Z-scan studies of the nonlinear optical properties of gold nanoparticles prepared by electron beam deposition

This paper details the fabrication process for placing single-layer gold (Au) nanoparticles on a planar substrate, and investigation of the resulting optical properties that can be exploited for nonlinear optics applications. Preparation of Au nanoparticles on the substrate involved electron beam deposition and subsequent thermal dewetting. The obtained thin films of Au had a variation in thicknesses related to the controllable deposition time during the electron beam deposition process. These samples were then subjected to thermal annealing at 600°C to produce a randomly distributed layer of Au nanoparticles. Observation from field-effect scanning electron microscope (FESEM) images indicated the size of Au nanoparticles ranges from ∼13 to ∼48  nm. Details of the optical properties related to peak absorption of localized surface plasmon resonance (LSPR) of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear effects on the fabricated Au nanoparticle layers where it strongly relates LSPR and nonlinear optical properties.

Frequency of potential therapeutic targets identified by immunohistochemistry (IHC) and DNA microarray (DMA) in tumors from patients who have progressed on multiple therapeutic agents

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An important question that arises when caring for patients referred for phase I clinical trials is, if one studied the patients’ tumors carefully enough, would there be targets in those patients’ tumors for which a therapeutic agent might already be available. Perhaps treating the patient with that therapeutic agent would be better than trying the phase I agent. To address that issue we have performed IHC assays for up to 13 targets (e.g. Her2/neu, ER, c-kit, etc.) as well as a two color Agilent oligonucleotide microarray with 17, 085 unique probes, on tumors from patients with advanced cancer who have exhausted conventional therapy and who were undergoing a procedure for a cancer related matter (e.g. obstruction, ascites, etc.). Ninety-one patients had excess tissue submitted from the procedure, immediately frozen and subjected to microarray analysis and had IHC performed on sections obtained from the paraffin blocks prepared as part of their standard surgical workup. IHC was considered positive if ≥ 30% of tumor cells were scored as +1 or greater staining. For microarray studies the gene expressions were called significantly increased or decreased if the fold change in expression relative to the nominal tissue of origin reference was significant at p≤0.001. For the 91 patients where frozen tumor was submitted 89 (98%) of them had RNA that was of excellent quality. The findings were a surprise in that IHC identified an average of 1.2 targets (for which a conventional therapeutic agent is available) per patient (range 0 - 4 targets). The DMA identified an average of 3.3 targets per patient (range 0 - 8 targets). Overall, a target was found for 89 (98%) of the patients. This data indicates that using IHC and DMA one can consistently find a potential target for which we have a therapeutic agent in patients’ tumors even thought they have progressed on prior therapies. This has implications for patients’ planning on participating in phase I clinical trials. It is important to conduct a prospective clinical trial to determine whether the targets discovered using IHC and DMA can be used to select therapy which will further benefit the patient who would otherwise be participating in a phase I clinical trial.

[Table: see text]

Mobile phones, heat shock proteins and cancer

There are several reports which indicate that electromagnetic radiation (such as from mobile phones) at non-thermal levels may elicit a biological effect in target cells or tissues. Whether or not these biological effects lead to adverse health effects, including cancer, is unclear. To date there is limited scientific evidence of health issues, and no mechanism by which mobile phone radiation could influence cancer development. In this paper, we develop a theoretical mechanism by which radiofrequency radiation from mobile phones could induce cancer, via the chronic activation of the heat shock response. Upregulation of heat shock proteins (Hsps) is a normal defence response to a cellular stress. However, chronic expression of Hsps is known to induce or promote oncogenesis, metastasis and/or resistance to anticancer drugs. We propose that repeated exposure to mobile phone radiation acts as a repetitive stress leading to continuous expression of Hsps in exposed cells and tissues, which in turn affects their normal regulation, and cancer results. This hypothesis provides the possibility of a direct association between mobile phone use and cancer, and thus provides an important focus for future experimentation.

Hemodynamic effects of Bosentan, an endothelin receptor antagonist, in patients with pulmonary hypertension

BACKGROUND

Few treatments are available for isolated pulmonary hypertension (PHT), which has a high morbidity and mortality. This trial was designed to assess the hemodynamic effects of bosentan, an endothelin receptor antagonist, in patients with PHT, in which local overproduction of endothelin-1 (ET-1) is thought to play a pathogenic role.

METHODS AND RESULTS

An open-label, dose-ranging study was performed in 7 female patients with primary PHT (n=5) or isolated PHT associated with limited scleroderma (n=2). Infusions of 50, 150, and 300 mg were administered at 2-hour intervals, and the hemodynamic responses were measured. Bosentan caused a dose-dependent fall in total pulmonary resistance (-20.0+/-11.0%, P=0.01) and mean pulmonary artery pressure (-10.6+/-11.0%, P>0.05). However, there was also a fall in the systemic vascular resistance (-26.2+/-12.8%, P<0.005) and mean arterial pressure (-19.8+/-14.4%, P<0.001). There was a slight increase in cardiac index (15+/-12%, P>0.05) and a dose-dependent rise in ET-1 but no significant change in other hemodynamic variables, gas exchange, or other vasoactive mediators.

CONCLUSIONS

Intravenous bosentan is a potent but nonselective pulmonary vasodilator at the doses tested, even in patients resistant to inhaled nitric oxide. Transient increases in plasma ET-1 were observed, consistent with a blockade of endothelial ET(B) receptors. Systemic hypotension and other significant events during the study indicate that its intravenous use in patients with severe PHT may be limited. Implications for future trial design and studies of chronic oral treatment are discussed.

Preclinical characterization of an anti-tat ribozyme for therapeutic application

A hammerhead ribozyme retroviral construct, denoted RRz2, targeting the coding region of the human immunodeficiency virus type 1 (HIV-1) tat gene, has shown itself to be effective in a range of test systems. Inhibition of the replication of HIV-1 IIIB and primary drug-resistant strains in pooled transduced CEMT4 cells was consistently found to be more than 80% compared with the control-vector transduced cells, whereas a mutant RRz2 gave approximately 45% inhibition. A multiple HIV-1 passage assay showed the absence of emergence of mutations within the specific viral RNA ribozyme target sequences. This lack of generation of ribozyme "escape mutants" occurred despite the almost complete disappearance of a HIV-1 quasi-species in the testing virus. When RRz2 was tested in peripheral blood lymphocytes (PBLs) from HIV-1-infected patients, paired analysis showed that cell viability in the ribozyme-transduced HIV-1-infected PBLs was significantly higher than that in the vector-transduced cells. This difference in viability (vector versus RRz2) was not observed in PBLs from non-HIV-1-infected donors. Taken together, these results indicate that the transfer of an anti-HIV-1 ribozyme gene into human T lymphocytes could have major impact on viral replication and T cell viability in the HIV-1-infected individual.

Systemic sclerosis in DRw52-positive silica-exposed males: a case report

The aims of this paper were to describe clinical and laboratory details of 4 siblings, of whom 2 have systemic sclerosis and to describe this family in the context of reported cases of familial systemic sclerosis. The proband and his affected male sibling share the tissue typing antigens: HLA11, B57, DR13, DRw52,- and DQ2,6. Both were concordant for gender, silica exposure, marital status, migration history and antinuclear factor status but discordant for systemic sclerosis subtype, age at disease onset and ENA status. One non-affected sibling had no disease despite concordance for gender, HLA status, silica exposure, marital status, and migration history.

Australian Leukaemia Study Group myeloma II: a randomized trial of intensive combination chemotherapy with or without interferon in patients with myeloma

The Australian Leukaemia Study Group has performed a randomized trial of interferon alpha-2A (Roferon-A) as a co-induction agent together with intensive combination chemotherapy and as maintenance following completion of 12 cycles of induction treatment. When used as a co-induction agent, interferon-alpha did not improve response rates, time-to-treatment failure, or overall survival. Patients who had interferon together with intensive combination therapy (PCAB: prednisone 60 mg/m2 days 1-5, cyclophosphamide 600 mg/m2 day 1, BCNU 30 mg/m2 day 1, doxorubicin 30 mg/m2 day 1, repeated every 28 d for a total of 12 cycles) had more leucocyte and granulocyte toxicity and received a lower dose intensive of cytotoxic drugs than those patients who received PCAB without interferon. There was a trend towards prolongation of plateau phase which did not reach significance. Interferon, however, did improve the survival of patients who achieved plateau; for those patients interferon was associated with a 33% decrease in the rate of death after adjusting for initial beta-2 microglobulin level.

Bacillus Calmette-Guérin plus intravesical interferon alpha-2b in patients with superficial bladder cancer

OBJECTIVES

Bacillus Calmette-Guérin (BCG) and interferon alpha-2b (IFN alpha 2b) have been used individually for the treatment of bladder cancer. We used a low dose of BCG combined with IFN alpha 2b to determine the safety and to assess the efficacy of this combination therapy.

METHODS

A study of 12 patients with superficial bladder cancer evaluated the safety and efficacy of a combination of low-dose BCG and IFN alpha 2b, given weekly for 6 weeks. Three patients were assigned to each of four groups in which 60 mg of BCG was combined with 10, 30, 60, or 100 x 10(6) IU of IFN alpha 2b.

RESULTS

The combination BCG/IFN alpha 2b therapy was well tolerated, with adverse effects being mild to moderate and resolved at the end of treatment. At 12 months post-treatment there has been no tumor progression. Two patients with previous multifocal transitional cell carcinoma have had solitary recurrences. One patient has had recurrent carcinoma in situ.

CONCLUSIONS

This preliminary study found combination BCG/IFN alpha 2b induction therapy to be safe and well tolerated. These early results show a high response rate, but efficacy can only be determined with Phase II and III studies.

Acute hemodynamic responses to inhaled nitric oxide in patients with limited scleroderma and isolated pulmonary hypertension

BACKGROUND

Inhaled nitric oxide (NO) is a selective pulmonary vasodilator that reduces pulmonary vascular resistance (PVR) in patients with primary pulmonary hypertension. Their responses to inhaled NO predict their responses to other vasodilators, such as prostacyclin, and provide an estimate of the "fixed" component of their increased PVR. Some patients with limited cutaneous systemic sclerosis develop isolated pulmonary hypertension with a similar clinical course. Therefore, we have measured the acute hemodynamic response to inhaled NO in such patients.

METHODS AND RESULTS

Seven patients were studied during inhalation of increasing concentrations of NO (0 to 80 ppm). Complete hemodynamic data were collected on five patients. They demonstrated a selective, dose-dependent, and rapidly reversible fall in PVR (34%) and mean pulmonary artery pressure (17%). There was a nonsignificant increase in cardiac index but no change in mean arterial pressure or systemic vascular resistance. The mean right atrial pressure fell (27%), but there was no change in pulmonary artery occlusion pressure. Of the seven patients, five responded to inhaled NO ( < or = 40 ppm) with a decrease in total pulmonary resistance of at least 20%.

CONCLUSIONS

Inhaled NO is an effective and selective pulmonary vasodilator in a significant number of patients with pulmonary hypertension associated with limited cutaneous systemic sclerosis. It may be useful in determining the potentially reversible contribution to the increased PVR and should be considered for patients with acute pulmonary vascular crisis.

Primary infection with zidovudine-resistant human immunodeficiency virus type 1 does not adversely affect outcome at 1 year. Sydney Primary HIV Infection Study Group

Human immunodeficiency virus type 1 (HIV-1) variants with reduced in vitro sensitivity to zidovudine, conferred by specific mutations in the viral reverse transcriptase, emerge during prolonged therapy. Late-stage disease and declining CD4 cell count are associated with more rapid emergence of these resistant variants. Isolates of HIV-1 from seroconverters were screened for the zidovudine-resistance marker mutation at codon 215. HIV-1 with the altered genotype was detected in 5 (8.2%) of 61 patients soon after onset of symptomatic primary illness and from the sex partner of 1 patient. These transmitted resistant viruses were either replaced by strains susceptible to zidovudine within a few months of infection or persisted for up to 1 year in the absence of prolonged zidovudine therapy. The resistant genotype persisted in 3 of 5 seroconverters but in 2 patients had reverted to wild type at 48 and 52 weeks. Primary infection with zidovudine-resistant variants of HIV-1 was not associated with a more severe symptomatic primary illness or more rapid CD4 cell decline at 1 year after infection.

Managing HIV. Part 3. Mechanisms of disease. 3.2 How HIV produces immune deficiency

Initially, the immune system controls HIV infection, but over time the virus depletes the population of CD4+ T cells and disturbs the homoeostasis and function of other cells in the immune system. Extensive destruction of the immune system eventually leaves the body defenceless.

Both in vitro and in vivo irradiation are associated with induction of macrophage-derived fibroblast growth factors

Fibrosis in the lung directly underlying the field of irradiation is an almost universal long term sequelae of thoracic irradiation. It is assumed to represent the consequence of direct damage to local tissues and/or vascular endothelium by ionizing radiation. This view, however, is not in keeping with our current understanding of fibrotic processes, which suggest that growth factors for fibroblasts (including platelet-derived growth factor (PDGF), insulin-like growth factor I (IGF-I)) and cytokines stimulating collagen synthesis (notably transforming growth factor-beta) are largely responsible for this process. Since a major source of these factors is the macrophage, present in large numbers within the lung, it appeared possible that radiation-induced fibrosis might be mediated by similar mechanisms. Therefore, a study was designed to determine, first, whether in vitro irradiation of mononuclear phagocytes could induce the release of growth factors for fibroblasts. Second, we wished to ascertain whether these same growth factors might also be secreted by bronchoalveolar cells from humans who had undergone in vivo thoracic irradiation. The results of this study indicate that irradiation of a number of different types of mononuclear phagocytes resulted in the dose-dependent synthesis and release of several growth factors for fibroblasts, including PDGF, tumour factor-alpha (TNF-alpha) and IGF-I. Further, cells obtained by bronchoalveolar lavage from patients undergoing thoracic radiation spontaneously released PDGF following irradiation. These findings strongly support the contention that synthesis and release of macrophage-derived growth factors for fibroblasts (particularly PDGF and IGF-I) occur after thoracic irradiation and play a significant role in the pathogenesis of irradiation-induced pulmonary fibrosis in humans.

Quinolinic acid production is related to macrophage tropic isolates of HIV-1

We sought to determine whether the neurotoxin quinolinic acid (QUIN) was produced by macrophages or lymphocytes infected with isolates of HIV-1 with varying degrees of macrophage tropism derived from patients with varying stages of AIDS dementia complex (ADC). Highly macrophage tropic isolates and minimally macrophage tropic isolates were used to inoculate macrophages and QUIN production was measured. Similarly, QUIN production from macrophages was monitored using a purified cell free highly macrophage tropic isolate and laboratory isolates SF33 and SF2. Each of these experiments was also performed with lymphocytes. We found that macrophages infected with macrophage tropic isolates of HIV-1 led to QUIN production while lymphocytes did not produce QUIN. The ability of the HIV-1 infected macrophages to produce QUIN was related to the viral inoculum and the degree of macrophage tropism of the isolate. The severity of ADC in the patient from whom a particular isolate was derived was not per se a determining factor for QUIN production. Purified cell free ADC isolates also led to QUIN production by macrophages thereby suggesting that HIV-1 infection alone is capable of inducing QUIN production.

Antiproliferative effects of bacillus Calmette-Guerin and interferon alpha 2b on human bladder cancer cells in vitro

Direct inhibitory effects of bacillus Calmette-Guérin (BCG) and interferon alpha 2b (IFN alpha 2b) on six human bladder carcinoma cell lines, UCRU-BL-13, UCRU-BL-17, UCRU-BL-28, 5637, T24 and J82, were studied using an in vitro proliferation assay. Effects on proliferation following exposure to BCG or IFN alpha 2b were analysed by [3H]thymidine incorporation over 7 days. BCG had an antiproliferative effect on all bladder lines, while sensitivity to IFN alpha 2b varied greatly, being as remarkably low as 1 U/ml for some lines. The antiproliferative effect was greatest when cells were exposed continuously to either agent, but was still evident with a limited exposure. When clinical concentrations were simulated in vitro, BCG+IFN alpha 2b was more effective than BCG alone and as effective as a double BCG concentration. We conclude that, in addition to their immunomodulatory effects, BCG and IFN alpha 2b directly inhibit the proliferation of human bladder cancer cells, and often at extremely low concentrations.

Primary structure of the V3 region of gp120 from sequential human immunodeficiency virus type 1 isolates obtained from patients from the time of seroconversion

V3 loop sequences were compared from 5 human immunodeficiency virus type 1 (HIV-1)-infected patients over time. Three patients remained asymptomatic and 2 became symptomatic with large decrease in CD4 cell counts. The patient isolates were previously evaluated for phenotypic and antigenic properties and had different sensitivities to serum neutralization and changes in phenotype. This study showed a number of amino acid changes for the 2 symptomatic patients, each of whom progressed to AIDS during the study. The only amino acid substitution consistently associated with reduced CD4 cell counts, cytopathic effect, and progression to AIDS was Arg at position 11. Specific amino acid changes could not be correlated with increasing serum neutralization resistance or cytotropism changes. Increased loop charge was associated with a switch from macrophage to T cell tropism and a decrease in the number of CD4 cells. The study shows the importance of naturally occurring mutations in the V3 loop in controlling the biologic properties of HIV-1.

Expression of cytokine genes in T cell leukemias

Normal T cells secrete cytokines which have important effects on a wide range of other cells. In the present study, the expression of IL-2, IL-4, IL-5, IL-10 and IFN-gamma was assessed in PBMC from 3 cases of T cell leukemia, using reverse transcription and polymerase chain reaction (RT-PCR). The major difference between the leukemia cases and control PBMC samples was that, without in vitro stimulation, IFN-gamma was much more readily detected in 2 of the leukemia cases. IL-2 and IL-5 mRNA were also detected in 2 of the patients but not in the other samples. IL-4 mRNA was not detected in any unstimulated sample, whereas IL-10 was always present. After polyclonal stimulation in vitro, mRNA for all these cytokines was detected in all samples. Thus cytokine expression, particularly of IFN-gamma, may be more prominent in PBMC from adult T cell leukemia cases than in controls.

Effects of primary HIV-1 infection on subsets of CD4+ and CD8+ T lymphocytes

OBJECTIVE

To analyse changes in T-lymphocyte subsets in patients with primary HIV infection and to determine their specificity (and therefore their diagnostic utility) by comparing these changes with those seen in other acute illnesses as well as in HIV-uninfected patients.

METHODS

T-lymphocyte subsets were analysed by two- and three-colour flow cytometry, and compared between HIV seroconverters (n = 16), HIV-infected (n = 18) and uninfected (n = 33) controls, patients with infectious mononucleosis (n = 7), and patients suspected clinically of having primary HIV infection but who were later found to be uninfected (referred to as HIV non-converters; n = 17).

RESULTS

CD4+ lymphocyte counts were significantly lower in HIV seroconverters (mean, 444 x 10(6)/l) than in the HIV non-converters (793 x 10(6)/l; P = 0.003), HIV-seronegative controls (888 x 10(6)/l; P < 0.0001) and, to a lesser extent, those with mononucleosis (694 x 10(6)/l; P = 0.045). The reduction in CD4+ lymphocytes occurred in both the CD45RA+ (55%) and CD45R0+ (33%) subsets. CD8+ lymphocyte counts were significantly higher in HIV seroconverters (942 x 10(6)/l) than in HIV non-converters (570 x 10(6)/l; P = 0.003) and seronegative controls (467 x 10(6)/l; P < 0.0001), but significantly lower than in the mononucleosis group (3682 x 10(6)/l; P = 0.004). The CD8+ cells in the HIV seroconverters had increased coexpression of CD45R0, human leukocyte antigen (HLA)-DR, CD38 and CD11a/CD18. The mean CD4: CD8 ratio in the HIV seroconverters was 0.49, versus 1.52 in the non-converters (P < 0.0001), 2.08 in the seronegative patients (P < 0.0001) and 0.37 in the mononucleosis patients (P > 0.2).

CONCLUSIONS

Primary HIV infection is characterized by a depletion of CD4+ lymphocytes, especially of the CD45RA+ phenotype, and by an increase in CD8+ lymphocytes with an activated phenotype; the latter was also seen in patients with infectious mononucleosis but not in HIV non-converters or HIV-seronegative patients. Patients suspected clinically of having primary HIV infection but with normal T-cell phenotype are less likely to have primary HIV infection. These phenotypic changes, as well as an inverted CD4: CD8 ratio, can readily distinguish patients with primary HIV infection from HIV-uninfected patients except those with infectious mononucleosis. Therefore, T-cell-subset enumeration may be useful in the diagnosis of primary HIV infection.

Bacillus Calmette-Guerin (BCG) enhances monocyte- and lymphocyte-mediated bladder tumour cell killing

A cytotoxicity assay was used to study the action of bacillus Calmette-Guerin (BCG) and cytokines on four human bladder cancer cell lines. Monocytes and lymphocytes from peripheral blood were incubated with or without BCG or cytokines for 24 h, after which [3H]thymidine-labelled target cells were added and the 72 h percentage specific release determined. BCG had a direct cytotoxic effect against tumour cells and significantly enhanced monocyte/macrophage and enhanced lymphocyte cytotoxicity against one cell line (UCRU-BL-17). Supernatants (SNs) from BCG-activated monocytes/macrophages and lymphocytes increased the percentage specific release of [3H]thymidine from UCRU-BL-17 cells. Interferon alpha (IFN-alpha) and interleukin 2 (IL-2) were cytotoxic towards UCRU-BL-17. No synergy occurred between BCG and cytokines at the concentrations tested. The results suggest that BCG is superior to IFN-alpha, interferon gamma (IFN-gamma) and IL-2 in enhancing cell-mediated cytotoxicity.

Productive in vitro infection of human umbilical vein endothelial cells and three colon carcinoma cell lines with HIV-1

The objective of this study was to assess the ability of HIV-1 to establish an in vitro infection of primary human umbilical vein endothelial cells (HUVEC). The HUVEC and colon carcinoma cell lines were inoculated with different isolates of HIV-1 (HIV-1SF2, HIV-1Mck and HIV-1LAI) and productive viral infection was assessed by both the detection of p24 core antigen in the culture supernatants and the presence of specific spliced HIV mRNA. The infection which was detected in the inoculated HUVEC and all the colon carcinoma cell lines could not be blocked using an antibody targeted against the CD4 receptor. Furthermore, the HIV-inoculated HUVEC secreted elevated levels of IL-6 and this increase was found to be proportional to the size of the viral inoculum. No changes in the production of IL-1 beta, TNF-alpha, IFN-alpha and IFN-gamma were detected following HIV infection. The colon carcinoma cells, however, did not secrete increased levels of these cytokines following HIV-1 inoculation. These results confirm that non-CD4 expressing cells, such as endothelial cells and certain colon epithelial cells, serve as targets and reservoirs for HIV. Moreover, the production of IL-6 by HIV-infected endothelial cells may be a contributing factor to the aberrant immunoregulation associated with HIV infection in vivo.

Focal adhesion formation is associated with secretion of allergic mediators

Adherence of cells to the extracellular matrix via focal adhesions is known to modulate many cellular functions. However, the role of focal adhesions in the regulation of secretion is unclear. To examine this we have used the RBL-2H3 rat mast cell line, in which we and others have observed cytoskeletal rearrangements and increased cell spreading during secretion. All activators of secretion examined, whether acting specifically through or bypassing the IgE-receptor, induced the assembly of focal adhesions, as defined by the localization of vinculin and talin. The extent of focal adhesion formation correlated with the extent of secretion and the time course of secretion also correlated with that of the assembly of focal adhesions. To examine the mechanism by which focal adhesion formation occurred, the protein kinase C inhibitor bisindolylmaleimide was used. Bisindolylmaleimide caused complete inhibition of both secretion and focal adhesion formation induced by antigen or the calcium ionophore A23187. Although PMA did not induce secretion, it induced focal adhesion assembly which was inhibited by bisindolylmaleimide. The inhibitor had no effect on secretion or focal adhesion formation induced by the ATP analogue, ATP gamma S in permeabilized cells, indicating ATP gamma S acts after the activation of protein kinase C in the secretory pathway. These data provide novel evidence that the formation of focal adhesions may have a role in the process of secretion from mast cells.

Neutralizing antibodies against sequential autologous human immunodeficiency virus type 1 isolates after seroconversion

The emergence of human immunodeficiency virus type 1 (HIV-1) variants with different sensitivities to serum neutralization and biologic phenotype was studied for 2-5 years after primary HIV-1 infection in 5 subjects. In 3 subjects, the initial virus isolate from seroconversion could be neutralized by autologous serum, but isolates obtained at two subsequent times exhibited reduced sensitivity to serum neutralization, decreased replication in primary macrophages, and increased ability to induce syncytia. Two of these 3 subjects progressed to AIDS and died. Sequential virus isolates from the other 2 subjects showed variability in sensitivity to serum neutralization or biologic features. These patients remained relatively stable in clinical status. Thus, viruses isolated at seroconversion appear to be either non-syncytium-inducing, strong macrophage-tropic, serum neutralization-sensitive phenotypes with stable clinical status or to have escaped neutralization by autologous sera over time, have reduced macrophage tropism and increased syncytia formation, and be associated with disease progression.

Circulating endothelin-1 levels in systemic sclerosis subsets--a marker of fibrosis or vascular dysfunction?

OBJECTIVE

To investigate the circulating levels of endothelin-1 (ET-1) in serum (sET-1) in patients with pulmonary disease [pulmonary fibrosis (PF) and pulmonary hypertension (PHT)], and renal involvement [hypertensive renal crisis (HRC)] in the 2 major subsets of systemic sclerosis (SSc) in order to determine the significance of sET-1 levels in relation to specific organ involvement or to the underlying pathogenic mechanisms of vascular damage and fibrosis.

METHODS

In addition to the measurement of ET-1 in serum using a competitive radioimmunoassay, the circulating levels of angiotensin converting enzyme (ACE) and plasma von Willebrand factor (vWF) were measured as markers of endothelial damage in the various disease groups.

RESULTS

Levels of sET-1 were significantly increased in 64 patients with diffuse systemic sclerosis (dSSc) and 17 patients with primary Raynaud's phenomenon (RP) compared with 22 healthy individuals. sET-1 levels were equally elevated in diffuse cutaneous disease (dcSSc) with only fibrotic dermal or lung pathology compared with patients with additional PHT or HRC crisis. These observations were in marked contrast to the sET-1 levels seen in patients with the limited cutaneous form of SSc (lcSSc) where only patients with lcSSc with hypertensive lung or renal disease had significantly higher levels of sET-1 than comparable lcSSc patients with only fibrotic dermal and lung disease. sET-1 levels were additionally found to correlate with plasma vWF, skin fibrosis (skin score) and duration of disease in patients with SSc.

CONCLUSION

The presence of significantly raised sET-1 levels in patients with dcSSc with widespread fibrosis and patients with lcSSc with hypertensive disease and the relationship seen between sET-1 levels and markers of fibrosis and vascular damage suggest that ET-1 may be important in the pathogenesis of both the fibrotic and vascular manifestations in SSc.

Immunohistological assessment of cutaneous drug hypersensitivity in patients with HIV infection

The pathogenesis of drug hypersensitivity in patients with HIV infection is unknown. To study further the nature of hypersensitivity, the histopathological features of morbilliform drug hypersensitivity reactions were examined in a group of HIV-infected patients. Skin sections from 23 HIV-infected subjects with morbilliform drug hypersensitivity reactions were examined by light microscopy, direct immunofluorescence and immunohistochemistry, to determine the nature of the inflammatory infiltrate and the role of immunoglobulin, complement and cytokines. The principal light microscopic findings were spongiosis, hydropic generation of the basal layer, civatte bodies, an epidermal lymphocytic infiltrate (48%), and a perivascular dermal infiltrate of lymphocytes (87%) and macrophages (52%). Two patients had findings consistent with toxic epidermal necrolysis. Immunohistochemistry demonstrated that the lymphocytic infiltrate consisted of CD8+, HLA-DR+ T lymphocytes (some of which also stained for CD38), a marked depletion of epidermal Langerhans cells (90%), and strong cytoplasmic staining of keratinocytes for IL-6 (60%), IL-1 beta (50%), tumour necrosis factor-alpha (TNF-alpha) (45%) and to a lesser degree, interferon-gamma (IFN-gamma) (35%). Immunofluorescence did not demonstrate any significant deposition of immunoglobulin or complement. The histological findings were independent of the responsible drug, the duration of either therapy or the rash, and of peripheral blood CD4+ and CD8+ cell counts. These findings suggest that activated CD8+ lymphocytes and perhaps epidermal production of cytokines are involved in the pathogenesis of cutaneous drug hypersensitivity in HIV-infected patients. The common histological features, regardless of the causative drug, suggest a common pathogenesis.

Scleroderma and silicone breast implants

A 43-yr-old caucasian female presented in July 1992 with an explosive onset of diffuse scleroderma following general anaesthesia for orthopaedic surgery. Her environmental exposures included silicone breast prosthetic surgery and silica exposure, both preceding development of scleroderma. She was DR5-negative, DRw52 positive. All currently available literature relating to breast implants and scleroderma is reviewed and the conclusion drawn that, for currently documented US data, there is no evidence to suggest that patients having had breast augmentation have rates of scleroderma higher than expected to chance alone. However the cause-effect relationship between silicone and scleroderma/other connective tissue disease requires, not just anecdotal reports, but a rigorously designed study.

Acetylation phenotype and cutaneous hypersensitivity to trimethoprim-sulphamethoxazole in HIV-infected patients

OBJECTIVE

Hypersensitivity to trimethoprim-sulphamethoxazole (TMP-SMX) is more common in patients with HIV infection. In non-infected patients, TMP-SMX hypersensitivity is more common in those with a slow acetylator phenotype. This study was conducted to determine whether the slow acetylation phenotype is associated with an increased risk of hypersensitivity to TMP-SMX in patients with HIV infection.

METHODS

Acetylation phenotype was determined in 28 HIV-infected subjects, of whom 16 had prior TMP-SMX hypersensitivity and 12 had received long-term TMP-SMX therapy without hypersensitivity, as well as in 29 healthy controls. Acetylation phenotype was determined by measuring the ratio of two urinary caffeine metabolites, 5-acetylamino-6-amino-3-methyl uracil (AAMU) and 1-methylxanthine (1-MX), after ingestion of a single 200 mg dose of caffeine.

RESULTS

Of the 28 HIV-infected subjects, 20 (71%) expressed a slow acetylation phenotype and eight (29%) a fast phenotype. By comparison, of the 29 healthy controls, 15 (52%) expressed a slow phenotype (P = 0.11). Of the 16 HIV-infected subjects with prior TMP-SMX hypersensitivity, 15 (94%) had a slow acetylation phenotype, whereas only five out of 12 (42%) non-hypersensitive subjects had a slow acetylation phenotype (P < 0.01).

CONCLUSIONS

A slow acetylation phenotype is a risk factor for hypersensitivity to TMP-SMX in HIV-infected subjects.

A confocal microscopy study of anticytoskeletal antibody activity in patients with connective tissue disease

The significance of the presence of antibodies to cytoskeleton proteins in patients with connective tissue diseases is not clear, as there is a high level of these antibodies in healthy controls. In an attempt to improve the visualization of the immunofluorescence binding pattern of autoantibodies to cytoskeletal structures in cultured fibroblasts, we have used confocal microscopy. Of the 256 serum samples tested, 155 (61%) WERE reactive with cytoplasmic structures. These reactive samples could be divided into seven patterns of binding, as determined by double-blind examination of single-section confocal images. While confirming the results of previous immunofluorescence studies which have shown that autoantibodies that bind to filamentous structures in the cytoplasm of cultured cells are common in patients with connective tissue diseases, we were able to identify three patterns of cytoskeletal binding which may be useful as an adjunct to other tests for the diagnosis of some connective tissue diseases, in particular systemic sclerosis (scleroderma) and rheumatoid arthritis/Sjogren's syndrome. None of the seven patterns was exclusive to a particular disease. We conclude that confocal microscopy may be of limited use as an adjunct to other serological assays in the diagnosis of some forms of connective tissue disease.

In vitro cytotoxicity as a marker of hypersensitivity to sulphamethoxazole in patients with HIV

Hypersensitivity to trimethoprim-sulphamethoxazole (TMP-SMX) in patients with HIV infection may be a result of either immune dysregulation, a direct cytotoxicity of the SMX-hydroxylamine metabolite (SMX-HA) (rather than SMX per se), or glutathione deficiency. We evaluated the in vitro cytotoxicity of SMX and SMX-HA to peripheral blood mononuclear cells (PBMC) of HIV-infected subjects to determine if the degree of in vitro cytotoxicity is associated with hypersensitivity, whether glutathione inhibits cytotoxicity, and whether in vitro cytotoxicity is predictive for the development of hypersensitivity. Given that fever is often a prominent feature of hypersensitivity, we also assessed whether SMX or SMX-HA could induce the in vitro production of IL-1 beta, IL-6 or tumour necrosis factor-alpha (TNF-alpha) by PBMC. The cytotoxicities of SMX and SMX-HA to PBMC were assessed in 45 HIV-infected patients with prior TMP-SMX therapy, and in eight HIV- controls. Twelve HIV-infected subjects were studied prospectively before primary Pneumocystis carinii pneumonia (PCP) therapy or rechallenge with TMP-SMX in previously hypersensitive subjects. Cytokine production was measured in four hypersensitive and two non-hypersensitive HIV-infected subjects, and three HIV-uninfected controls. The cytotoxicity of SMX-HA to PBMC was significantly greater in the 22 HIV-infected patients with prior hypersensitivity than both the 23 HIV-infected patients without hypersensitivity and the control group. Cytotoxicity was significantly reduced by glutathione only in the hypersensitive group. SMX did not induce cytotoxicity in any group. In 12 subjects studied prospectively, SMX-HA cytotoxicity was also significantly greater in those with subsequent hypersensitivity. Exposure of PBMC to SMX-HA resulted in a modest increase in the production of IL-6, IL-1 beta and TNF-alpha, although no major difference was detected between subjects with or without hypersensitivity. These data suggest that SMX-HA and glutathione deficiency are involved in the pathogenesis of hypersensitivity to TMP-SMX in HIV-infected patients, and that in vitro cytotoxicity could be useful in the diagnosis of hypersensitivity and predicting its likelihood.

Antibody penetration of viable human cells. II. Anti-RNP antibodies binding to RNP antigen expressed on cell surface, which may mediate the antibody internalization

As U1 small nuclear ribonucleoprotein (U1 snRNP2) has a crucial role in pre-mRNP splicing, the interaction of anti-RNP antibody with snRNP within viable lymphocytes may profoundly influence cell functions. We have shown that antibody can penetrate viable human lymphocytes, and anti-RNP antibodies enter more cells than other anti-nuclear antibodies or control IgG. In order to study the in vitro interaction of anti-RNP antibodies with viable cells, T lymphocytes were metabolically labelled with 35S-methionine, then incubated with the antibodies and washed. A set of 35S-labelled cell-associated snRNP polypeptides A, B'/B, C and D were found to bind to both monospecific human polyclonal anti-RNP IgG (human anti-RNP IgG) and a mouse monoclonal anti-RNP antibody (2.73), indicating that anti-RNP antibodies interacted with RNP antigen inside or/and on the surface of viable cells. To investigate antibody binding to RNP antigen on the cell surface, the cell surface proteins were either iodinated with 125I or the cells processed for immunoelectron microscopic studies after incubation with MoAb. At least seven 125I-labelled polypeptides on the cell surface were found to be immunoprecipitated by the anti-RNP MoAb which have similar molecular weights to U snRNP polypeptides 70K, A, B, D, E, F, and G. The immunoelectron microscopic studies showed that the gold particles formed clustered patches on the cell membrane. Further studies suggested that RNP antigen bound to the cell surface, and the RNP binding structure was probably a heterodimer receptor. This study provides evidence to suggest that anti-RNP antibody entry into viable cells may be mediated by interaction with RNP antigen expressed on the cell surface.

Interleukin-5 is necessary for eosinophilia induced by cyclophosphamide in immunized mice

Interleukin-5 (IL-5) has an important role in the induction of eosinophilia, which is associated with parasitic infestations and with allergic conditions, and which can be induced in a number of experimental systems. One of these model systems involves the administration of cyclophosphamide (CY) to immunized animals. In order to assess the role of IL-5 in this model, eosinophilia was induced in vivo and cell suspensions of spleens or lymph nodes were stimulated in vitro. IL-5 protein secretion was detected by bioassay using an IL-5-dependent cell line (T88-m), and mRNA was assessed by reverse transcription and polymerase chain reaction (RT-PCR). The production of IL-5 protein and mRNA were greatly enhanced in the cells from mice given CY with ovalbumin (OVA), compared with mice given either agent alone. IL-5 protein and mRNA were increased both in spleen and in lymph node cells, and in response either to OVA or to polyclonal stimuli. Further evidence for the importance of IL-5 in this model of eosinophilia was provided by experiments with monoclonal antibodies (mAb) in vivo. A single injection of an IL-5-specific mAb at the time of immunization completely abolished the eosinophilia. By contrast, a monoclonal antibody to IL-4 had no effect. These experiments indicate that IL-5 is required for the eosinophilia induced by CY in immunized mice.

Augmentation of HIV-specific lymphoproliferation in HIV-infected individuals by TraT: a novel T-cell immunopotentiating agent

OBJECTIVE

To evaluate the potential of TraT to restore HIV-specific cell-mediated immunity.

DESIGN

CD4+ T cell-associated antiviral and recall antigen-specific lymphoproliferative responses are generally impaired or absent in HIV-infected individuals.

METHODS

Using peripheral blood mononuclear cells (PBMC) from a group of asymptomatic and symptomatic HIV-infected individuals, we compared the immunomodulatory effects of exogenous interleukin-2 (IL-2) with the effects elicited by the bacterial integral membrane protein, TraT.

RESULTS

Exogenous IL-2 enhanced lymphoproliferation induced by an immunodominant synthetic HIV gp41 analogue, gp41[8] (amino acids 593-604), in four out of 10 asymptomatics and six out of 19 symptomatics. In contrast, TraT acted synergistically with gp41[8] to augment HIV-specific proliferation with higher frequency and greater magnitude than exogenous IL-2. Moreover, this TraT-mediated enhancement of HIV-specific lymphoproliferation occurred in the majority of HIV-infected individuals, irrespective of CD4+ T-cell count in peripheral blood or disease status, and thus appears not to be major histocompatibility complex-restricted. TraT also augmented lymphoproliferation induced by well-known recall antigens and other less immunodominant HIV analogues.

CONCLUSIONS

These findings suggest that TraT, in combination with HIV-derived peptides, could be used to maintain or restore cell-mediated immune functions of HIV-infected individuals, as well as cellular immune functions in individuals suffering from other immunodeficiency disorders.

Radiation pneumonitis: a possible lymphocyte-mediated hypersensitivity reaction

OBJECTIVE

To determine if unilateral thoracic irradiation results in a lymphoid alveolitis in both irradiated and unirradiated lung fields.

DESIGN

A prospective, nonrandomized study.

PATIENTS

Women receiving postoperative radiotherapy for carcinoma of the breast were evaluated both before and 4 to 6 weeks after radiotherapy. Findings after radiotherapy in 15 asymptomatic patients were compared with findings in a group of patients with clinical radiation pneumonitis.

MEASUREMENTS

History, physical examination, chest radiograph, quantitative gallium lung scanning, respiratory function tests, bronchoalveolar lavage, and lavage lymphocyte subset analysis.

RESULTS

After irradiation, lavage lymphocytes increased significantly (34.5% versus 46.8%; P = 0.01) in the 17 patients studied prospectively. There was an associated reduction in vital capacity (102.5% versus 95.5%; P = 0.04). Comparison of results in patients before treatment, after treatment without clinical pneumonitis, and after treatment with clinical pneumonitis showed a dramatic increase in total lymphocytes after irradiation (6.3 versus 9.4 versus 35.2 million, respectively; P = 0.005), particularly in those with clinical pneumonitis. Only in those with clinical pneumonitis was this accompanied by an increase in the gallium index (3.7 versus 3.4 versus 9.0, respectively; P < 0.001). Vital capacity was also progressively reduced (102.5% versus 96.9% versus 76.7%, respectively; P = 0.04), as was diffusing capacity (98.6% versus 91.4% versus 72.6%, respectively; P = 0.003). No statistical differences existed between irradiated and unirradiated sides of the chest in either lavage or gallium lung scan studies.

CONCLUSION

In most patients, a lymphocytic alveolitis develops in both lung fields after strictly unilateral thoracic irradiation; this is more pronounced in patients developing clinical pneumonitis. These findings suggest that radiotherapy may cause a generalized lymphocyte-mediated hypersensitivity reaction.

The role of Epstein-Barr virus subtypes in human immunodeficiency virus-associated lymphoma

High grade B cell non-Hodgkin's lymphoma (NHL) is an increasingly important problem in individuals infected with the human immunodeficiency virus (HIV). Fifty percent of these tumours harbour the Epstein-Barr virus (EBV) and there is an equal frequency of EBV A and B-subtypes in the tumours. This contrasts with the recent report that only A-type EBV is associated with Hodgkin's disease. Such studies are challenging the traditional models of EBV-associated lymphomagenesis and showing the way for further studies in this field. This article reviews the studies of EBV subtypes in HIV-associated NHL and uses this new knowledge to discuss the role of EBV in lymphomagenesis.

Radionuclide hepatobiliary scanning in patients with AIDS-related sclerosing cholangitis

Biliary disease, primarily manifesting as papillary stenosis or sclerosing cholangitis, is being increasingly recognized as a problem in the acquired immunodeficiency syndrome (AIDS) and may be amenable to specific treatment. Ultrasound, followed by endoscopic retrograde cholangiopancreatography (ERCP) for definitive diagnosis, is currently the prime mode of investigation of suspected hepatobiliary diseases in AIDS. There are few published reports of the use of radionuclide cholescintigraphy in the assessment of these patients. This report presents Tc-99m DISIDA cholescintigraphy data from three patients with AIDS-related hepatobiliary disease confirmed by ERCP. Radionuclide cholescintigraphy was abnormal in all three patients. In two of the subjects, there was focal duct dilation with strictures in the biliary tree. The third patient demonstrated diffuse hepatic parenchymal retention with marked delay in tracer washout. Two of the subjects, treated with specific anticryptosporidial therapy, subsequently underwent progress cholescintigraphy. In one of these patients with initial diffuse parenchymal retention, there was marked improvement in scan appearances. The second patient with initial duct dilation had no significant change in scan appearances, but quantitative analysis did demonstrate improvement in hepatobiliary tracer clearance rate. In conclusion, although ERCP remains the gold standard in the diagnosis of AIDS-related biliary disease, radionuclide cholescintigraphy may be a useful modality in these patients as a screening test before proceeding to more expensive and invasive techniques. In addition, quantitative analysis of cholescintigraphy may allow assessment of patient response to specific antimicrobial or surgical intervention.

Increased expression of interferon-gamma in hyperplastic lymph nodes from HIV-infected patients

Polyclonal B cell activation is characteristic of HIV infection and occurs in the presence of severe CD4+ lymphocyte depletion. In contrast, CD4+ lymphocytes are the dominant T cell in the reactive lymphoid tissues of patients not infected with HIV. In this study, lymph node biopsies from eight HIV-infected patients with persistent generalized lymphadenopathy syndrome (PGL) were assessed for IL-1 beta, IL-2, IL-4, IL-6, IL-10, interferon-gamma (IFN-gamma) and tumour necrosis factor-beta (TNF-beta) gene expression using the polymerase chain reaction (PCR). The cytokine gene expression of two cases of reactive adenopathy in patients not infected with HIV was assessed for comparison. IFN-gamma was expressed much more strongly in the PGL samples than in control reactive lymphoid tissues, whereas the other cytokines were expressed to a similar extent in both types of tissues. IFN-gamma may have an important role in maintaining the adenopathy of HIV-infected patients. Expression of cytokines such as IL-2, IL-4 and IL-10 in HIV nodes may be adequate to allow the recruitment of naive B cells to the reactive process.

Breast-feeding during primary maternal human immunodeficiency virus infection and risk of transmission from mother to infant

Examination of breast-fed infants of the complete cohort of Australian women whose primary human immunodeficiency virus (HIV) infection occurred postpartum allows for an estimate of risk of transmission of HIV. Ten women with no other risk factors were infected via blood transfusion postpartum. They breast-fed for up to 9 months; 2 of their infants were infected. Another woman, who shared needles for intravenous drug use, seroconverted 6-10 months post-partum. She breast-fed for 14 months. Retrovirus was visualized in the cellular and cell-free fraction of her milk by electron microscopy. Infection in her infant was confirmed at 12 months. Thus, 3 of the 11 babies at risk became infected, providing an estimate of risk of 27% for breast-feeding during primary maternal infection (95% confidence interval, 6-61%). These data establish the association of primary maternal HIV infection and breast-feeding with a high risk of transmission to infants.

Subtypes of Epstein-Barr virus (EBV) in Hodgkin's disease: association between B-type EBV and immunocompromise

Epstein-Barr virus (EBV) has been associated with Hodgkin's disease (HD) in up to 50% of cases, but the subtype of EBV involved has only recently been studied. In this report, biopsy samples from 30 patients with HD were assessed for EBV sequences using both the polymerase chain reaction (PCR) and in situ hybridization (ISH). EBV sequences were localized to the malignant Reed-Sternberg cells and their mononuclear variants (Hodgkin's cells) in 9 of the 30 cases, with 7 demonstrating A-type and 2 B-type EBV sequences. Both of the patients with B-type EBV-associated HD had features to suggest pre-existing immune compromise: one was infected with human immunodeficiency virus (HIV) and had severe CD4+ T-lymphocyte depletion; the other was a debilitated elderly patient with dementia. A previous study suggested that A-type EBV alone is associated with HD and the finding of predominantly A-type EBV in the present series is in keeping with this report. The presence of B-type EBV in the HD of patients with pre-existing immunodeficiency, taken together with the recent report that B-type EBV occurs in HIV-associated non-Hodgkin's lymphoma, suggests that B-type EBV may be an important human pathogen in immunocompromised patients.

Changes in epithelial lining fluid albumin associated with smoking and interstitial lung disease

Albumin is an important plasma protein which is useful in the assessment of in vivo membrane permeability in the lung. In subjects with interstitial lung disease (ILD) the relationship between albumin recovered from bronchoalveolar lavage (BAL) and other markers of inflammatory activity may provide useful information of the pathogenesis of the disease process. Unfortunately, its measurement is hampered by the variable dilution in BAL fluid. In this study, urea was used as a marker of epithelial lining fluid (ELF) dilution allowing the calculation of an apparent epithelial lining fluid volume and adjusted albumin content. We examined the relationship between ELF albumin content and BAL cell counts, immunoglobulin content, respiratory function tests and gallium lung scans in both smokers and nonsmokers with and without interstitial lung disease. Forty seven subjects with connective tissue disease and interstitial lung disease and 51 subjects with either connective tissue disease but no pulmonary involvement or non pulmonary malignancy (18 current smokers) underwent BAL, gallium lung scans and respiratory function tests. The subjects with ILD were further subdivided into those with active ILD or bronchiolitis using cluster analysis. In smokers without ILD an increased ELF volume and a decrease in ELF albumin were found. Increased ELF albumin was related to increased age. In subjects with ILD, increased albumin was strongly correlated with increased BAL lymphocyte absolute and differential counts, which overwhelmed any age or smoking effect. These findings suggest a possible causal relationship between lung vascular permeability and lymphocyte numbers in subjects with interstitial lung disease and reinforce the need to consider smoking and age as confounding factors in BAL analysis.

Efficacy and safety of rechallenge with low-dose trimethoprim-sulphamethoxazole in previously hypersensitive HIV-infected patients

OBJECTIVE

This study was undertaken to determine whether patients infected with HIV and with prior hypersensitivity to trimethoprim-sulphamethoxazole (TMP-SMX) can be rechallenged successfully with TMP-SMX, what factors predict successful rechallenge, and whether hypersensitivity is due to TMP or to SMX.

DESIGN

A prospective, open study.

SETTING

A tertiary referral hospital.

PATIENT

Thirty-one HIV-infected patients with a history of non-life-threatening hypersensitivity to TMP-SMX.

INTERVENTIONS

Patients received TMP (300 mg twice a week) for 2 weeks and, where no major reaction occurred, subsequently with TMP-SMX (160 and 800 mg per tablet, one tablet two times a day, twice a week). Patients who developed significant and persistent hypersensitivity ceased SMX and were subsequently challenged with TMP-dapsone (300 and 100 mg, respectively, twice a week).

MAIN OUTCOME MEASURES

That rechallenge is more likely to be successful in those with advanced HIV disease.

RESULTS

Five out of 31 (16%) patients developed hypersensitivity to TMP, and two ceased TMP as a result. Fifteen of the 26 (58%) patients who received subsequent TMP-SMX developed hypersensitivity, 12 of whom ceased TMP-SMX because of this reaction. Hypersensitivity to TMP-SMX was significantly less common in those with a CD4+ cell count < 20 x 10(6)/l than in those with a CD4+ cell count > 20 x 10(6)/l (31 versus 85%; P = 0.03). Hypersensitivity to TMP-dapsone occurred in two out of nine patients with hypersensitivity to TMP-SMX on rechallenge. One patient developed transient dyspnoea following a dose of SMX, but no other serious adverse drug reaction occurred.

CONCLUSIONS

Rechallenge with TMP-SMX appears safe in HIV-infected patients with a history of non-life-threatening hypersensitivity and is most likely to be successful in patients with a low CD4+ lymphocyte count. The data suggest a low rate cross-hypersensitivity between SMX and dapsone, at least at the doses used.