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Percentages and absolute counts of CD4+ lymphocytes, as determined by T-lymphocyte immunophenotyping (TLI), are prognostic, as well as diagnostic, of the course of human immunodeficiency virus type 1 infections and are important indicators for initiating Pneumocystis carinii pneumonia prophylaxis and antiretroviral therapy. In December 1990, we requested that a nonrandom sample of 17 laboratories provide us with typical reports of their TLI results from an immunodeficient patient and from a patient whose TLI results were within the laboratory's normal reference ranges. We also searched published literature and documents proposed by professional organizations for recommendations regarding T-lymphocyte testing and reporting. This article compares guidelines for reporting TLI results, as proposed by the National Committee for Clinical Laboratory Standards in Document H42-P, with samples of reports obtained in our case series. Most reports follow some, but not all, of the proposed guidelines. A majority of the laboratories provided interpretations of the results in their reports. We found considerable variation in normal reference ranges. We describe this variation in detail for the CD4+ T-lymphocyte counts and CD4+ T-lymphocyte percentages. This article describes some of the TLI result report forms currently being used and identifies important quality issues in this rapidly expanding area of clinical laboratory testing.

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PATIENTS AND METHODS: A randomised study was performed to compare the frequency of postdural puncture headache in 56 patients who underwent spinal anaesthesia for extra-corporeal shockwave lithotripsy using either a Sprotte 24 G (n = 28) or Vygon 29 G or Quincke type needle (n = 28). Frequency of headache was recorded in a similar group of 28 patients who received general anaesthesia. RESULTS: Dural puncture was easier with the Sprotte 24 G cannula than with the less stable Quincke needle, as documented by a significantly shortened time for insertion of the cannula (4.6 +/- 2.6 vs 8.6 +/- 6.3 min, P less than 0.005). The total frequency of post-operative headache was 57% in the Vygon 29 G group and 25% in the Sprotte 24 G group; 21% of patients in the general anaesthesia group complained of headache. Frequency of postdural puncture headache, classified as being posture-related, was 25% in the 29 G Vygon group, compared with 11% in the 24 G Sprotte group (P = 0.148). When only moderate and severe postdural puncture headache was considered, there was a significant difference (25% vs. 4%; P = 0.026) in favour of the Sprotte cannula. DISCUSSION AND CONCLUSIONS: Thus, the 24 G Sprotte needle was at least as effective as the 29 G Vygon needle, and there is a suggestion that the former is more effective in minimising the incidence of moderate or severe postdural puncture headache.

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In 1986, a performance evaluation program at the Centers for Disease Control was implemented to assess the quality of performance of laboratories testing for human immunodeficiency virus type 1 antibody and to identify problems that occur during the testing process. Laboratories participating in the Centers for Disease Control Model Performance Evaluation Program for human immunodeficiency virus type 1 antibody testing furnished enzyme immunoassay results after they tested performance evaluation panels that were sent to them in August and November 1989. The panels consisted of 10 individual samples containing antibody-negative and antibody-positive samples, some of which were duplicates. Not all laboratories received the same panel of samples. Low false-negative and false-positive rates, as well as high intrashipment and intershipment reproducibility, indicate that most laboratories did not experience difficulty in testing performance evaluation samples sent to them in August and November 1989.

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In three performance evaluation surveys, panels that consisted of human T-lymphotropic virus type I or type II (HTLV-I/II) antibody-positive and -negative plasma samples were mailed to laboratories that voluntarily participated in the Centers for Disease Control Model Performance Evaluation Program. Donor samples were identical among surveys. In each survey, more than 98% of the laboratories reported enzyme immunoassay (EIA) test results; about 11% also reported results of Western blot (WB) testing. Variation in analytic sensitivity (96.7% to 99.4%) and specificity (98.3% to 99.5%) of EIA tests was noted in the three surveys. For WB testing, no nonreactive interpretations were reported for HTLV-I/II antibody-positive samples in any survey; however, indeterminate interpretations were reported for 35.2% to 40.7% of the WB tests that were performed on HTLV-I/II antibody-positive samples. More than 95% of these indeterminate WB test interpretations were reported for HTLV-II antibody-positive samples. Although HTLV-I/II antibody tests are generally sensitive and specific, their accuracy could be further improved by increasing the specificity of EIA tests and the sensitivity of WB tests.

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We surveyed laboratories to assess their capacity to perform T-lymphocyte immunophenotyping. Of the 1026 respondents, 279 located in 41 states and the District of Columbia performed this type of testing. Most laboratories were located in hospitals, reported a low weekly test volume, and indicated that it took 6-24 weeks for flow cytometer operators to become proficient. Many laboratories appear to have the capacity to perform additional CD4+ cell testing, but training additional operators may be necessary. The paucity of laboratories performing T-lymphocyte immunophenotyping in the public sector may affect referral patterns from that setting.

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To determine the precision of cellular fluorescence intensity (FI) measurements derived from labeled microbead standards, FI results were compared from 43 different flow cytometers in 34 laboratories. All laboratories analyzed prepared aliquots of fluoresceinated calf thymocyte nuclei (Fluorotrol), human lymphocytes stained with fluoresceinated anti-CD4 antibody, and fluoresceinated microbeads used as both internal and external standards. Measurements were conducted by most laboratories on the third and fourth days after sample preparation. Results for percent of events within the gates and the histograms returned by participants indicated that the samples had remained stable and that gated populations had been properly identified. All standard curves showed strong linearity, and the pooled results from all standards produced a best-fit curve that was in close agreement with the assigned values. Nonetheless, results for cellular FI were highly variable, with CVs of 20-34%. Agreement within lab/instrument was much better, with CVs ranging from 3.0 to 9.9%. The overall variability was not obviously attributable to differences in the types of cytometer, nor could it be explained by attributes of the standard curves or any other single variable examined. However, the application of a corrective factor based on FI results for Fluorotrol allowed a two-fold improvement in the precision of FI measurements on CD4-stained lymphocytes, with an overall CV of 11%. Uncharacterized differences in the operating conditions of flow cytometers can influence cellular FI measurements, but consistent results can be obtained if a stained cellular calibrator is analyzed in addition to the proper microbead standards.

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Fluorescence intensity calibration was evaluated in a model system for flow cytometers using commercially available fluorescein-labeled microbeads as internal standards and stabilized fluoresceinated thymus cell nuclei (Fluorotrol) as surrogates for stained mononuclear cells. Spectrophotometrically determined calibration values for the microbeads were used to generate a standard curve that converted green fluorescence histogram channels into molecular equivalents of soluble fluorescein (MESF). In 19 analyses repeated during a single run, the coefficients of variation (CVs) for the derived MESF values on both dimly and brightly stained Fluorotrol populations were less than 2%. In 26 separate determinations over 14 weeks, the CVs of the derived MESF values were less than 3%. The MESF values of the dim and bright Fluorotrol populations derived from the microbead standard curves were both about 50% lower than those determined by direct spectrophotometric analysis of Fluorotrol. The analytical imprecision of fluorescence intensity measurements in this idealized model system has a CV less than 3%, and the analytical inaccuracy shows that calibration in MESF units remains uncertain over about a two-fold range.

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A female tetraplegic patient developed a pressure sore of the chest wall leading to an empyema of the lung and respiratory failure. The pressure sore resulted from the commonly practised habit of grasping the upright of the wheel chair with the upper arm in order to gain stability.

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Skin electrical resistance is determined by the degree of sweating of the skin which is, in turn, related to sympathetic nervous system activity in the area concerned. It is increased when the nerves supplying the area are damaged or blocked by local anaesthetic agents. We have assessed the temporal and spatial relationship between the onset of sympathetic and sensory loss in the hand following brachial plexus block in 44 patients. Skin electrical resistance, measured using a simple ohm meter, has been shown to increase within 2 min of brachial plexus blockade with 1% lignocaine and adrenaline 1:200,000. This increase is an early and reliable indicator of subsequent, and occasionally delayed, sensory loss.

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Changes in finger blood flow, arm blood flow and cardiac output were measured using electrical impedance plethysmography in 20 patients after brachial plexus anaesthesia. The anaesthetic solution used in all patients was 1% lignocaine with adrenaline 1:200,000. Significant increases in cardiac output and blood flow to the unanaesthetised arm were observed immediately after anaesthesia had become effective. A highly significant increase in the blood flow to fingers of the blocked hand was observed throughout the period of anaesthesia but there was no overall increase in the blood flow to the arm. It is suggested that the adrenaline contained in the local anaesthetic solution increased the cardiac output and caused arterial vasoconstriction at the site of injection.

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The use of intravenous administration systems incorporating 3-mm internal diameter tubing is becoming more common in hospital practice. The maximum flow-rate of crystalloid solutions through 3-mm-diameter tubing is compared to that through conventional 4-mm tubing when connected to standard large-gauge intravenous cannulae. Lengths of intravenous tubing between 80 cm and 200 cm were tested in combination with 16 gauge, 14 gauge and 13 gauge intravenous cannulae. The results demonstrated that the use of 3-mm-diameter infusion sets, or the inclusion of even short lengths of 3-mm tubing in an infusion system, limits the maximum flow that can be delivered through a cannula of size 16 gauge or larger. The reduced performance of the 3-mm tubing makes administration systems incorporating even short lengths of this diameter of tubing unsuitable in emergency situations and locations where rapid infusion of fluids is vital.

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This study compares the quality and duration of analgesia in two groups of patients aged between 1 and 13 years who received either caudal anaesthesia with plain bupivacaine 0.25% or an iliohypogastric and inguinal nerve block combined with skin infiltration using bupivacaine 0.25% with adrenaline 1:200,000. The results indicate no significant difference in the duration or quality of the analgesia provided by the two techniques. There was no difference in the incidence of vomiting or the time of first micturition between the two groups.

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Human immunodeficiency virus (HIV), the retrovirus that causes the acquired immunodeficiency syndrome, is cytopathic for CD4+ T cells and binds to these cells via a complex of the 110,000 m.w. viral-envelope glycoprotein, gp110, and the CD4 molecule. We treated virus with several physical, chemical, and enzymic agents to determine their effect on the capacity of HIV to bind to the CD4+ T cell line, CEM. Reduction and alkylation (but not alkylation alone) and trypsin digestion (but not glycolytic enzyme digestions) of HIV destroyed its capacity to bind. If the tertiary protein structure conferred by disulfide bonding is not disrupted, the tertiary and secondary conformations dependent on noncovalent forces appear to be thermodynamically favored, because treatment with denaturants such as sodium dodecyl sulfate, 8 M urea, alcohol, or heat (56 degrees C or 65 degrees C for 30 min) followed by removal of the denaturants did not affect binding. Irreversible denaturation and loss of binding occurred after heating at 100 degrees C for 10 min. HIV binding to CD4+ T cells was inhibited either by murine monoclonal antibodies to the CD4 molecule or by human polyclonal or murine monoclonal antibodies to the gp110 molecule. On the basis of results of binding inhibition obtained with a panel of alpha-CD4 monoclonal antibodies, the receptor site for virus on the CD4 molecule was mapped to the amino-terminal portion of the molecule. Four candidate alpha-CD4 monoclonal antibodies that were potent inhibitors of virus binding (OKT4A, OKT4D, OKT4F, and Leu-3a) were examined for the possibility that their binding sites (idiotopes) might share structural and conformational similarity with the CD4-binding site on gp110. Polyclonal human or rabbit anti-HIV sera (that reacted with gp110 and inhibited virus binding) did not react with or inhibit the binding of these four alpha-CD4 monoclonal antibodies. Conversely, rabbit anti-idiotypic sera raised against each of the four candidate CD4 monoclonal antibodies did not react with virus or inhibit virus binding to CD4+ T cells. Further search or different approaches may yet yield an idiotype that is a structural and conformational "internal image" of the CD4-binding site of virus.

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We explored the possibility that normal human monocytes can be infected with the retrovirus human T lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV). The T4 antigen, believed to be the receptor for HTLV-III/LAV binding to CD4 cells, is found on monocytes at low levels. Anti-T4A, which recognizes an epitope on the T4 molecule, inhibits viral binding to monocytes, and virus inhibits anti-T4A binding, although inhibition in both cases is not total. Virus particles were detected in HTLV-III/LAV-pulsed monocytes by electron microscopy as early as 10 min and for up to 3 days after inoculation, although budding virus was not observed. Monocytes were exposed to virus, were washed, and were cultured. Monocyte cultures were monitored by conventional assays for virus replication: immunofluorescence detection of cytoplasmic virus, supernatant reverse transcriptase activity, and supernatant virus antigen. These assays were either negative or at the lower limits of positivity. However, the amount of infectious virus was shown to increase over time in monocyte cultures by harvesting monocytes or their culture supernatants and titrating them into assay cultures containing stimulated T cells. Virus recovery from monocytes and virus recovery from T cells differed both quantitatively and qualitatively. Recovery from T cells and T cell supernatants peaked at 3 to 6 days and declined thereafter. Recovery from monocytes and monocyte supernatants increased over time in culture and never attained the levels of T cell cultures. Taken together, these studies indicate that HTLV-III/LAV binds to monocytes via the T4 molecule and enters the cells. Infectious virus is retained and increases with time in infected monocyte cultures. Both viral binding and infection are at low levels compared with levels in T cells. Unlike the usual infection of T cells characterized by high level virus replication with cell depletion, the infection appears to be persistent in monocytes.

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In cultures of normal human lymphocytes infected with the human retrovirus HTLV-III/LAV, detectable cytoplasmic virus appears and then disappears in a proportion (1 to 10%) of cells, followed by release of virus detected by particulate reverse transcriptase activity, virus antigen assay, and infectivity titer. Virus infection is associated with loss of detectable T4 antigen on infected cells and, ultimately, complete loss of T4+ cells from the culture. Residual non-T4+ cells are not susceptible to a second infection with HTLV-III/LAV, and in cultures of separated cell populations, substantial virus replication occurred in T4+ T cells and minimally, if at all, in non-T4+ cells. We could not detect a disproportionate loss of cell surface phenotype (other than T4) in comparison of infected and noninfected cultures of lymphocytes or purified T4+ T cells when these cultures were monitored with a panel of monoclonal antibodies that detect the major mononuclear cell types (alpha-T11, alpha-T3, alpha-Mo2, alpha-B1), functional T cell subsets (alpha-T8, alpha-Leu-8, alpha-T17), or activated/proliferating cells (alpha-T10, alpha-Ia, alpha-T9, alpha-4F2, alpha-Tac). HTLV-III/LAV replication was quantitatively greatest in lymphocytes stimulated with phytohemagglutinin (PHA) and cultured in the presence of interleukin 2 (IL 2). Once activated by PHA, virus production in nondividing (irradiated) cells was similar to that in nonirradiated cells, but was substantially reduced if radiation was performed before PHA stimulation. Omission of PHA, IL 2, or both resulted in progressively lower amounts of virus replication. However, virus replication was detected and T4+ T cell depletion occurred in all cultures, regardless of medium supplement or radiation. T4+ T cells absorb infectious virus, and the binding of HTLV-III/LAV to the surface of T4+ T cells, but not to non-T4+ cells, was directly demonstrated. Binding is equivalent in activated and nonactivated cells and at 4 degrees and 37 degrees C. Reciprocal inhibition of binding was observed with alpha-T4a monoclonal antibody and virus. Exposure of cells to alpha-T4a before and during HTLV-III/LAV inoculation inhibited subsequent virus replication. We conclude that T4+ T cells are the major target for HTLV-III/LAV replication, that this tropism is related to expression of the T4 antigen that serves as a binding site for virus, that infection is inexorable in T4+ T cells regardless of subset or activation state, and that the activation/proliferative state of the cells is not a necessary determinant of infectivity, but rather, determines the amount of replication that will ensue.

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We have compared T and B cell analyses using whole blood, separated lymphocytes, and separated, frozen, then thawed lymphocytes to see how long blood can be kept before separation and analysis. We also examined the effect of various anticoagulants and the effect of diluting blood in culture media on T and B cell analysis over time. We found that the whole blood method is a very reliable method for T and B cell analysis, even 4 days after the blood is drawn, provided that heparin or ACD is the anticoagulant used. Separated lymphocytes and cryopreserved lymphocytes from blood that was separated within 24 h of collection was satisfactory; however, results were less consistent if separation was delayed more than 24 h. For lymphocyte separation, blood collected in heparin or ACD held up better over time than did blood collected in EDTA, and dilution with either RPMI 1640 or McCoy's medium gave better lymphocyte separation in older blood.

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Unexplained, generalized lymphadenopathy in homosexual men, which can be a prodrome to the acquired immunodeficiency syndrome, is associated with impaired cell-mediated immunity, a low ratio of T helper-inducer to T suppressor-cytotoxic cells (defined by the T4 and T8 monoclonal antibodies), and hypergammaglobulinemia. We performed double-marker studies on T cells by using a panel of monoclonal antibodies (Ia, T17, TQ1, and Leu-8), which reportedly detect activation or functional subsets of the T4 and T8 T cell populations. The T4:TQ1- or T4:Leu-8- subset, which is the major helper subset for B cell responses, is normally represented in lymphadenopathy patients. A depression in the reciprocal subset, T4:TQ1+ or T4:Leu-8+, accounts for the T4 T cell defect. Similarly, the TQ1 and Leu-8 markers delineate the abnormality of T8 T cells: the T8:TQ1- or T8:Leu-8- subset is elevated, whereas the T8:TQ1+ or T8:Leu-8+ subset is normally represented. We found no evidence of excessive activation of T4 T cells by using the T17 or Ia monoclonal antibodies. We did find an overall increase in Ia-positive T cells; however, this was due to increased T8:Ia+ cells. In functional studies, immunoglobulin production induced by pokeweed was subnormal. Most lymphadenopathy patients had normal T helper cell function when combined with normal B cells. The dampened pokeweed responses could be partially explained by depression of the T4:TQ1+ (or T4:Leu-8+) subset (which has minor help-associated function) and/or greater than expected suppression. However, subnormal pokeweed responses could not be totally explained by immunoregulatory T cell abnormalities because we also found an intrinsic defect in the B cell responses of lymphadenopathy patients.

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