Profiling T cell activation using single-molecule fluorescence in situ hybridization and flow cytometry

Flow cytometric characterization of Ag-specific T cells typically relies on detection of protein analytes. Shifting the analysis to detection of RNA would provide several significant advantages, which we illustrate by developing a new host immunity-based platform for detection of infections. Cytokine mRNAs synthesized in response to ex vivo stimulation with pathogen-specific Ags are detected in T cells with single-molecule fluorescence in situ hybridization followed by flow cytometry. Background from pre-existing in vivo analytes is lower for RNAs than for proteins, allowing greater sensitivity for detection of low-frequency cells. Moreover, mRNA analysis reveals kinetic differences in cytokine expression that are not apparent at the protein level but provide novel insights into gene expression programs expected to define different T cell subsets. The utility of probing immunological memory of infections is demonstrated by detecting T cells that recognize mycobacterial and viral Ags in donors exposed to the respective pathogens.

Workplace contact investigations in the United States

SETTING

Five state tuberculosis (TB) control programs in the United States.

OBJECTIVES

To determine the prevalence of and treatment for latent TB infection (LTBI) among contacts of active TB cases identified in the workplace, and to describe TB control program policies for the initiation and conduct of workplace investigations.

DESIGN

Retrospective review of health department records for all culture-positive pulmonary tuberculosis cases aged > or = 15 years reported in 1996, and their contacts.

RESULTS

There were 349 cases of active TB, of whom 134 (38%) were employed. Workplace contact investigations were conducted for 42 cases, resulting in the identification of 724 contacts. The rate of LTBI was 29% overall, varying by worksite from a low of 16% to a high of 51%. LTBI estimates were higher for fully-screened contacts of smear-positive rather than of smear-negative index cases. However, fully-screened contacts of index patients with cavitary disease had lower LTBI estimates than those of index patients without cavitation. Treatment for LTBI was initiated in 45% of infected contacts. The five programs had somewhat variable policies regarding workplace contact investigations. Data on HIV co-infection and place of birth of contacts were largely missing.

CONCLUSION

Factors contributing to LTBI among workplace contacts may include the presence of persons with pre-existing LTBI or a positive skin test as a result of BCG vaccination, clinical characteristics of the index case, and workplace environmental characteristics conducive to transmission. Standard guidelines for workplace investigations, written workplace investigation policies, and standard data collection practices are needed to better apportion the causes of observed infection rates in the workplace.

Rethinking the socioeconomics and geography of tuberculosis among foreign-born residents of New Jersey, 1994-1999

OBJECTIVES

This study investigated the socioeconomic profile of foreign-born tuberculosis patients in New Jersey.

METHODS

Foreign- and US-born tuberculosis patients in 1994-1999 were compared using various measures of socioeconomic status.

RESULTS

Out of 4295 tuberculosis patients, 2005 (47%) were foreign-born. Foreign-born patients resided in more affluent, more educated, and less crowded areas than did US-born patients (P <.005). They were also more likely to have been employed during the 2 years before diagnosis (62% vs 41%, P <.001). Private physicians treated the majority of South Asian-born patients.

CONCLUSIONS

Substantial numbers of employed foreign-born tuberculosis patients now reside in affluent New Jersey locations. Changes in tuberculosis control programs may be required when the socioeconomic status and place of residence of foreign-born populations diverge from traditional assumptions linking poverty with tuberculosis.

Evaluation of investigations conducted to detect and prevent transmission of tuberculosis

CONTEXT

Contact investigations are routinely conducted by health departments throughout the United States for all cases of active pulmonary tuberculosis (TB) to identify secondary cases of active TB and latent TB infection and to initiate therapy as needed in these contacts. Little is known about the actual procedures followed, or the results.

OBJECTIVES

To evaluate contact investigations conducted by US health departments and the outcomes of these investigations.

DESIGN, SETTING, AND SUBJECTS

Review of health department records for all contacts of 349 patients with culture-positive pulmonary TB aged 15 years or older reported from 5 study areas in the United States during 1996.

MAIN OUTCOME MEASURES

Number of contacts identified, fully screened, and infected per TB patient; rates of TB infection and disease among contacts of TB patients; and type and completeness of data collected during contact investigations.

RESULTS

A total of 3824 contacts were identified for 349 patients with active pulmonary TB. Of the TB patients, 45 (13%) had no contacts identified. Of the contacts, 55% completed screening, 27% had an initial but no postexposure tuberculin skin test, 12% were not screened, and 6% had a history of prior TB or prior positive tuberculin skin test. Of 2095 contacts who completed screening, 68% had negative skin test results, 24% had initial positive results with no prior test result available, 7% had documented skin test conversions, and 1% had active TB at the time of investigation. Close contacts younger than 15 years (76% screened vs 65% for older age groups; P<.001) or exposed to a TB patient with a positive smear (74% screened vs 59% for those with a negative smear; P<.001) were more likely to be fully screened. Close contacts exposed to TB patients with both a positive smear and a cavitary chest radiograph were more likely to have TB infection or disease (62% vs 33% for positive smear only vs 44% for cavitary radiograph only vs 37% for neither characteristic; P<.001). A number of factors associated with TB patient infectiousness, contact susceptibility to infection, contact risk of progression to active TB, and amount of contact exposure to the TB patient were not routinely recorded in health department records.

CONCLUSIONS

Improvement is needed in the complex, multistep process of contact investigations to ensure that contacts of patients with active pulmonary TB are identified and appropriately screened.

Mycobacterium tuberculosis miniepidemic in a church gospel choir

BACKGROUND

Conventional contact investigation and molecular fingerprinting of Mycobacterium tuberculosis isolates in tuberculosis (TB) outbreaks have facilitated recognition as well as application of public health control activities. Singing in a choir as an activity that promotes TB transmission has been occasionally recognized. Such avocational transmission in a middle class community can occur with attendant difficulties encountered in contact investigation.

METHODS

Five cases of TB (one index case; three secondary cases; one unassociated case) were identified among members of a famous church gospel choir in Newark, NJ. DNA fingerprinting and susceptibility testing were done on all retrieved strains. Of 306 choir members who had tuberculin tests, 19% were reactors. The presumed outbreak site was investigated.

RESULTS

Four of the five patients were tenors, and one was an alto. Tenors were approximately twice as likely to be tuberculin reactors than subjects with other vocal ranges combined (relative risk, 2.04; 95% confidence interval, 1.17 to 3.56). An air ventilation outlet was directly in front of the tenor section. Some limited extra-church activity between choir members may have contributed to transmission.

CONCLUSION

Conventional contact investigation must be supplemented by newer techniques, such as DNA fingerprinting, in identifying possible outbreak transmission. Singing, location of a ventilation outlet, and exposure time may have contributed to TB transmission in this outbreak. Transmission need not only be in congregate settings among well-defined socioeconomic groups but may occur unexpectedly in middle class communities.

An incentive in tuberculosis preventive therapy for an inner city population

SETTING

Measures known to improve adherence such as short course chemoprophylaxis and directly observed therapy can be enhanced to a significant extent/by the use of incentives. Adherence to tuberculosis therapy is influenced by several factors, including the health care system, complexity of therapeutic regimens and patient's characteristics. Individual factors that negatively influence patient's adherence are the most difficult to counter. Preventive tuberculosis therapy is doubly challenging because the benefit of treatment is not felt, while toxicity from the medication, when it occurs, is experienced immediately. Ingenious incentives therefore have to make it worth the patient's while. During a study on preventive regimens, a request for an incentive, Sustacal, was observed to help completion of preventive regimens. Components of individual TB programs may help in patient adherence; it is important for health care staff to identify these aspects and, if they are successful, utilize these as an incentive to complete treatment.

Management after exposure to tuberculosis

The increased incidence of tuberculosis-coupled with the emergence of mycobacterial strains resistant to the most effective drugs-has highlighted the importance of identifying transmission and preventing active disease. Skin test conversion can document infection, except in most patients vaccinated with bacille Calmette-Guérin. Prophylactic medication is effective, but not without complications.

Incidence of tuberculosis in the United States among HIV-infected persons. The Pulmonary Complications of HIV Infection Study Group

BACKGROUND

The resurgence of tuberculosis in the United States is largely linked to the human immunodeficiency virus (HIV) epidemic. Despite this link, the epidemiology of tuberculosis and preventive strategies in patients infected with HIV are not completely understood.

OBJECTIVES

To determine the incidence and predictors of tuberculosis in HIV-infected persons.

DESIGN

Prospective, multicenter cohort study.

SETTING

Community-based cohort of persons with and without HIV infection at centers in the eastern, midwestern, and western United States.

PARTICIPANTS

1130 HIV-seropositive patients without AIDS who were followed for a median of 53 months (814 homosexual men, 261 injection drug users, and 55 women who had acquired HIV through heterosexual contact).

MEASUREMENTS

Delayed hypersensitivity response to purified protein derivative (PPD) tuberculin and mumps antigen, CD4 T-lymphocyte counts, and frequency of tuberculosis.

RESULTS

31 HIV-seropositive patients developed tuberculosis (0.7 cases per 100 person-years [95% CI, 0.5 to 1.0]). The most important demographic risk factor was location (adjusted risk ratio for eastern compared with midwestern and western United States, 4.1 [CI, 2.0 to 8.4]). Tuberculosis occurred more frequently in persons with CD4 counts of less than 200 cells/mm3 (1.2 cases per 100 person-years [CI, 0.7 to 1.9]) than in those with higher counts (0.5 cases per 100 person-years [CI, 0.3 to 0.8]). The rate of tuberculosis was highest among tuberculin converters (5.4 cases per 100 person-years [CI, 1.1 to 15.7]), lower among patients who were PPD positive at first testing (4.5 cases per 100 person-years [CI, 1.6 to 9.7]), and lowest among patients who remained PPD negative (0.4 cases per 100 person-years [CI, 0.2 to 0.7]). Tuberculosis was not reported among persons who had PPD reactions of 1 to 4 mm. Compared with that of patients who tested positive for mumps, the risk for tuberculosis of those who tested negative was increased about sevenfold if they were PPD positive (P < 0.03) and fourfold if they were PPD negative (P < 0.02).

CONCLUSIONS

Incidence of tuberculosis was higher in the eastern United States, in patients with CD4 counts of less than 200 cells/mm3, and in PPD-positive patients. Analysis of tuberculin reaction size supports the current interpretive criteria of the Centers for Disease Control and Prevention. Nonreactivity to mumps antigen indicated increased risk for tuberculosis independent of PPD response.

Respiratory disease trends in the Pulmonary Complications of HIV Infection Study cohort. Pulmonary Complications of HIV Infection Study Group

We examined trends in the incidence of specific respiratory disorders in a multicenter cohort with progressive human immunodeficiency virus (HIV) disease during a 5-yr period. Individuals with a wide range of HIV disease severity belonging to three transmission categories were evaluated at regular intervals and for episodic respiratory symptoms using standard diagnostic algorithms. Yearly incidence rates of respiratory diagnoses were assessed in the cohort as a whole and according to CD4 count or HIV transmission category. The most frequent respiratory disorders were upper respiratory tract infections, but the incidence of lower respiratory tract infections increased as CD4 counts declined. Specific lower respiratory infections followed distinctive patterns according to study-entry CD4 count and transmission category. Acute bronchitis was the predominant lower respiratory infection of cohort members with entry CD4 counts > or = 200 cells/mm3. In cohort members with entry CD4 counts of 200 to 499 cells/mm3, the incidence of bacterial and Pneumocystis carinii pneumonia each increased an average of 40% per year. In members with entry CD4 counts < 200 cells/mm3, acute bronchitis, bacterial pneumonia, and P. carinii pneumonia occurred at high rates without discernible time trends, despite chemoprophylaxis in more than 80% after Year 1, and the rate of other pulmonary opportunistic infections increased over time. Each year, injecting drug users had a higher incidence of bacterial pneumonia than did homosexual men. The yearly rate of tuberculosis was < 3 episodes/100 person-yr in each entry CD4 and HIV-transmission group. We conclude that the time trends of HIV-associated respiratory disorders are determined by HIV disease stage and influenced by transmission category. Whereas acute bronchitis is prevalent during all stages of HIV infection, incidence rates of bacterial pneumonia and P. carinii pneumonia rise continuously during progression to advanced disease. In advanced disease, the incidence of acute bronchitis, bacterial pneumonia and P. carinii pneumonia is high despite widespread chemoprophylaxis.

Bacterial pneumonia in persons infected with the human immunodeficiency virus. Pulmonary Complications of HIV Infection Study Group

BACKGROUND

Patients with human immunodeficiency virus (HIV) infection are at increased risk for bacterial pneumonia in addition to opportunistic infection. However, the risk factors for bacterial pneumonia and its incidence in this population are not well defined.

METHODS

In a multicenter, prospective, observational study, we monitored 1130 HIV-positive and 167 HIV-negative participating adults for up to 64 months for pulmonary disease. The HIV-positive group comprised 814 homosexual or bisexual men, 261 injection-drug users, and 55 female partners of HIV-infected men.

RESULTS

There were 237 episodes of bacterial pneumonia among the HIV-positive participants (rate, 5.5 per 100 person-years), as compared with 6 episodes among the HIV-negative participants (rate, 0.9 per 100 person-years; P < 0.001). The rate of bacterial pneumonia increased with decreasing CD4 lymphocyte counts (2.3, 6.8, and 10.8 episodes per 100 person-years in the strata with more than 500, 200 to 500, and fewer than 200 cells per cubic millimeter, respectively; P < or = 0.022 for each comparison). Injection-drug users had a higher rate of bacterial pneumonia than did homosexual or bisexual men or female partners. In the stratum with the fewest CD4 lymphocytes, cigarette smoking was associated with an increased rate of pneumonia. Mortality was almost four times higher among participants with an episode of pneumonia than among the others. Prophylaxis with trimethoprim-sulfamethoxazole was associated with a 67 percent reduction in confirmed episodes of bacterial pneumonia (P = 0.007).

CONCLUSIONS

Bacterial pneumonia is more frequent in HIV-positive persons than in seronegative controls, and the risk is highest among those with CD4 lymphocyte counts below 200 per cubic millimeter and among injection-drug users.

Tuberculin and anergy testing in HIV-seropositive and HIV-seronegative persons. Pulmonary Complications of HIV Infection Study Group

OBJECTIVE

To determine the prevalence and predictors of reactivity to tuberculin purified protein derivative (PPD) and skin test anergy in patients with human immunodeficiency virus (HIV) infection and in HIV-seronegative controls.

DESIGN

Cross-sectional analysis of baseline data from a prospective, multicenter study of pulmonary complications of HIV infection.

SETTING

Community-based cohort of persons with and without HIV infection.

PATIENTS

A total of 1171 HIV-seropositive patients without AIDS (841 homosexual men, 274 intravenous drug users, and 56 women with heterosexually acquired infection); 182 HIV-seronegative persons (125 homosexual men and 57 intravenous drug users).

MEASUREMENTS

Delayed-type hypersensitivity response to tuberculin PPD, trichophytin, mumps, and Candida antigens; T-lymphocyte subsets.

RESULTS

The prevalence of tuberculin PPD reactivity was higher among intravenous drug users than among homosexual men, in both HIV-seronegative (19.1% compared with 6.8%, P = 0.03) and HIV-seropositive persons (15.1% compared with 2.5%, P < 0.001). Among HIV-infected patients, the prevalence of tuberculin reactivity varied directly and that of anergy inversely with the absolute CD4 lymphocyte count. Prevalences were 1% and 72%, respectively, in patients with fewer than 200 CD4 cells/mm3, and 8.4% and 25.5%, respectively, in those with 600 CD4 cells/mm3 (P < 0.001 for both comparisons). Patients with HIV infection and fewer than 400 CD4 lymphocytes/mm3 had a lower prevalence of PPD reactivity than HIV-seronegative controls (2.7% compared with 10.0%, P < 0.001). The strongest predictors of tuberculin reactivity were intravenous drug use, black race, a previous positive PPD test result, and a history of Calmette-Guérin bacillus vaccination. The strongest predictor of anergy was HIV seropositivity.

CONCLUSIONS

The response to delayed-type hypersensitivity antigens depends on immune status. The value of PPD and anergy testing in HIV-seropositive patients depends on the ability of such testing to predict subsequent tuberculosis, which is imprecisely known. Until more data or better methods are available, these tests should be done as early as possible in the course of HIV infection.

Tuberculosis and the atypical pneumonia syndrome

Literature over the last 30 years has warned of the atypical or unusual characteristics of pulmonary TB. Shifts in the demographic distribution of the disease in the US are ascribed in part to the occurrence of HIV disease outbreaks in group settings, and to recent influxes of immigrants from developing countries. Unsuspected pulmonary TB is particularly common among the elderly. Socioeconomic categories not traditionally thought of as being high risk also are affected. In the low-risk setting, TB can be treacherous because misdiagnosis is likely. Tuberculosis is a great mimicker, and it can appear to be any acute community-acquired pneumonia such as atypical pneumonia. Symptoms and signs are few. A high index of awareness is therefore essential. The approach to atypical pneumonia emphasizes the need to include TB in the differential diagnosis to be aware of the total disease spectrum of TB and understand the risk factors. The atypical pneumonia syndrome is only a portion of the clinical spectrum of TB.

Rib cage and abdominal volume displacements during breathing in pregnancy

To examine the effect of abdominal distension upon the actions of both rib cage and abdomen, we made serial determinations of tidal volume with a chest wall volume-displacement method in 8 pregnant women. Enhancement of tidal volume, long recognized in pregnancy, was achieved usually by augmentation of rib cage volume displacement. By contrast, abdominal volume displacement during quiet breathing is not altered in a predictable fashion by the gravid state. Given these findings, we hypothesize that the increased diaphragmatic contraction of pregnancy is accompanied by the transmission of that force to the lower rib cage via the area of apposition and that diaphragmatic contraction accounts for enhancement of the tidal breath. Diminished abdominal compliance might contribute to the augmentation of rib cage volume displacement as well. Konno-Mead diagrams suggest that this hypothesis is true in some, but not all, subjects.

Bioavailability of a once daily-administered theophylline preparation. A comparison study

To evaluate the bioavailability of a new theophylline preparation suitable for once-a-day (od) oral administration, we performed a nonrandomized crossover study in which the absorption of the OD and a standard twice-a-day (bid) preparation were compared. Eight stable asthmatic patients, after having achieved steady-state, received an average of 975 mg of OD preparation at 8 PM. The protocol was later repeated with the same subjects receiving 487.5 mg of the bid preparation at 8 PM and again at 8 AM using the same total dose. The maximal mean serum concentrations were 15.5 +/- 1.6 (SEM) micrograms/ml for the od preparation on the 8th hour and 12.7 +/- 2.2 for the bid regimen. The trough level was 7.4 +/- 1.2 micrograms/ml for the od regimen and 10.6 +/- 1.6 for the bid regimen. With either regimen, therapeutic theophylline levels could be observed throughout the 24-hour study period. Anhydrous theophylline may be administered as a single daily dose agent.

Respiratory mechanical effects of abdominal distension

We develop a theory to predict the partitioning of a change in volume of the abdominal contents into the end-expiratory volume changes of the lung, rib cage, and anterior abdominal wall. First, we calculate the distribution of such a volume change using the relative compliances of the three compartments. We then consider the inspiratory influence of abdominal pressure on the rib cage and its effect on the distribution of this volume. We test our theory by inducing gastric distension in three experienced laboratory personnel. We instilled and subsequently withdrew 1 liter of water from a gastric balloon and examined the effects of this change in gastric volume on the relaxation characteristics of the respiratory system. The distribution of the volume change that would be expected from the observed relative compliances of the three compartments would be approximately 66% into change in lung volume, 25% into change in rib cage volume, and 9% into change in abdominal volume. Instead, in line with our predictions for acute gastric distension, approximately 33% went into decrease in lung volume, 40% into increase in rib cage volume, and 26% into increase in abdominal volume. These results suggest that the interactions among the rib cage, abdomen, and diaphragm are such as to defend against large changes in end-expiratory lung volume in the face of abdominal distension.

Minute ventilation in asthma. Enhancement by mouthpiece and depression by oxygen administration

To evaluate independently the effects of an inspiratory stimulus (a mouthpiece) and a ventilatory depressant (oxygen) on minute ventilation (VE) in asthma, we measured VE with magnetometers in 18 asthmatic subjects. When room air was inspired from a loose-fitting mask, VE was 10.2 +/- 0.6 L/min. When oxygen was substituted for room air, VE decreased (8.4 +/- 0.6). In contrast, when oxygen was given by mouthpiece, VE increased (12.9 +/- 0.7). We conclude that in the clinical setting, the mouthpiece artifact may operate either to exaggerate the tidal breath or to obscure the effect of a respiratory depressant (e.g., oxygen) upon the measurement of resting ventilation.