with SP technique represents the 'gold standard' for such determinations.

METHODS/MATERIALS

Fresh samples, 14 from mobilised peripheral blood (PB), 9 from apheresis products (AP) and 13 samples from frozen-thawed (FT) haematopoietic progenitor cell grafts, were analysed for CD34+ cells, CD45+ cells, and in frozen-thawed samples for viability by a bead-based flow cytometric method and in parallel by a direct, volumetric flow cytometric method.

RESULTS

Comparison of CD34+ analyses revealed a significant correlation (P < 0·01) for each material between both techniques with r = 0·95 (PB), r = 0·933 (AP) and r = 0·929 (FT). Also, for analysis of CD45+ cells µL(-1) , the measured numbers evaluated with the different techniques did not significantly differ for all three materials analysed. In frozen-thawed samples, the analysis of viability was comparable for both techniques.

CONCLUSIONS

The results of this study demonstrate that a direct volumetric analysis of CD34+ cells µL(-1) or CD45+ cells µL(-1) is feasible. This technique represents a simple and economical approach for standardisation of progenitor and stem cell analyses.

Twenty years of external quality assurance in clinical cell analysis--a tribute to Jean-Luc D'Hautcourt

External quality assurance (EQA) programs in clinical cell analysis are now a consolidated item of laboratory practice. All the flow cytometric testings with an impact on clinical decision making have been submitted to regular EQA programs during the last 20 years, and this has produced internationally homogeneous guidelines, with a remarkable improvement in result reproducibility.Jean-Luc D'Hautcourt was a pioneer in this field, and his valuable contributions to flow cytometric method standardization and to the dissemination of the educational aspects of EQA programs are recognized. The different methodological approaches undertaken in the United States and Europe are discussed. The educational role of SIHON in the Benelux Countries and of UKNEQAS for Leucocyte Immunophenotyping worldwide is emphasized. Accredited and accreditating EQA programs require an impressive degree of organization and technical knowledge, so that only major international providers can afford such a task nowadays. However, small local studies still provide the necessary stimulus to the continuous improvement of the scientifical aspects of EQA schemes.

Enumeration of lymphocyte subsets using flow cytometry: Effect of storage before and after staining in a developing country setting

Lymphocyte subset estimations by flow cytometry in population-based studies require transportation of samples from the field site to the laboratory. As samples arrive late in the day they have to wait overnight before being processed. The effect of two possible approaches, sample storage for 24 h before staining and immediate staining with analysis after 24 h and 48 h were evaluated. Two sets of experiments were performed with EDTA (ethylenediamine tetra-acetate) anticoagulated peripheral blood. In the first experiment, after collection, each sample was divided into two portions. One portion was stained at the time of blood collection and the other 24 h later after keeping it at room temperature (38-45°C). In the second experiment, blood samples were stained within 1-2 h. Each sample was analyzed immediately upon completion of staining process and subsequently after 24 h and 48 h of storage at 4°C. Results suggest that blood collected in EDTA can be processed using whole blood lysis method, after storage at room temperature (38-45°C) for 24 h with some but not significant alteration in T-cell subsets. Storage at 4°C after staining for 24 h results in a lesser and insignificant loss of cells or alteration of T-cell subsets and may be the method of choice.

Reference values for peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland

OBJECTIVES

Use of domestic reference values is known to improve the accuracy of flow cytometric analysis by integrating local variation due to race, gender, and age. In the absence of previously published estimates, we now report establishment of reference values for a wide range of peripheral blood lymphocyte phenotypes applicable to the healthy adult population in Switzerland and other regions with similar demographic characteristics.

METHODS

A representative sample population was recruited from among well characterized local blood donors (n = 70) and quantitative multiparametric flow cytometry used to estimate absolute and proportional values for a range of T-, B-, and NK-cell subsets, including those associated with activation and maturity. Distribution-free methods were then applied to generate 95% reference values and to estimate the significance of gender and age-related differences.

RESULTS

Reference values were obtained for the absolute and proportional levels of total CD3(+) T cells (536-1787 cells/microL, 54.90-84.03%), helper CD4(+) T cells (309-1139 cells/microL, 32.53-62.88%), cytotoxic CD8(+) T cells (137-823 cells/microL, 11.55-38.60%), activated CD3(+) T cells expressing CD25 (7-94 cells/microL, 0.50-5.95%), CD38 (102-554 cells/microL, 5.98-26.80%), HLA-DR (18-186 cells/microL, 1.25-9.68%) or CD38/HLA-DR (4-52 cells/microL, 0.30-2.30%), activated CD4(+) T cells expressing CD25 (7-52 cells/microL, 0.33-2.80%), CD38 (69-547 cells/microL, 6.13-32.20%), HLA-DR (11-55 cells/microL, 0.80-4.43%) or CD38/HLA-DR (4-22 cells/microL, 0.30-1.35%), activated CD8(+) T cells expressing CD25 (0-12 cells/microL, 0.00-0.69%), CD38 (13-124 cells/microL, 0.93-7.03%), HLA-DR (6-108 cells/microL, 0.33-6.38%) or CD38/HLA-DR (2-47 cells/microL, 0.13-2.68%), naive CD4(+) T cells expressing CD45RA(+)/CD62L(+) (84-761 cells/microL, 9.48-41.88%), naive CD8(+) T cells expressing CD45RA(+)/CD62L(+) (42-360 cells/microL, 3.68-19.23%), memory CD4(+) T cells expressing CD45RO(+) (247-807 cells/microL, 16.50-42.15%), memory CD8(+) T cells expressing CD45RO(+) (72-377 cells/microL, 3.78-22.80%), B-cells expressing CD19 (72-460 cells/microL, 4.70-19.13%) or CD20 (66-529 cells/microL, 4.63-21.00%), total CD3(-)/(CD16(+)/CD56(+)) NK-cells (77-427 cells/microL, 5.35-30.93%), and activated NK-cells expressing CD25 (0-10 cells/microL, 0-0.50%) or HLA-DR (3-99 cells/microL, 0.20-7.28%).

CONCLUSION

It is anticipated that availability of localized reference values for an extended range of peripheral blood lymphocyte phenotypes should supplement previously published reference values and enhance the utility of flow cytometric analysis undertaken in Switzerland.

Establishment of adult peripheral blood lymphocyte subset reference range for an Asian population by single-platform flow cytometry: influence of age, sex, and race and comparison with other published studies

We established a normal reference range for peripheral blood lymphocyte subsets in a multiracial adult population by using single-platform flow cytometry. Further analysis of our cohort showed that the CD8+-cell counts decrease with age, there is a gender difference in NK cell percentages and counts, and there are significant differences in the CD3+-, CD4+-, and CD19+-cell counts between Indians and other racial groups. Overall, our results are significantly different from other published data. This difference further stresses the need for different populations to establish their own reference ranges as these may have important implications for the management of patients with human immunodeficiency virus and AIDS. The use of single-platform flow cytometry will eliminate some of the variability between different study centers, making studies more comparable. This platform should be used for future studies into the effects of age, sex, and race on lymphocyte subsets.

Reference values of lymphocyte subsets in the normal healthy adult Kuwaiti Arab population

Fluorescent monoclonal antibody labelling followed by a lysed whole blood method and flow cytometry was used to determine the lymphocyte subpopulations in 127 (64 males and 63 females) normal healthy individuals in the adult (age 18-59 years) Kuwaiti population. Relative percentages and absolute values of CD2+, CD3+, CD19+, CD4+, CD8+, HLADR+, CD56+, CD45RO+, and CD45RA+ cells were determined. The reference ranges were CD2+, 73-92% (0.95-2.99 x 10(9) per l), CD3+, 64-85% (0.83-2.71 x 10(9) per l), CD19+, 6-22% (0.05-0.61 x 10(9) per l), CD4+, 34-54% (0.45-1.65 x 10(9) per l), CD8+, 20-42% (0.29-1.17 x 10(9) per l), HLADR+, 4-23% (0.02-0.62 x 10(9) per l), CD56+, 4-22% (0.06-0.58 x 10(9) per l), CD45RO+, 16-53% (0.26-1.42 x 10(9) per l) and CD45RA+, 35-72% (0.34-2.05 x 10(9) per l). The mean CD4/CD8 ratio was 1.50+/-0.35. CD3+ cells were positively correlated to both CD4+ and CD8+ cells (P<0.001), and CD4+ cells showed a significant positive correlation with CD8+ cells (P<0.001).

Physical exercise and immune system function in cancer survivors: a comprehensive review and future directions

BACKGROUND

There are a limited number of interventions for cancer survivors following completion of primary therapy that might reduce the risk of cancer recurrence and/or secondary malignancies and increase survival times. It has been proposed that physical exercise may be beneficial by enhancing the anticancer immune system response. The purpose of the current article is to: 1) briefly describe the immune system response to tumors, 2) discuss the impact of anticancer therapy on immune system function in cancer survivors, 3) provide a systematic and comprehensive review of the extant literature examining physical exercise and immune system function in cancer survivors, and 4) offer a critical analysis of this literature and outline directions for future research.

METHODS

A comprehensive literature search up to March 2001 identified empirical articles that examined the effects of physical exercise training on immune system function in cancer survivors from CD-ROM database searches and manual searches.

RESULTS

To the authors' knowledge, six empirical studies published between 1994 and 2000 have examined physical exercise and immune system function in cancer survivors. Overall, four out of six studies reported statistically significant improvements in a number of cancer-related immune system components as a result of exercise. However, there are several limitations that must be considered when interpreting the findings of these studies. These limitations involve the samples, designs, physical exercise interventions, physical fitness assessments, and immunologic assessments.

CONCLUSIONS

Additional research is needed to determine if physical exercise in cancer survivors may reduce the risk of cancer recurrence and secondary malignancies and increase survival times.

Current status of flow cytometry in cell and molecular biology

This review summarizes recent developments in flow cytometry (FC). It gives an overview of techniques currently available, in terms of apparatus and sample handling, a guide to evaluating applications, an overview of dyes and staining methods, an introduction to internet resources, and a broad listing of classic references and reviews in various fields of interest, as well as some recent interesting articles.

SIHONSCORE: a scoring system for external quality control of leukaemia/lymphoma immunophenotyping measuring all analytical phases of laboratory performance

For the diagnosis of leukaemia and leukaemic lymphoma, clinicians frequently have to rely on the results of immunophenotyping. To improve the quality of these results, the Dutch Foundation for Immunophenotyping of Haematological Malignancies (SIHON) initiated external quality rounds in 1986. Over a period of more than 10 years, this has led to improvements in the interpretation of immunophenotyping results. However, the evaluation of results focused mainly on the correctness of the interpretation of the immunophenotypical data, leaving the preceding analytical phases unevaluated. Therefore, in 1996 SIHON developed a more comprehensive scoring system, called SIHONSCORE, covering all three phases of immunophenotyping, namely the pre-analytical (i.e. choice of the staining panels), analytical (i.e. the technical part consisting of sample preparation, data acquisition and analysis) and the post-analytical phase (i.e. the interpretation) of the laboratory process. Here, we report how SIHONSCORE was successfully applied to three consecutive external quality rounds consisting of a total of nine different cases tested. For laboratory certification, participation in external quality control programmes is required. Evidently, criteria are needed to define the minimum acceptable performance of a certified laboratory. With SIHONSCORE, a useful instrument is obtained evaluating all phases of the performance of laboratories in leukaemia and lymphoma immunophenotyping.

[Iron status, malnutrition and acute phase response in HIV-positive patients]

Nutritional status and some iron metabolism parameters of acute phase response (APR) positive and APR-negative AIDS patients were studied. Twenty-nine AIDS patients were submitted to 24h food intake recall, anthropometry, and albumin, C-reactive protein (CRP), hemoglobin, ferritin, and total iron binding capacity (TIBC) measurements. Infection plus serum CRP > 7 mg/dl were criteria for APR presence. Protein-energy malnutrition (PEM) was ascertained by body mass index (BMI) lower than 18.5 kg/m2 and height-creatinine index (HCI < 70%). PEM (77.8 vs 40%) and pulmonary tuberculosis (44. 4 vs 9.5%) were more frequent in APR-positive patients, which also had lower serum albumin (3.7 +/- 0.9 vs 4.3 +/- 0.9 g/dl), TIBC (165. 8 +/- 110.7 vs 265.9 +/- 74.6 mg/dl) and blood hemoglobin (10.5 +/- 1. 8 vs 12.6 +/- 2.3g/dl). Iron intake was similar between groups; however, serum ferritin levels (median, range) were higher among APR-positive (568, 45.3-1814 vs 246, 18.4-1577 ng/ml) patients. HIV-positive adults with systemic response to invading pathogens showed worse nutritional status than those APR-negative. In APR-positive AIDS patients, anemia appears to be unrelated to recent iron intake.

When obesity is desirable: a longitudinal study of the Miami HIV-1-infected drug abusers (MIDAS) cohort

Despite widespread nutrient deficiencies, a substantial proportion of the MIDAS cohort exhibits obesity, which has been linked to immune dysregulation in other clinical settings. Herein, the effects of obesity on immune function, disease progression, and mortality were evaluated longitudinally in 125 HIV-1-seropositive drug users, with comparison measures in 148 HIV-1-seronegative controls. Data were collected at a community clinic from 1992 to 1996, before administration of highly active antiretroviral therapy. Results indicated that overweight/obesity, defined as body mass index (BMI; kg/m2) > or =27, was evident in 18% of the HIV-1-seropositive patients and 29% of the seronegative patients. At baseline, no significant immunologic differences were observed among lean, nonobese, and obese groups. Over an 18-month period, 60.5% of the nonobese HIV-1-seropositive patients exhibited a 25% decline in CD4 cell count, compared with 18% of the obese patients (p<.004). During the follow-up period, 38% of the lean and 13% of the nonobese study subjects died of HIV-1-related causes. Measurements of BMI were inversely associated with progression to death, independent of CD4 count <200 cells/mm3 (p<.02). These data suggest that mild-to-moderate obesity in HIV-1-infected chronic drug users does not impair immune function and is associated with better HIV-1-related survival.

Flow cytometry in the exploration of the physiopathology of occupational lung disease

Flow cytometry is a simple analytical technique used for the investigation of cells taken from various sources. Cells are identified by both their physical characteristics and the presence or absence of specific molecules on the cell surface. These molecules may be either phenotypic, or induced by a specific stimulus. Flow cytometry has been used to identify the nature and extent of the immune response in several occupational respiratory conditions including occupational asthma, irritant induced respiratory problems, and asbestos related lung disease. Also, it may be of value in monitoring workplace exposure to some hazardous materials. Although of limited diagnostic value at present, the technique has provided an insight into the modulation of immune cells, and their function, in people exposed to hazardous materials in the workplace. In this review, the principals of flow cytometry will be explored and the use of flow cytometry to investigate occupational respiratory disease will be discussed.

Are there clinical and laboratory predictors of 5-year mortality in HIV-infected children and adolescents with hemophilia?

To determine factors associated with survival in a cohort of HIV-infected children and adolescents with hemophilia, an analysis of the 5-year mortality data for 207 HIV-infected young men was performed to examine the effect of selected clinical covariates on survival. The subjects were enrolled into the Hemophilia Growth and Development Study cohort from 1989 to 1990. Estimated mean time since infection at baseline was 6.7 years and mean estimated age at infection was 6.5 years. The baseline characteristics examined for their association with the hazard of death over the 5-year follow-up period were the following: absolute CD4+ cell count, hemoglobin status, skin test anergy, results of brain magnetic resonance imaging, non-hemophilia-related muscle atrophy (NHRMA), height for age, and impaired neuropsychological functioning as measured by the Vineland Adaptive Behavior and the Pediatric Behavior Scales. In all, 66 deaths occurred over the 5-year follow-up, 62 of whom met the 1987 (n = 56) or 1993 (n = 6) U.S. Centers for Disease Control and Prevention (CDC) definition of AIDS. Although each of the characteristics listed previously significantly increased the hazard of death by Cox proportional hazard regression models, only NHRMA remained a significant predictor of AIDS-related death when added to models that included each of the other cited baseline covariates.

Conservation of total T-cell counts during HIV infection: alternative hypotheses and implications

While CD4+ T-cell counts in the blood of HIV-infected individuals gradually decrease, there is a parallel increase in the number of blood CD8+ T cells such that the total number of T cells remains essentially constant for several years (1). The basis and significance of this phenomenon are not known. Based on a statistical analysis of longitudinal T-cell counts from the Transfusion Safety Study (TSS) database and on theoretical considerations, we evaluate several alternative models, including versions of the "blind homeostasis" (BH) hypothesis (1-3). At issue is the nature of the homeostatic regulation of lymphocytes and its apparent failure in HIV infection. The most plausible explanation for the conservation of total blood T-cell numbers while subset ratios change is that CD4+ and CD8+ T cells compete for a limited access to the blood compartment. Such interaction between the subsets implies, in particular, that changes in the number of CD4+ T cells occurring in other tissues cannot be reliably inferred from those observed in the blood. We reiterate propositions made earlier (4) that much of the apparent "depletion" of CD4+ lymphocytes during the asymptomatic phase of HIV infection may be attributed to redistribution between the tissues and the blood compartment.

HIV-1 infection in women is associated with severe nutritional deficiencies

Nutritional deficiencies may contribute to immune dysregulation, and have been shown to be sensitive markers of HIV-1 disease progression. Only limited information exists, however, regarding the nutritional profile of HIV-1-seropositive drug abusers. Immune and nutritional measurements were obtained in a subsample of 125 subjects from a larger cohort of drug users being followed for HIV-1 infection and cofactors of disease progression. Nutritional deficiencies, particularly vitamins A, E, and zinc, were widespread with up to 86% of the drug users exhibiting at least one nutritional alteration. Although immune parameters (CD4 count, CD8 count, beta2-microglobulin) were similar in the HIV-1-infected men and women, women had significantly poorer overall nutritional status, as measured by plasma proteins, which are considered to be sensitive markers of malnutrition. A comparison of individuals with advanced disease (CD4 count <200/mm3) revealed significantly lower levels of plasma prealbumin (p < .01), selenium, (p < .05), and greater deficiency of vitamins A (p < .01) and E (p < .05) in women than in men. The greater severity of nutritional deficiencies noted in HIV-1-infected women may be an important determinant of disease progression and survival.

Comparative rates of disease progression among persons infected with the same or different HIV-1 strains. The Transfusion Safety Study Group

Rates of HIV-1 progression vary widely. To investigate the relative effects of viral and host characteristics on course, we compared persons infected by the same and different subtype B strains. Forty-three infection chain clusters were identified, each defined by an infected blood donor, that donor's recipients, and the recipients' sexual partners, representing second and third generations of infection. Analysis of levels and rates of change in CD4 lymphocyte counts and viral load showed that members within a cluster were no more alike in their rates of change in CD4+ lymphocyte counts or viral RNA levels than among clusters. Differences in entry viral RNA levels by cluster were marginal and markedly smaller than interindividual differences. These results argue that, in general, host factors outweigh differences in viral strain in determining HIV-1 disease progression.

Posttraumatic stress symptoms, intrusive thoughts, loss, and immune function after Hurricane Andrew

OBJECTIVE

To examine the impact of and relationship between exposure to Hurricane Andrew, a severe stressor, posttraumatic stress symptoms and immune measures.

METHODS

Blood draws and questionnaires were taken from community volunteer subjects living in the damaged neighborhoods between 1 and 4 months after the Hurricane.

RESULTS

The sample exhibited high levels of posttraumatic stress symptoms by questionnaire (33% overall; 76% with at least one symptom cluster), and 44% scored in the high impact range on the Impact of Events (IES) scale. A substantial proportion of variance in posttraumatic stress symptoms could be accounted for by four hurricane experience variables (damage, loss, life threat, and injury), with perceived loss being the highest correlate. Of the five immune measures studied Natural Killer Cell Cytotoxicity (NKCC) was the only measure that was meaningfully related (negatively) to both damage and psychological variables (loss, intrusive thoughts, and posttraumatic stress disorder (PTSD). White blood cell counts (WBCs) were significantly positively related with the degree of loss and PTSD experienced. Both NKCC (lower) and WBC were significantly related to retrospective self-reported increase of somatic symptoms after the hurricane. Overall, the community sample was significantly lower in NKCC, CD4 and CD8 number, and higher in NK cell number compared to laboratory controls. Finally, evidence was found for new onset of sleep problems as a mediator of the posttraumatic symptom-NKCC relationship.

CONCLUSIONS

Several immune measures differed from controls after Hurricane Andrew. Negative (intrusive) thoughts and PTSD were related to lower NKCC. Loss was a key correlate of both posttraumatic symptoms and immune (NKCC, WBC) measures.

T-lymphocyte subsets in West African children: impact of age, sex, and season

OBJECTIVE

There has been no reference material for T-lymphocyte subsets for normal children in developing countries. We therefore used T-lymphocyte subset determinations among children in three different studies in Guinea-Bissau to construct age-related reference material and to examine possible determinants of T-lymphocyte subset levels.

METHODS

A total of 803 healthy West African children younger than 6 years were included in the three community studies of T-lymphocyte subsets among twins and singletons, after measles infection and after measles immunization. We used the immunoalkaline phosphatase method to determine T-lymphocyte subsets.

RESULTS

We found differences by age, sex, and season, whereas there were no significant differences by birth order, twinning, or ethnic group. The CD4+ percentage declined from birth to age 2 years, at which time it started to increase to higher levels at age 4 to 5 years. The CD8+ percentage increased gradually from early infancy to age 2 to 4 years. The leukocyte count peaked at age 12 to 23 months and declined thereafter, whereas the lymphocyte percentage peaked at age 1 to 5 months and declined gradually thereafter. Compared with dry-season results, the lymphocyte percentage, the absolute lymphocyte count, the absolute CD4+ T-lymphocyte count, and the CD4+/CD8+ ratio were significantly lower during the rainy season, whereas the CD8+ percentage was increased during the rainy season. Girls had higher CD4+/CD8+ ratios and lower CD8+ percentages than did boys.

CONCLUSIONS

Compared with the limited data on T-lymphocyte subsets available from healthy children in developed countries, Guinean children have markedly lower CD4+ percentages and CD4+/CD8+ ratios and higher lymphocyte percentages during the first 2 years of life, when the pressure of infections is particularly high in Africa.

Hematologic profile and lymphocyte subpopulations in hemoglobin SC disease: comparison with hemoglobin SS and black controls. The Transfusion Safety Study Group

Compared with subjects with homozygous SS disease (Hb SS), persons with hemoglobin SC (Hb SC) are known to have a more gradual loss of splenic function, a lower incidence of bacterial infections, and fewer end-organ failures. We studied hematological indices and lymphocyte subpopulations of 27 Hb SC subjects and compared them with 173 Hb SS patients and 131 black controls. Hb SC patients had higher hemoglobin levels than Hb SS subjects, lower total leukocyte, granulocyte, monocyte, and lymphocyte counts. Platelets decreased with age but not significantly, instead of increasing as among Hb SS patients. Mononuclear cells were generally similar to controls with the exception of CD8+HLA-DR+ counts resembling Hb SS. Hematologic changes in Hb SC are limited to moderate granulocytosis in children and adults, mild monocytosis in adults, and increased activation of just one lymphocyte subset among those measured.

Lymphocyte subpopulation reference ranges for monitoring human immunodeficiency virus-infected Chinese adults

Two hundred eight healthy human immunodeficiency virus (HIV) type 1- and HIV type 2-seronegative Chinese adults (78 males and 130 females; mean age, 32 years; age range, 18 to 71 years) were analyzed for lymphocyte subsets by a standardized and quality-controlled flow cytometric immunophenotyping technique. While the leukocyte differential values were comparable to those found in studies of Caucasians, the means, medians, and 95% reference ranges of lymphocyte subsets were very different. The 95% reference ranges in absolute counts per microliter of whole blood (percentage of lymphocytes) for CD3+, CD3+ CD4+, CD3+ CD8+, CD3- CD19+ (B), and CD3- with CD16+ and/or CD56+ (NK) cells were 672 to 2,368 (54.8 to 83.0%), 292 to 1,366 (23.1 to 51.0%), 240 to 1,028 (17.9 to 47.5%), 82 to 560 (5.1 to 20.8%), and 130 to 938 (7.1 to 38.0%), respectively. CD3+ CD4+ cells showed significant sex difference (for males, mean of 702 [34.8%] and standard deviation of 258 [7.5%]; for females, mean of 728 [37.3%] and standard deviation of 254 [7.4%]) as well as an increase with age of 42 (1.6%) per decade. Investigations of the NK cell population did not show similar findings. Classification of HIV disease, treatment, and prophylactic regimens based on studies which relied heavily on estimations of lymphocyte subsets alone should be used with special caution for Chinese patients. Provided that adequate quality control measures are taken to ensure comparability of data, we recommend that these ranges be used on a day-to-day basis in laboratories that have not yet established their own reference ranges.

Reference ranges and sources of variability of CD4 counts in HIV-seronegative women and men

BACKGROUND

CD4 lymphocyte counts are used to monitor immune status in HIV disease. An understanding of the variability of CD4 counts which occurs in the absence of HIV infection is essential to their interpretation. The sources and degree of such variability have not been extensively studied.

OBJECTIVES

To establish reference ranges for CD4 counts in HIV-seronegative women and heterosexual men attending a genitourinary medicine (GUM) clinic, and to identify possible differences according to gender and cigarette smoking and, in women, any effect of the menstrual cycle, oral contraceptive use and cigarette smoking.

DESIGN

Female and heterosexual male patients attending a GUM clinic and requesting an HIV-antibody test were recruited prospectively. Results from an earlier study of CD4 counts in homosexual men were available for comparison.

METHODS

Lymphocyte subpopulation analysis on whole blood by flow cytometry.

RESULTS

The absolute CD4 count and percentage of CD4 cells (CD4%) were significantly higher in women (n = 195) than heterosexual men (n = 91) [difference between the means 111 x 106/1 (95% CI 41, 180) and 3.1% (1.30, 4.88)]. The absolute CD4 count and CD4% were also significantly higher in smokers (n = 143) than non-smokers (n = 140) [difference 143 (79, 207) and 2.1% (0.43, 3.81)]. Reference ranges for absolute CD4 counts (geometric mean +/- 2SD) were calculated on log transformed data as follows; female smokers 490-1610, female non-smokers 430-1350, heterosexual male smokers 380-1600, heterosexual male non-smokers 330-1280. Among other variables examined, combined oral contraceptive pill use was associated with a trend towards a lower absolute CD4 count. Changes were seen in CD4% with the menstrual cycle. CD4 counts and CD4% did not differ significantly between heterosexual men and homosexual men (n = 45).

CONCLUSION

There is a significant gender and smoking effect on CD4 counts. The effects of oral contraceptive use and the menstrual cycle warrant further investigation.

Influence of race, age and sex on the lymphocyte subsets in peripheral blood of healthy Malaysian adults

The lymphocyte subsets in the peripheral blood of healthy Malaysian adults (212 subjects, age 18-71 years) were analysed using a flow cytometer FACScan in an effort to establish a reference range for the lymphocyte subsets. The lymphocyte subsets studied were T cells (CD3), B cells (CD19), natural killer (NK) cells (CD3- CD16+/CD56+), helper/inducer cells (CD4), cytotoxic/suppressor cells (CD8) and the helper/suppressor ratio (CD4/CD8). The distributions of T cells, CD4 cells and CD8 cells were symmetric about their means while B cells, NK cells and CD4/CD8 ratio followed a skewed distribution. Differences in race were observed for T cells, NK cells, CD4 cells and CD4/CD8 ratio where the Indians were significantly different from the Malays and the Chinese (higher T cells, CD4 cells and CD4/CD8 ratio and lower NK cells). The B cells were significantly lower in the Chinese than the Malays and the Indians. Age differences were seen only in the Chinese where increased CD4 cells and CD4/CD8 ratio, and decreased CD8 cells were observed. A sex difference was observed only in the Chinese where the CD4/CD8 ratio was significantly higher in females than males.

Instrument-dependent fluorochrome sensitivity in flow cytometric analyses

Flow cytometry has become the preferred technique by which critical clinical evaluations are made such as CD4 counts and aneuploid analyses. Mounting concern has arisen over the numerous techniques, reagents, and different flow cytometric employed to determine these data. Several studies have documented significant differences in results when different flow cytometers are utilized to analyze the same sample. Fluorochrome-dependent instrument sensitivity also has been reported by numerous investigators. As more and more procedures are performed by cytometric analysis, light scatter and fluorescence limitations, which appear to be instrument dependent, demonstrate that not all flow cytometers have the same capabilities. Attempts were made to calculate molecules of equivalent soluble fluorochrome (MESF) values on nine different flow cytometers using fluorescein isothiocyanate (FITC) and R-phycoerythrin (R-PE) labeled microsphere reference standards produced by Flow Cytometry Standards Corporation (FCSC). Dramatic differences were observed in the ability of some cytometers to resolve these microspheres. The diminished resolution appeared to be instrument model and fluorochrome dependent. We propose that diminished fluorescence resolution in certain flow cytometers could be responsible for significant variability in clinical values reported from laboratories utilizing different flow cytometers.

Interlaboratory variability of CD8 subset measurements by flow cytometry and its applications to multicenter clinical trials. NAID/NICHD Women and Infants Transmission Study Group

Recent studies have demonstrated the utility of measuring subsets of CD8+ T cells as prognostic markers in epidemiology cohort studies of human immunodeficiency virus (HIV)-infected patients. Most of these studies evaluating the value of CD8+ T-cell subsets have been performed at single centers, and few data are available on variability in the measurement of the CD8+ cell populations in multicenter trials. In the current study, we addressed this question by evaluating interlaboratory variability from the five laboratories enrolled in the Women and Infants Transmission Study sponsored by the National Institutes of Health. This study evaluated 35 HIV-positive and 28 HIV-negative proficiency testing samples sent to the laboratories for evaluation. The study focused on the robust coefficient of variation (RCV) for CD38 (11%), HLA-DR (21%), and CD57 (15%) expression on the CD8+ population. Data from the current study indicated that the variability in these measurements is greater than that for CD3+ CD4+ (RCV, 5%) and CD3+ CD8+ (RCV, 5%) cells. Knowledge of the variability of the CD8+ subset measurements should guide investigators in the design and analysis of clinical trials and epidemiology studies. Ability to obtain improved interlaboratory agreement on CD8+ subset measurements will facilitate further evaluation of these markers in HIV studies.

Uses of flow cytometry in virology

This article reviews some of the published applications of flow cytometry for in vitro and in vivo detection and enumeration of virus-infected cells. Sample preparation, fixation, and permeabilization techniques for a number of virus-cell systems are evaluated. The use of flow cytometry for multiparameter analysis of virus-cell interactions for simian virus 40, herpes simplex viruses, human cytomegalovirus, and human immunodeficiency virus and its use for determining the effect of antiviral compounds on these virus-infected cells are reviewed. This is followed by a brief description of the use of flow cytometry for the analysis of several virus-infected cell systems, including blue tongue virus, hepatitis C virus, avian reticuloendotheliosis virus, African swine fever virus, woodchuck hepatitis virus, bovine viral diarrhea virus, feline leukemia virus, Epstein-Barr virus, Autographa californica nuclear polyhedrosis virus, and Friend murine leukemia virus. Finally, the use of flow cytometry for the rapid diagnosis of human cytomegalovirus and human immunodeficiency virus in peripheral blood cells of acutely infected patients and the use of this technology to monitor patients on antiviral therapy are reviewed. Future prospects for the rapid diagnosis of in vivo viral and bacterial infections by flow cytometry are discussed.

Epidemiologic background and long-term course of disease in human immunodeficiency virus type 1-infected blood donors identified before routine laboratory screening. Transfusion Safety Study Group

BACKGROUND

The long-term course of human immunodeficiency virus type 1 (HIV-1)-related disease among seropositive blood donors has not been described. The enrollment and epidemiologic background of HIV-1-infected donors in the Transfusion Safety Study and their immunologic and clinical progression are described.

STUDY DESIGN AND METHODS

Through the testing of approximately 200,000 sera from donations made in late 1984 and early 1985, 146 anti-HIV-1-positive donors and 151 uninfected matched donors were enrolled. These two cohorts were followed with 6-month interval histories and laboratory testing.

RESULTS

Seropositive donors detected before the institution of routine anti-HIV-1 screening disproportionately were first-time donors and men with exclusively male sexual contacts. The actuarial probability of a person's developing AIDS within 7 years after donation was 40 percent; the probability of a person's dying of AIDS was 28 percent. AIDS developed more often when the donor was p24 antigen-positive at donation. Over a 3-year period, significant decreases occurred in CD4+, CD2+CD26+, CD4+CD29+, and CD20+CD21+ counts, but not in CD8+ subsets, CD20+, or CD14+.

CONCLUSION

The high proportions of first-time donations and exclusively homosexual men among seropositive donors suggest that test-seeking may have contributed to the high HIV-1 prevalence in the repository. Implementation of alternative test sites when routine donor screening began in 1985 may have averted many high-risk donations. The disease course in HIV-1-infected donors had the same wide spectrum of immunologic and clinical manifestations as were reported for other cohorts.

Age-related ranges of memory, activation, and cytotoxic markers on CD4 and CD8 cells in children

The expression of markers defining functional subpopulations on the surface of CD4 and CD8 cells changes with disease. To monitor these changes in children, it is important to establish the age-related normal changes in marker expression due to maturation of the immune system. We have studied the expression of several functionally important molecules on both CD4 and CD8 cells in 168 children (aged 0-122 months) using monoclonal antibodies and flow cytometry. Our results show that the percentage of CD4 cells decreases with age, while the CD8 percentage increases, resulting in a decrease in the CD4/CD8 ratio. The expression of CD45RO and CD29 increases with age, while CD45RA expression decreases, both on CD4 and CD8 cells. The expression of HLA-DR on both CD4 and CD8 cells, and of CD11a and CD57 on CD8 cells, is less clearly age dependent. The relationships between the marker percentages and age were not straightforward; the standard deviations and the skewness, as well as their mean values, varied as a function of age. The changes were modeled for each marker and age-specific centiles are presented.

Immune and serologic profiles of HIV-infected and noninfected hemophilic children and adolescents. Hemophilia Growth and Development Study Group

OBJECTIVES

To assess relationships among the effects of HIV on hemophilic children and adolescents' immunologic parameters and vaccine-related serology.

METHODS

We analyzed data from extensive baseline immunologic evaluations of 207 HIV antibody-positive (HIV+) and 126 HIV antibody-negative (HIV-) hemophilic children and adolescents.

RESULTS

HIV+ and HIV- participants differed significantly in T-lymphocyte subpopulation numbers, immunoglobulin levels, and seroprevalence rates for diphtheria toxoid, measles, and mumps antigens, IgG levels, IgM levels, and serologic titers to vaccine antigens showed little correlation with T-cell parameters. Proportionately more HIV+ participants were nonreactive to each and all of a panel of 7 skin test antigens (71% vs 28% anergic, RR 2.6). The odds of anergy increased 1.6 times for every decline of 200 CD4+ cells/microliters.

CONCLUSIONS

HIV had significant, largely independent T- and B-lymphocyte effects on this pediatric cohort.

Technical influences on immunophenotyping by flow cytometry. The effect of time and temperature of storage on the viability of lymphocyte subsets

The typing of lymphocyte subsets may be influenced by a variety of technical influences including the duration and temperature of sample storage and the method used for staining samples. We have extended a previous study examining the effect of storage conditions on the baseline values of a number of lymphocyte subsets. EDTA-anticoagulated samples from 13 HIV-1-positive and 15 healthy laboratory controls were analyzed for a number of lymphocyte subsets (CD3+, CD4+/CD3+, and CD8+/CD3+ T cells and CD19+ B cells) (whole blood lysis method, Becton-Dickinson FACScan flow cytometer and reagents) at 0, 24, 48, 72, and 96 h after storage at 4 degrees C, 17 degrees C or 21 degrees C. During storage at both 4 degrees C and 21 degrees C, there were significant changes in baseline values of the majority of lymphocyte subsets and some of these were related to the HIV status of the donor. The optimum temperature for storage in our system appeared to be around 17 degrees C in both our study groups. We have also used propidium iodide in order to discriminate between viable and non-viable cells during flow cytometry of lymphocytes from eight HIV-1-positive and five control subjects. The results show that for both HIV-positive and control samples stored at 4 degrees C, and for control subjects at 21 degrees C, the changes in baseline values of lymphocyte subsets observed were not due to selective loss of particular subsets arising from cell death during storage. However, there was substantial loss of cells from all three subsets in HIV-positive subjects during storage at 21 degrees C, with loss of CD8+ and CD3+ T cells being more significant than loss of CD4+ T cells.

Hypocholesterolemia is associated with immune dysfunction in early human immunodeficiency virus-1 infection

PURPOSE

Patients with the acquired immunodeficiency syndrome exhibit marked disturbances in lipid metabolism. Because altered lipid metabolism may affect immune processes, this study characterized the lipid profile of asymptomatic individuals infected with the human immunodeficiency virus (HIV-1), in relationship to immune function.

PATIENTS AND METHODS

Serum levels of triglycerides and cholesterol were determined in 94 asymptomatic HIV-1-infected (Centers for Disease Control stage II, III) homosexual men and 42 healthy seronegative control subjects. Immune assessment included measurements of lymphocyte subpopulations (CD4), immune activation (beta 2-microglobulin), natural killer cell function, and lymphocyte proliferation in response to mitogens phytohemagglutinin and pokeweed. Dietary intake was determined using a semiquantitative food frequency questionnaire.

RESULTS

Despite greater consumption of saturated fat and cholesterol, significantly lower levels of total, high-density, and low-density lipoprotein cholesterol were observed in HIV-1-seropositive men, relative to seronegative controls (p < 0.05), with 40% of the HIV-1-infected group demonstrating hypocholesterolemia (less than 150 mg/dL). Low values of total, high-density, and low-density cholesterol were associated with elevated levels of beta 2-microglobulin in HIV-1-seropositive men. No difference between the groups was noted for serum triglycerides. HIV-1-infected subjects did not demonstrate the significant inverse relationship between cholesterol and mitogen response observed in seronegative controls.

CONCLUSIONS

These findings indicate that low levels of cholesterol are prevalent during the early stages of HIV-1 infection and associated with specific alterations in immune function, suggesting that hypocholesterolemia may be a useful marker of disease progression.

Idiopathic CD4+ T-lymphocytopenia--four patients with opportunistic infections and no evidence of HIV infection

BACKGROUND AND METHODS

We describe four patients without major risk factors for human immunodeficiency virus (HIV) infection, each of whom presented with severe opportunistic infections and was found to have idiopathic CD4+ T-lymphocytopenia. We performed assays to detect the presence of retroviruses and undertook immunophenotyping of subgroups of peripheral-blood lymphocytes.

RESULTS

The opportunistic infections at presentation included Pneumocystis carinii pneumonia, cryptococcal meningitis (two patients, one with concurrent pulmonary tuberculosis), and histoplasma-induced brain abscess. During 10 to 68 months of observation, none of the four patients had evidence of infection with HIV type 1 or 2 or human T-cell lymphotropic virus type I or II on the basis of epidemiologic, serologic, or polymerase-chain-reaction studies or culture, nor was there any detectable reverse transcriptase activity. Although all the patients had severe, persistent CD4+ T-lymphocytopenia (range, 12 to 293 cells per cubic millimeter), the CD4+ cell count progressively declined in only one and was accompanied by multiple opportunistic infections. All four patients had significantly reduced numbers of circulating CD8+ T cells, natural killer cells, or B cells (or all three).

CONCLUSIONS

These four patients had idiopathic CD4+ T-lymphocytopenia with opportunistic infections but no evidence of HIV infection. Instead of the progressive, selective depletion of CD4+ T cells characteristic of HIV infection, some patients with idiopathic immunodeficiency have stable CD4+ cell counts accompanied by reductions in the levels of several other lymphocyte subgroups.

Evaluation of a dual-color flow cytometry immunophenotyping panel in a multicenter quality assurance program

A basic immunophenotyping panel that employed dual-color combinations of fluorescein isothiocyanate (FITC) and phycoerythrin (PE) conjugated monoclonal antibodies (mAb; FITC-CD45/PE-CD14, FITC-IgG1/PE-IgG2, FITC-CD3/PE-CD8, FITC-CD3/PE-CD4, FITC-CD3/PE-CD16 + PE-CD56, and PE-CD19) was utilized in a quality assurance program to determine whether the 4 laboratories participating in a multicenter AIDS study obtained similar lymphocyte subset percentage values for T cells, B cells, NK cells, and CD4+ and CD8+ T cells. Over a 1 1/2 year period, 78 shared peripheral blood specimens were prepared and analyzed in each laboratory. The CD45bright CD14- percentage for each specimen was used to correct that individual's lymphocyte subset values. Interlaboratory coefficients of variation (CV) for the human immunodeficiency virus type I (HIV) seronegative (n = 38) and HIV-seropositive (n = 40) specimens using this panel were < 3% for total T cells; < 5% for CD4+ T cells and CD8+ T cells; < or = 17% for B and NK cells; and < 8% for CD4T/CD8T ratios. The 6-tube basic immunophenotyping panel has several notable features: a) for clinical studies, it permits comprehensive evaluation of an individual's major lymphocyte subsets, i.e., T, B, NK, and CD4+ and CD8+ T cells; b) for interlaboratory proficiency testing programs, it allows the detection of differences among laboratories in measurements of several functionally distinct cell populations; and c) for within-sample quality assurance, it provides several quality control checks, including the lymphosum, i.e., the sum of an individual's corrected T+B+NK values, a sum that was generally 100 +/- 5% on the HIV-seronegative specimens analyzed in this study.

Circulating lymphocyte subsets in second- and third-trimester fetuses: comparison with newborns and adults

OBJECTIVES

Our objective was to compare the relative sizes of circulating lymphocyte subsets in fetuses, newborns, and adults.

STUDY DESIGN

Two-color flow cytometric analysis of lymphocyte cell surface markers was performed on blood from 64 fetuses, 22 newborns, and 67 normal adults.

RESULTS

All three groups had similar percentages of CD3+ total T cells, CD4+ helper T cells, CD8+ cytotoxic/suppressor T cells, and CD20+ B cells. Compared with adults, fetuses and newborns had markedly reduced percentages of CD57+ natural killer T cells and consistently increased percentages of CD5+CD20+ B cells. Most fetal and cord T and B lymphocytes expressed the activation marker CD38.

CONCLUSIONS

Similarities and age-dependent differences exist among fetal, newborn, and adult circulating lymphocyte subsets. Lymphocyte marker analysis may prove useful in the detection of fetal infection and other complications of gestation.

Immunological evaluation of late complement component-deficient individuals

The possible contribution of additional immunologic variables to the susceptibility of late complement component-deficient individuals to meningococcal disease has not been systematically examined in previous studies. Thus, we studied three groups of patients: (1) 24 healthy individuals, (2) 8 complement-sufficient individuals with a history of recurrent bacterial meningitis, and (3) 19 complement-deficient individuals with prior meningococcal infection. No statistical differences were noted among the three groups for the following parameters: the absolute number and the percentage of lymphocytes; CD3+, CD4+, CD8+, CD20+, and CD16+ cells; and the CD4+/CD8+ ratio. The concentration of C4 and circulating immune complexes was also similar among the groups. The concentrations of IgG, IgM, and IgA were slightly, but significantly, decreased in the complement-deficient individuals. Of interest, the coefficient of spontaneous and lipopolysaccharide-stimulated activation of neutrophils was significantly depressed in the deficient individuals. We hypothesize that the terminal complement components may participate in maximal neutrophil activation.

The effect of the temperature and duration of sample storage on the measurement of lymphocyte subpopulations from HIV-1-positive and control subjects

EDTA-anticoagulated blood samples from 19 HIV-1-positive subjects and 13 healthy laboratory worker controls were analysed for three lymphocyte subpopulations (CD3, CD4, CD8 T cells) (lysed whole blood method, Becton Dickinson FACScan flow cytometer) at 0, 24, 48, 72 and 96 h after venesection, having been stored at either 4 degrees C, 12 degrees C, 16 degrees C or 21 degrees C. In samples stored at 4 degrees C and 12 degrees C there was a significant fall in both %CD3 and %CD 4, and a significant rise in %CD8. At 16 degrees C the %CD8 remained stable, while there were marginal rises in %CD3 and %CD4. At 21 degrees C, the %CD8 again remained stable, while %CD3 and %CD4 rose significantly with time. These trends were independent of HIV-1 status. At each temperature studied, the rates of change of lymphocyte subpopulations were independent of each other. These results suggest that a temperature range of 14-16 degrees C may be optimal for sample storage prior to measurement of T cell subsets. They emphasise the importance of strict control on conditions if samples are to be kept for any length of time before analysis.

Quality assessment of immunological marker analysis and the immunological diagnosis in leukaemia and lymphoma: a multi-centre study. Dutch Cooperative Study Group on Immunophenotyping of Leukaemias and Lymphomas (SIHON)

In order to standardize and assess the quality of immunophenotyping of leukaemias and lymphomas for diagnostic purposes, a cooperative study group in the Netherlands, SIHON, has formulated guidelines for the composition of antibody panels to be applied and guidelines for the interpretation of the marker analysis. To assess the value of these guidelines frozen cell samples of three patients with different haematological malignancies were sent to the 26 participating laboratories twice a year. Here we present the results with respect to the marker analysis and to the immunological diagnosis on 387 samples from 18 patients. A large inter-laboratory variation was seen in the percentage of positive cells for each marker, which influenced the valuation of a marker to be discordant positive in up to 23% and discordant negative in up to 40%. No single major factor could be traced to explain the large variation in the results. However, probably due to the balanced composition of the antibody panel and to the application of the guidelines for interpretation, this variation did not much influence the agreement in immunological diagnosis. In only 13/387 samples (3.3%) differences in the percentage of positive cells caused disagreement in the final diagnosis. In 23 samples (5.9%) the disagreement was due to an incorrect application of the guidelines. Quantitative data of single observations obtained from different laboratories, in which the materials and methods are not standardized, cannot be compared; but standardization of guidelines for marker sets and for interpretation contributes to a high grade of agreement in immunological diagnosis.

Variability in serial CD4 counts and relation to progression of HIV-I infection to AIDS in haemophilic patients. Transfusion Safety Study Group

OBJECTIVE--To examine the CD4 count and its near term changes relative to progression to AIDS within 30 months and to subsequent CD4 counts. DESIGN--Longitudinal clinical and laboratory study. SETTING--Haemophilia treatment centres in six large American cities. PATIENTS--555 people with congenital clotting disorders who were infected with HIV, initially without AIDS, and seen at follow up for 6-30 months in 1986-9. MAIN OUTCOME MEASURES--Absolute CD4 counts and incidence of AIDS. RESULTS--Outset CD4 count and age were independently related to progression to AIDS (p less than 0.0001 and p less than 0.005 respectively). Patients with CD4 counts of 0.30-0.49 x 10(9) cells/l had an age adjusted risk of AIDS within 30 months of only 9% that of patients with counts less than 0.20 x 10(9)/l. Children under 10 years old had only 16% of the CD4 adjusted risk of AIDS of people aged greater than or equal to 45 years. Analysis of 149 patients' CD4 counts at the beginning and end of two successive six month intervals showed an average decrease of 11% in each six months regardless of the outset count (greater than or equal to 0.20 x 10(9)/l). For individual patients the decrease in the second six month period was unaffected by the decrease in the first six month period. CONCLUSIONS--Antiviral treatment of asymptomatic people, particularly children, with CD4 counts greater than or equal to 0.3 x 10(9)/l is questionable if predicted on near term progression to AIDS. Because of individual CD4 count variability and the low rate of progression to AIDS near term declines in individual CD4 counts are a poor index for identifying people who will rapidly progress to AIDS.

Integration of a barcode reader with a commercial flow cytometer

This report describes the application and installation of a barcode reader on a standard EPICS Elite flow cytometer. The barcode reader system eliminates keyboard entry of sample information on the cytometer. The system automates the transfer of sample information already present in our laboratory database to the cytometer at run time. The system uses a standard "off-the-shelf" bar code wand with a personal computer keyboard interface and requires no additional software at run time. No typing of sample information is required by the operator at any stage of normal sample operation at the cytometer. All operations are automatically coded into the cytometry software using the macro functions of the software. Tubes are inserted into the tube reader and sample information is transferred automatically into the cytometer. We have found that the system allows rapid and continuous operation of routine clinical and research samples. This automated data entry also reduces the possibility of data input errors.

In the mouse the maturation stage of the peripheral CD4+ CD45RA+ subset is different from that of the CD8+ CD45RA+ subset

In vitro studies have suggested that the presence of CD45RA on subsets of CD4 and CD8 cells defines naive T cells and that, in response to antigen, CD45RA+ cells become CD45RA- along a differentiation pathway. To test the hypothesis that CD45RA+ cells are naive cells which have just left the thymus, young mice were thymectomized. This would be predicted to lead to a fall in the size of the peripheral pool of CD45RA+ T cells. However, the changes in the size of this pool would also be dependent on the life-span and self renewal capacity of the CD45RA+ T cells in the periphery. Therefore, to test the contribution of the thymus to the peripheral CD45RA+ pool, the percentage of CD45RA+ cells among spleen lymphocyte subsets was studied from 10 days up to 2 years of age in thymectomized and control mice. We also studied the expression of the memory marker CD44 on the CD45RA subsets of CD4 and CD8 cells, as well as the effect of in vitro activation on expression of CD45RA. Our results show that CD8+ CD45RA+ cells are mainly CD44- and their maintenance is dependent on the presence of the thymus. In contrast, the majority of CD4+ CD45RA+ are CD44+ and are not affected by thymectomy. This indicates that the maturation stage of CD8+ CD45RA+ cells is different from that of CD4+ CD45RA+ cells.

Lymphocyte subset reference ranges in adult Caucasians

We report here the distributions of lymphocyte populations bearing the following antigens: CD3 (T cells), CD19 (B cells), CD4 (T helper/inducer cells), CD8 (T suppressor/cytotoxic and some NK cells), and CD3-, CD16+, and/or CD56+ (NK cells). At four sites, analyses were performed on healthy, normal subjects between the ages of 18 and 70, using identical flow cytometry systems and techniques. Reference ranges (unadjusted for sex differences and age variation) are CD3 (61 to 85%), CD19 (7 to 23%), NK (6 to 29%), CD4 (28 to 58%), and CD8 (19 to 48%). The lymphocyte subpopulation distributions for all antigens were found to be similar at all sites. By combining data from all sites, it has been possible to estimate age variation and sex differences for each of these subpopulations. Age and sex associated differences are substantial for some lymphocyte subsets (CD3, CD4, NK cells), and proper accounting of these effects is essential in evaluating the individual patient, if further disease-related variation is to be accurately and consistently assessed. It appears possible to recommend reference ranges for lymphocyte population parameters applicable across national and laboratory boundaries. These ranges provide a basis for comparing results from different institutions and for combining such results on subjects and patients from several institutions, provided the methodology and equipment are identical at all sites.

Immunologic function in a cohort of human immunodeficiency virus type 1-seropositive and -negative healthy homosexual men

The study objectives were to determine the early effects of human immunodeficiency virus type 1 (HIV-1) infection on both phenotypic and functional immunologic markers in healthy homosexual men, to ascertain the relationships of these markers to each other, and to discover which markers were affected by enrollment in an AIDS study in which HIV-1 serostatus would be determined. The major findings were as follows. (i) The CD4/CD8 ratio and lymphocyte proliferative response to pokeweed mitogen were the characteristics most affected by early HIV-1 infection. (ii) The loss in CD4 cells observed in the HIV-1-positive homosexual men was entirely due to diminished numbers of the memory subset. CD4+ CD29+. The reciprocal subset of CD4, CD4+ CD45RA+, did not differ in the two groups of homosexual men at either time point or in the controls. (iii) Prior to learning their HIV-1 serostatus, HIV-1 antibody-negative risk-group males had lower phytohemagglutinin (PHA) responses than the controls did. In the assays following notification of their seronegativity, however, these men had PHA values which were not different from those of the controls. In the HIV-1-positive group, the responses to both PHA and pokeweed mitogen were below those of both HIV-1-negative groups and did not change after serostatus notification. (iv) The activity of natural killer cells was lower in the risk-group men than in the controls at both pre- and postdiagnosis but was not related to HIV-1 serostatus. (v) In this cohort of homosexual men, the CD4/CD8 ratio correlated significantly with the functional measures of immunologic status in the HIV-1-positive men, but not in the HIV-1-negative men.

Flow cytometry and cell-separation procedures

A series of small incremental advances characterize the year's technical developments in flow cytometry, and these now extend the use of the technique to even the molecular level. The increasing application of immunomagnetic-bead separation procedures dominates the developments in other cell-separation procedures.

Generalization of normal discriminant analysis using Fourier series density estimators. Transfusion Safety Study Group

In this paper we examine the efficiency of a generalization of the traditional normal linear (LDA) or quadratic (QDA) discriminant analysis. This procedure (the generalized discriminant analysis, GDA) replaces each normal density used in the traditional classification rule by a Fourier series density estimator which 'adjusts' the normal density if the data deviate markedly from normality (for example, heavily skewed or multimodal). We derive the GDA in both the univariate and multivariate situations. In a simulation study for the univariate situation, we evaluate the relative efficiency of the GDA. In addition, we demonstrate the performance of the GDA through a series of multivariate applications. We conclude that if the distributions of the data do not deviate markedly from normality, the GDA is as efficient as the LDA or QDA. On the other hand, if either of the distributions deviates from normality, then the GDA, which performs as a semiparametric discriminant procedure, is more efficient than the LDA or QDA.