[Dynamic analysis of tuberculosis specific mononuclear cells in peripheral blood of HIV patients with tuberculosis]

Objective: To evaluate the response of peripheral blood mononuclear cells (PBMCs) in patients with human immunodeficiency virus (HIV) combined with active tuberculosis (TB) to TB-specific antigen stimulation. Methods: From January to December, 2018, individuals infected with both HIV and TB (HIV/TB group) were taken as the study subjects. Individuals infected with HIV alone (HIV group), individuals infected with TB alone (TB group) and healthy people (Health control group, HC group) were taken as the control groups. PBMCs were isolated and stimulated with purified protein derivative of bacillus calmette-guerin (BCG-PPD). The expression of surface molecules in T cells (CD3⁺, CD4⁺, CD8⁺) and monocytes (CD14⁺) and the percentages of Interferon (IFN)-γ and tumor necrosis factor (TNF)-α were detected by cell surface molecular staining, direct intracellular cytokine staining and flow cytometry (CD3^- lymphocytes were mainly B lymphocytes and NK cells). Analysis of non-parametric data was used to compare the data between the two groups, and paired t-test was used to compare the data before and after PPD stimulation in each group. Results: Before PPD stimulation, the percentage of IFN-γ⁺ CD8⁺ cells in the peripheral blood of HIV/TB group(mean 0.52%) was significantly lower than that in TB group(mean 0.94%, P=0.010). The TNF-α⁺cell percentages in CD3⁺, CD4⁺, CD8⁺, or CD14⁺ cells in the HIV/TB group(mean 19.2%) were significantly lower than those in the HIV group(mean 31.9%, P=0.002). The percentage of TNF-α secreted by monocytes in the HIV group was significantly lower than that in the HC group. The percentages of IFN-γ⁺ CD8⁺ and IFN-γ⁺ CD3^- cells in the peripheral blood of the TB group (mean 0.94%) were significantly higher than thoset in the HC group(mean 0.51%, P=0.020), while the percentages of TNF-α⁺ cells in each subsets of PBMCs were significantly lower than those in the HC group. After PPD stimulation, the percentage of IFN-γ⁺ CD8⁺ cells in the HIV/TB group was significantly lower than that in the TB group(P=0.008), and the change was more marked than that before stimulation. The percentage of IFN-γ⁺ CD8⁺ cells in the HIV group(mean 0.20%) was lower than that in the HC group (mean 0.52%, P=0.044). The percentage of IFN-γ⁺ CD3^- in the TB group was significantly higher than in the HC group. There were no significant differences in TNF-α⁺ cell percentages in the 3 groups compared with the control group after PPD stimulation. The percentages of IFN-γ⁺ CD4⁺ cells in the HC and the TB groups were significantly increased after PPD stimulation in each group (P=0.002, P=0.001, respectively). However, there were no significant differences of IFN-γ⁺ CD4⁺ cell percentages in the HIV/TB group and the HIV group. The percentages of TNF-α production by monocytes were significantly increased after PPD stimulation in all groups. Conclusions: Chronic Mycobacterium tuberculosis (MTB) infection reduced the ability of PBMCs to produce TNF-α. For patients with TB infection, the production of TNF-α was reduced when combined with HIV infection. The capacity of CD8⁺ and CD3^- lymphocytes to produce IFN-γ was increased in TB patients, while the capacity of CD8⁺ T cells to produce IFN-γ was decreased with co-infection of HIV. Infection of HIV weakened the immune response to MTB infection, which made the clinical diagnosis and treatment of TB more difficult.

Persistent expression of activation markers on Mycobacterium tuberculosis-specific CD4 T cells in smear negative TB patients

Background

T cell activation (HLA-DR, CD-38), proliferation (KI-67), and functional (IFN-γ, TNF-α) markers have recently been shown to be useful in predicting and monitoring anti-TB responses in smear positive TB, but previous research did not characterize the activation and proliferation profiles after therapy of smear negative TB.

Methodology

In this study, we used polychromatic flow cytometry to assess selected PPD-specific T cell markers using fresh PBMC of smear negative and positive pulmonary tuberculosis (PTB) patients, recruited from health facilities in Addis Ababa.

Result

Levels of activation (HLA-DR, CD38) and proliferation (Ki-67) among total unstimulated CD4 T cells decreased significantly after therapy, particularly at month 6. Similarly, levels of PPD-specific T cell activation markers (HLA-DR, CD-38) were significantly lower in smear positive PTB patients following treatment, whereas a consistent decline in these markers was less apparent among smear negative PTB patients at the sixth month.

Conclusion

After six months of standard anti-TB therapy, persistent levels of activation of HLA-DR and CD-38 from PPD specific CD4+T cells in this study could indicate that those markers have little value in monitoring and predicting anti-TB treatment response in smear negative pulmonary TB patients in Ethiopian context.

The variable prevalence of bovine tuberculosis among dairy herds in Central Ethiopia provides opportunities for targeted intervention

Bovine tuberculosis (bTB) is an important disease for dairy productivity, as well as having the potential for zoonotic transmission. Previous prevalence studies of bTB in the dairy sector in central Ethiopia have suggested high prevalence, however, they have been limited to relatively small scale surveys, raising concerns about their representativeness. Here we carried out a cross sectional one-stage cluster sampling survey taking the dairy herd as a cluster to estimate the prevalence of bTB in dairy farms in six areas of central Ethiopia. The survey, which to date is by far the largest in the area in terms of the number of dairy farms, study areas and risk factors explored, took place from March 2016 to May 2017. This study combined tuberculin skin testing and the collection of additional herd and animal level data by questionnaire to identify potential risk factors contributing to bTB transmission. We applied the single intradermal cervical comparative tuberculin (SICCT) test using >4mm cut-off for considering an individual animal as positive for bTB; at least one reactor animal was required for a herd to be considered bTB positive. Two hundred ninety-nine dairy herds in the six study areas were randomly selected, from which 5,675 cattle were tested. The overall prevalence of bTB after standardisation for herd-size in the population was 54.4% (95% CI 48.7–60%) at the herd level, and it was 24.5% (95% CI 23.3–25.8) at the individual animal level. A Generalized Linear Mixed Model (GLMM) with herd and area as random effect was used to explore risk factors association with bTB status. We found that herd size, age, bTB history at farm, and breed were significant risk factors for animals to be SICCT positive. Animals from large herds had 8.3 times the odds of being tuberculin reactor (OR: 8.3, p-value:0.008) as compared to animals from small herds. The effect of age was strongest for animals 8–10 years of age (the oldest category) having 8.9 times the odds of being tuberculin reactors (OR: 8.9, p-value:<0.001) compared to the youngest category. The other identified significant risk factors were bTB history at farm (OR: 5.2, p-value:0.003) and cattle breed (OR: 2.5, p-value: 0.032). Our study demonstrates a high prevalence of bTB in central Ethiopia but with a large variation in within-herd prevalence between herds, findings that lays an important foundation for the future development of control strategies.

Description of pediatric tuberculosis evaluated in a referral center in istanbul Turkey

PURPOSE

Diagnosis of tuberculosis (TB) in children is more challenging than in adults. This study aimed to describe demographical, clinical and laboratory findings of children diagnosed with tuberculosis in Turkey, including the issues of contact tracing, culture positivity and forms of the disease.

MATERIALS AND METHODS

Clinical and laboratory data of 51 children with a mean age of 8.0±4.6 years who were diagnosed with TB were retrospectively reviewed. Main diagnostic tools included tuberculin skin test, chest X-ray, sputum/gastric aspirate culture with sensitivity testing, and direct microscopy for acid-fast bacilli on available samples. Clinical characteristics and outcomes of the patients were examined.

RESULTS

Thirty-six (70.6%) children were diagnosed with intra-thoracic and 15 (29.4%) with extra-thoracic tuberculosis. Twenty-eight of the patients had a positive Bacillus Calmette-Guérin vaccine scar (28/51, 54.9%) and 23/51 (45.1%) had a positive tuberculin skin test. An adult TB contact was identified in 27 (52.9%) of the cases. On direct microscopy, acid-fast bacilli were found in nine (17.6%) patients and positive culture for Mycobacterium tuberculosis was found in 19 (37.3%). Drug resistance to isoniazid was detected in four (7.8%). One patient with nephrotic syndrome and miliary tuberculosis died during follow-up. All other patients responded well to the treatment.

CONCLUSION

Focusing on active contact tracing among all household contacts of tuberculous cases may be helpful in early identification and controlling childhood disease, even in regions with low disease prevalence. Adopting a suspicious and proactive approach in this particular age group is warranted.

Progesterone prevents allodynia after experimental spinal cord injury

Chronic pain after spinal cord injury represents a therapeutic challenge. Progesterone, a neuroprotective steroid, has been shown to modulate nociceptive thresholds, whereas its effect on neuropathic pain needs to be further explored. In this study, we evaluated whether progesterone could ameliorate pain-associated behaviors in animals subjected to a spinal cord hemisection. The development of mechanical and cold allodynia was assessed in injured male rats treated with daily injections of progesterone or vehicle. The expression of N-methyl-D-aspartate receptor (NMDAR) subunits, protein kinase C gamma (PKCγ), preprodynorphin (ppD), and kappa opioid receptor (KOR), key players in chronic pain mechanisms, was determined in the dorsal spinal cord. Twenty-eight days after injury, all vehicle-treated animals presented allodynic behaviors and a marked increase in NMDAR subunits, PKCγ, and ppD mRNA levels, with no changes in KOR mRNA levels. Progesterone prevented the development of mechanical allodynia and reduced the painful responses to cold stimulation. In correlation with the attenuation of pain behaviors, the steroid prevented NMDAR subunits and PKCγ mRNAs upregulation, did not modify the elevated ppD mRNA levels, but increased KOR expression. In conclusion, progesterone modulates neuropathic pain after spinal cord injury, creating a favorable molecular environment that may decrease spinal nociceptive signaling.

PERSPECTIVE

The present study suggests that progesterone administration could represent an interesting strategy to modulate neuropathic pain circuits after spinal cord injury. Further studies are needed to investigate the potential progesterone receptors involved in these actions.

Potential role for IL-2 ELISpot in differentiating recent and remote infection in tuberculosis contact tracing

Interferon (IFN)-gamma release assays (IGRA) have improved tuberculosis contact tracing, but discrimination of recent from remote Mycobacterium tuberculosis contacts is not possible by IGRA alone. We present results of a tuberculosis contact investigation with a new early-secretory-antigenic-target (ESAT)-6 and culture-filtrate-protein (CFP)-10 specific interleukin (IL)-2 ELISpot in addition to ESAT-6 and CFP-10 specific IFN-gamma ELISpot and tuberculin skin testing (TST). Results of the TST, IFN-gamma ELISpot and IL-2 ELISpot were positive in 6/172 (3.4%), 7/167 (4.2%) and 6/196 (3.1%) of contacts, respectively. Close contact (> or =100 hours) to the index case increased the risk of positive results in the IFN-gamma ELISpot, TST, and IL-2 ELISpot by 40.8, 19.3, and 2.5 times, respectively. Individuals with a positive IFN-gamma ELISpot/negative IL-2 ELISpot result had a median (IQR) duration of index case exposure of 568 hours (133_1000) compared to individuals with a positive IFN-gamma ELISpot/positive IL-2 ELISpot result (median = 24 hours; 20_130; p-value = 0.047). Combination of a M. tuberculosis specific IFN-gamma ELISpot with a M. tuberculosis specific IL-2 ELISpot significantly improved the identification of individuals with the highest risk of recent M. tuberculosis infection and is a promising method that should be explored to target tuberculosis preventive chemotherapy.

Identification of key processes that control tumor necrosis factor availability in a tuberculosis granuloma

Tuberculosis (TB) granulomas are organized collections of immune cells comprised of macrophages, lymphocytes and other cells that form in the lung as a result of immune response to Mycobacterium tuberculosis (Mtb) infection. Formation and maintenance of granulomas are essential for control of Mtb infection and are regulated in part by a pro-inflammatory cytokine, tumor necrosis factor-α (TNF). To characterize mechanisms that control TNF availability within a TB granuloma, we developed a multi-scale two compartment partial differential equation model that describes a granuloma as a collection of immune cells forming concentric layers and includes TNF/TNF receptor binding and trafficking processes. We used the results of sensitivity analysis as a tool to identify experiments to measure critical model parameters in an artificial experimental model of a TB granuloma induced in the lungs of mice following injection of mycobacterial antigen-coated beads. Using our model, we then demonstrated that the organization of immune cells within a TB granuloma as well as TNF/TNF receptor binding and intracellular trafficking are two important factors that control TNF availability and may spatially coordinate TNF-induced immunological functions within a granuloma. Further, we showed that the neutralization power of TNF-neutralizing drugs depends on their TNF binding characteristics, including TNF binding kinetics, ability to bind to membrane-bound TNF and TNF binding stoichiometry. To further elucidate the role of TNF in the process of granuloma development, our modeling and experimental findings on TNF-associated molecular scale aspects of the granuloma can be incorporated into larger scale models describing the immune response to TB infection. Ultimately, these modeling and experimental results can help identify new strategies for TB disease control/therapy.

Tuberculosis is a common and deadly infectious disease caused by a highly successful bacterium, Mycobacterium tuberculosis (Mtb). Multiple host immune factors control the formation of a self-organizing aggregate of immune cells termed a granuloma in the lungs after inhalation of Mtb. One such factor, tumor necrosis factor-α (TNF), is a protein that regulates inflammatory immune responses. Availability of TNF within a TB granuloma has been proposed to have a critical role in the protective immunity against TB. However, direct measurement of the level of TNF in a granuloma is not experimentally feasible. Therefore, we develop a mathematical model based on an experimental model of granuloma developed in mice to predict TNF availability in a granuloma. We measure values of critical model parameters and explore mechanisms that influence TNF availability in the granuloma. We find that cellular organization in a granuloma and intracellular trafficking of TNF control TNF availability in a granuloma. Further, our model analysis also highlights anti-TNF drug properties that determine their TNF neutralization power. Our findings complement and extend those of recent studies on the role of TNF in the immune response against TB.

Immunogenicity of neonatal BCG vaccination in children entering primary school

This study has been designed to evaluate the immunogenicity of neonatal BCG-vaccination in children at the age of 7 to 8 years, by skin test using Purified Protein Derivative (PPD), as BCG vaccination at birth is a part of routine program of immunization in our country, Iran; we decided to study its efficacy and also tried to determine if there is any correlation between PPD-test results and BCG scar size. This is a comparative study on 150 children (94 males and 56 females) at the age of 7 to 8 years, who possess neonatal-BCG scar. They were chosen from several primary schools in Tabriz-Iran, by simple random sampling and tested with 0.1 mL of 5-unit-PPD solution (a product of Iran Institute of Razi); then observations recorded. The average diameter of BCG scars were 7.03 mm in girls, 5.45 mm in boys and 6.05 for all. The diameter of induration area resulted from PPD-test after 72 h was less than 5 mm in 95.33% and 5-9 mm in 4.66% of studied children; there was no case with induration area of 10 mm or more at all. Every child who developed an induration area of 5 mm or more by PPD test, had a BCG scar with the diameter of 5 mm or more. There was a statistically meaningful direct correlation between sizes of neonatal-BCG scar and diameter of induration area after PPD-test (r = 0.21 and p = 0.008). This study shows that reactivity to PPD test (and probably immunity against tuberculosis) decreases as age increases; therefore it seems to be necessary to repeat BCG-vaccination in children at the age of entering primary school.

Human natural killer T cells (NKT), NK and T cells in pulmonary tuberculosis: potential indicators for disease activity and prognosis

One third of the world's population is infected with Mycobacterium tuberculosis (MTB). However, active disease can develop only in a small percentage, when the immunity is weakened. The acquired immune response to MTB is primarily mediated by T cells. Natural killer (NK) cells play a central role in innate immunity to microbial pathogens. Human NKT cells have characteristics of both T and NK cells and also exhibit antimycobacterial activity. This work aimed to enumerate T, NK and NKT cells in active pulmonary TB compared with healthy controls and to study the correlation between these cells with different factors affecting prognosis of pulmonary TB as disease severity, complications or associated diseases, antitubrculosis chemotherapy, and age & gender. Of the 22 active tuberculosis patients examined, 17 were recent cases and 5 recurrent. Healthy controls were divided into 14 individuals with detectable reaction to purified protein derivative (PPD+) and 14 individuals without detectable reaction to PPD-. The percentages of T, NK and NKT cells in erythrocyte-lysed whole blood samples were determined using flowcytometry. The percentage of NKT cells was significantly higher among the recently diagnosed MTB cases as compared with both PPD+ (P < 0.01) and PPD- (P < 0.01) healthy controls, while no significant difference could be found in the percentages of T or NK cells among these groups. However, comparing recurrent cases with recently diagnosed cases showed a significant difference only in the percentage of T cells (P < 0.01). There was also a significant difference in the percentage of T cells according to severity of disease (P < 0.01) and in the association of diabetes mellitus (P < 0.01). Age, gender and treatment with antituberculosis chemotherapy had no effect on the percentages of T, NK or NKT cells. It is concluded that T and NKT cells play an important role in immunity against TB. In active pulmonary tuberculosis, increased T cell count points to severity of the disease, while their reduced count predicts bad prognosis. Human NKT cell count is a marker of disease activity. Enumeration of these cells in peripheral blood can be used as a non-invasive prognostic indicator for patients with active pulmonary TB.

Resident Th1-like effector memory cells in pulmonary recall responses to Mycobacterium tuberculosis

We recently described a model of Th1 recall responses based on segmental antigen challenge with purified protein derivative of Mycobacterium tuberculosis (PPD). Bronchoscopic instillation of 0.5 tuberculin units of PPD resulted in localized lymphocytic inflammation in PPD-positive subjects only. Recruited lymphocytes were predominantly CD4+ and were enriched for cells capable of PPD-specific interferon (IFN)-gamma production. In the current study, we investigated the mechanisms by which this localized recall response is mobilized. Bronchoscopic PPD challenge of skin test-positive subjects resulted in the production of CXCR3 ligands IFN-gamma-inducible protein (IP)-10 and monokine induced by IFN-gamma (Mig), but not of CCR5 ligands macrophage inflammatory protein-1alpha and regulated-upon activation, normal T-cell expressed and secreted, whereas skin test-negative subjects produced none of these chemokines. Baseline bronchoalveolar lavage (BAL) cells of skin test-positive subjects produced IP-10 and Mig in response to in vitro stimulation as well. Because IP-10 and Mig are IFN-gamma-inducible chemokines, these findings suggested that chemokine responses to PPD were facilitated by resident memory cells of the lung. Further studies confirmed that baseline BAL lymphocytes of PPD-positive subjects produce IFN-gamma in response to PPD, and that, compared with peripheral blood, BAL cells are preferentially enriched for PPD-specific lymphocytes. This IFN-gamma production is predominantly a function of CD4+ T cells that display the CD45RO+/CCR7- surface phenotype characteristic of effector memory cells.

Monocyte chemotactic protein-1 production in patients with active pulmonary tuberculosis and tuberculous pleurisy

OBJECTIVE

The role of monocyte chemotactic protein (MCP)-1 in human pulmonary and pleural tuberculosis (TB) was assessed by examining its production in clinical samples from patients with active pulmonary TB and tuberculous pleurisy (TBP).

METHODS

Serum was obtained from 26 active pulmonary TB patients [14 early TB (E-TB), and 12 chronic refractory TB (CR-TB)] and 15 healthy tuberculin reactors (HTRs). The monocytes and peripheral blood mononuclear cells (PBMCs) were separated and stimulated with purified protein derivatives (PPD) or the 30-kDa antigen of Mycobacterium tuberculosis. Pleural exudates were isolated from 25 patients with TBP and 24 non-TBP patients [malignancy and congestive heart failure (CHF)]. The MCP-1 levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In sera, the MCP-1 levels of TB patients were similar to those of HTRs. For monocytes, CR-TB patients spontaneously expressed more MCP-1, compared with HTRs and E-TB patients. In addition, MCP-1 production of PPD- or 30-kDa antigen-stimulated monocytes was significantly elevated in CR-TB patients than that from E-TB. Interestingly, the E-TB patients had significantly depressed MCP-1 production by PBMCs in response to PPD or 30-kDa, compared with HTRs and CR-TB patients. In pleural effusions, MCP-1 levels were significantly higher in patients with TBP than in patients with CHF, but lower than in malignant effusions.

CONCLUSIONS

The data suggest that MCP-1 production is not uniquely elevated systemically in TB patients, although MCP-1 production might be elevated by monocytes in the chronic phase of TB or with a local pleural infection.

Constrained intracellular survival of Mycobacterium tuberculosis in human dendritic cells

Dendritic cells (DCs) are likely to play a key role in immunity against Mycobacterium tuberculosis, but the fate of the bacterium in these cells is still unknown. Here we report that, unlike macrophages (Mphis), human monocyte-derived DCs are not permissive for the growth of virulent M. tuberculosis H37Rv. Mycobacterial vacuoles are neither acidic nor fused with host cell lysosomes in DCs, in a mode similar to that seen in mycobacterial infection of Mphis. However, uptake of the fluid phase marker dextran, and of transferrin, as well as accumulation of the recycling endosome-specific small GTPase Rab11 onto the mycobacterial phagosome, are almost abolished in infected DCs, but not in Mphis. Moreover, communication between mycobacterial phagosomes and the host-cell biosynthetic pathway is impaired, given that <10% of M. tuberculosis vacuoles in DCs stained for the endoplasmic reticulum-specific proteins Grp78/BiP and calnexin. This correlates with the absence of the fusion factor N-ethylmaleimide-sensitive factor onto the vacuolar membrane in this cell type. Trafficking between the vacuoles and the host cell recycling and biosynthetic pathways is strikingly reduced in DCs, which is likely to impair access of intracellular mycobacteria to essential nutrients and may thus explain the absence of mycobacterial growth in this cell type. This unique location of M. tuberculosis in DCs is compatible with their T lymphocyte-stimulating functions, because M. tuberculosis-infected DCs have the ability to specifically induce cytokine production by autologous T lymphocytes from presensitized individuals. DCs have evolved unique subcellular trafficking mechanisms to achieve their Ag-presenting functions when infected by intracellular mycobacteria.

A meta-analysis of the effect of Bacille Calmette Guérin vaccination on tuberculin skin test measurements

BACKGROUND

The accurate diagnosis of latent tuberculosis infection (LTBI) is an important component of any tuberculosis control programme and depends largely on tuberculin skin testing. The appropriate interpretation of skin test results requires knowledge of the possible confounding factors such as previous BCG vaccination. Uncertainty about the effect of BCG vaccination on tuberculin skin testing and the strength with which recommendations are made to individual patients regarding treatment of LTBI have identified a need to analyse the available data on the effect of BCG on skin testing. A meta-analysis of the evidence for the effect of BCG vaccination on tuberculin skin testing in subjects without active tuberculosis was therefore performed.

METHODS

Medline was searched for English language articles published from 1966 to 1999 using the key words "BCG vaccine", "tuberculin test/PPD", and "skin testing". Bibliographies of relevant articles were reviewed for additional studies that may have been missed in the Medline search. Articles were considered for inclusion in the meta-analysis if they had recorded tuberculin skin test results in subjects who had received BCG vaccination more than 5 years previously and had a concurrent control group. Only prospective studies were considered. The geographical location, number of participants, type of BCG vaccine used, type of tuberculin skin test performed, and the results of the tuberculin skin test were extracted.

RESULTS

The abstracts and titles of 980 articles were identified, 370 full text articles were reviewed, and 26 articles were included in the final analysis. Patients who had received BCG vaccination were more likely to have a positive skin test (5 TU PPD: relative risk (RR) 2.12 (95% confidence interval (CI)1.50 to 3.00); 2 TU RT23: 2.65 [corrected] (95% CI 1.83 to 3.85). The effect of BCG vaccination on PPD skin test results was less after 15 years. Positive skin tests with indurations of >15 mm are more likely to be the result of tuberculous infection than of BCG vaccination.

CONCLUSIONS

In subjects without active tuberculosis, immunisation with BCG significantly increases the likelihood of a positive tuberculin skin test. The interpretation of the skin test therefore needs to be made in the individual clinical context and with evaluation of other risk factors for infection. The size of the induration should also be considered when making recommendations for treatment of latent infection.

Memory functions and death proneness in three CD4+CD45RO+ human T cell subsets

We propose a classification of human CD4(+)CD45RO(+) memory T cells into three new subsets based on cell surface expression levels of CD43. The first subset consists of cells whose CD43 expression is relatively high; this subset also contains the highest proportion of recall Ag-reactive precursors, and its constituent cells respond far more strongly than cells in either of the other subsets to immobilized CD3 Ab in addition to secreting substantially more IFN-gamma and IL-4. Cells of the second subset express similar levels of CD43 to naive cells, and they also respond weakly to TCR-mediated stimuli as judged by either their ability to proliferate or capacity for cytokine production. The third subsets consists of cells whose CD43 expression levels are clearly down-regulated; its cells appear to be anergic to TCR-mediated stimuli, and when examined ex vivo many of them appear to be undergoing either spontaneous apoptosis via a caspase-independent pathway or Fas-mediated apoptosis via a caspase-dependent pathway, even in the resting state. An analysis of telomere lengths revealed that the typical telomere of a cell in the second subset was significantly longer than the typical telomere in the first or third subset. Taken together, these results appear to indicate that CD4(+)CD45RO(+) T cells fall into three functionally differing subsets, one being a subset of cells with fully matured memory phenotype, a second being a less mature subset of cells that retain longer telomeres and whose memory functionality is marginal, and a third consisting of anergic cells that give every appearance of being death-prone and/or in the process of dying.

[Tuberculin-dependent and nonspecific migration activity of leukocytes in astronauts]

There have been presented the results of studying the reactivity of leucocytes with respect to tuberculin and monspecific migration activity of leukocytes in the cosmonatus pre flight and after completion of orbital expeditions of various duration are presented. In some cosmonauts tuberculin rearranged migration of leukocytes. This may bear witness to activisation of the immunity system in response to the antigens which had been already familiar to test-subjects. Experimental data pointed to significant changes in leukocyte mobility in 12 out of 28 cosmonauts examined on days 1 and 7-14 of recovery after the first or repeated long-duration space missions indicating some functional disorders in the phagocytic link which may lead to a typical decline in human resistance to infections.

Peptide-specific T cell response to Mycobacterium tuberculosis: clinical spectrum, compartmentalization, and effect of chemotherapy

The T cell repertoire of 59 patients with untreated tuberculosis was compared with that of 46 bacille Calmette-Guérin-vaccinated controls by assaying the proliferative responses to six permissively recognized peptides from the 16-, 19-, and 38-kDa molecules of Mycobacterium tuberculosis. A trend from higher to lower reactivity following this order: vaccinated controls > lymph node disease > localized extrapulmonary > pulmonary > pleural was seen for 4 of the peptides (P < .03). The decreased response of blood lymphocytes from patients with pleural tuberculosis was partially accounted for by sequestration of peptide-responsive cells within the pleural fluid. Chemotherapy "reversed" the depressed proliferative responses of patients with pulmonary and pleural tuberculosis depending on the peptide origin, being greatest for peptides of 16 kDa, transient for those of 19 kDa, and least for those of 38 kDa. These data demonstrate antigen specificity in the decreased responsiveness of patients with tuberculosis.

Kinetics of purified protein derivative (PPD) proliferation reflects underlying suppressor mechanisms revealed by limiting dilution analysis (LDA) in patients with extrapulmonary tuberculosis (TB)

Mononuclear leucocytes from the blood (PBML) and effusion (EML) of patients undergoing pericardiocentesis were assayed for proliferative response to purified protein derivative of Mycobacterium tuberculosis (PPD). Of the 23 patients tested, 10 had culture-positive tuberculous effusions, while 13 had non-tuberculous aetiologies. Three different kinetic responses were identified: (i) accelerated responses (found in 70% of EML from patients with culture-positive tuberculous effusions); (ii) 'flat' responses (found in 10% of EML from patients with culture-positive tuberculous effusions); and (iii) normal kinetic responses. These differences in kinetic response may reflect underlying immune mechanisms important in the immunopathogenesis of TB. In order to address this possibility we performed LDA on a selection of patients with culture-positive extrapulmonary TB: three patients with accelerated responses, two with normal responses, and one with a 'flat' response. The results confirm the previously reported accumulation of PPD-specific responder cells in the effusion of patients with TB. Cell-mediated suppressor mechanisms (as shown by 'V'-shaped LDA curves) were found in the blood of one patient and the effusion of another. In both cases 'flat' PPD-proliferative responses were observed. However, the LDA data also suggested the presence of in vivo mechanisms limiting the clonal burst size. Thus it appears that immune responses in extrapulmonary TB are influenced by an array of inhibitory mechanisms, modulation of which may influence the outcome of infection.

Conjugation to preadsorbed preactivated proteins and efficient generation of anti peptide antibodies

A solid phase conjugation method is described based on the preadsorption of proteins to aluminium hydroxide adjuvant followed by activation of the adsorbed carrier proteins with iodoacetic acid N-hydroxysuccinimidester or other conjugation reagents. Cysteine-containing peptides were coupled to the iodoacetic acid-activated carrier-adjuvant particles through their SH groups. No dialysis is required since the reaction product is isolated at each step of the procedure by a simple centrifugation and can easily be extensively washed between individual manipulations. The method generates peptide-carrier-adjuvant particles with sterically defined presentation of the peptides at the surface of the particles. When used for immunization of mice and rabbits the conjugates elicited high-titered specific anti-peptide sera, which reacted well with the parent protein in ELISA. The strongest reactions were with the denatured form of the parent protein. On immunoblots antisera to the N- and C-terminus of calreticulin recognized the same M, 52,000 protein.

[Use of flow cytofluorimetry in the analysis of interactions of mononuclear phagocytes with protein antigens]

Flow cytofluorometry of samples stained with fluorochrome-labeled antigen may be used to study the interactions between human blood calls and antigens. Using fluorescein isothiocyanate-labeled tuberculin (after the original method), the authors found that human blood monocytes actively bind labeled tuberculin. Studies of the concentrations from 0.1 to 12,500 ng/ml showed that saturation of the cell capacity for endocytosis is attained at certain doses, after which their surface label prevails. The share of tuberculin-binding lymphocytes was appreciably lower than that of monocytes at the same doses of the antigen. Clinical application of the method for assessing the antigen-presenting function of macrophages is discussed.

Exogenously provided peptides fail to complex with intracellular class II molecules for presentation by antigen-presenting cells

Exogenously supplied antigenic peptides can bind to and be presented by cell surface class II molecules of APCs without prior processing. However, it has been unclear whether peptide Ags exogenously supplied to APCs can also form complexes with nascent intracellular class II molecules that contribute to Ag presentation. We found that exogenously provided peptide Ags, unlike whole protein Ags, are presented as efficiently by fixed as by unfixed B lymphoblastoid APCs, suggesting that intracellular processes do not contribute to the presentation of exogenously supplied peptides by unfixed APCs. Consistent with this finding, exogenously provided peptides do not bind detectably to nascent intracellular class II molecules. We studied the basis for this failure. First, as compared with whole proteins, exogenously supplied peptides accumulate very poorly intracellularly. Second, peptides are more rapidly exocytosed. The limited ability of APCs to accumulate exogenously supplied peptides intracellularly provides a likely explanation for the failure of these peptides to associate with nascent intracellular class II molecules. Exogenously supplied peptides probably never reach the intracellular vesicles in which peptide loading of class II molecules occurs. These findings have implications for the use of peptides therapeutically to block presentation of autoantigens in autoimmune disease.

Immunogenicity of cholecystokinin octapeptide-conjugated antigens in pigs

An improved antigen is required to raise antiserum titers against cholecystokinin higher than those observed in previous studies to demonstrate the effect of immunoneutralization of cholecystokinin on feed intake in swine. Four immunogenic carrier proteins were compared. Unsulfated cholecystokinin octapeptide (CCK8ns) was conjugated to each of human serum globulin (HSG), BSA, Keyhole limpet hemocyanin (KLH), and Tuberculin purified protein derivative (PPD). Forty crossbred swine (four from each of 10 litters, 78 d of age, 22 kg BW) were randomly assigned to the four conjugated antigens by litter. The primary and three booster doses of antigen were injected at 14-d intervals. A blood sample was drawn before the primary dose on d 1 to assess basal nonspecific binding of antigen. Additional blood samples were drawn on d 22, 29, 36, 43, 50, 57, 71, and 92 to follow the time course of antiserum titer expression (d 1 = day of primary dose). Titer is the serum dilution that binds 50% of 1 fmol of radiolabeled antigen. Titers, compared by ANOVA of log titer values, were different between antigens (P < .01) and between litters (P < .01). Mean titer (n = 40; 10 pigs, four samples/pig) during the period after the immune response (d 50, 57, 71, and 92) was 55, 115, 176, and 535 for BSA, HSG, KLH, and PPD, respectively. It is concluded that the carrier protein component has an important effect on immunogenicity of conjugated CCK antigens in pigs; BSA was inferior and KLH and PPD were superior to HSG.

The processing and presentation of mycobacterial antigens by human monocytes

The processing and presentation of whole irradiated Mycobacterium tuberculosis (Mtb gamma) and its purified protein derivative (PPD) by the peripheral blood monocytes from healthy Bacillus Calmette Guérin (BCG)-vaccinated individuals was investigated. To study processing and presentation as events distinct from T cell recognition and proliferation, monocytes were pulsed with antigens for varying time intervals and fixed. The kinetics of presentation indicate that up to 2 h was required for effective presentation of PPD and 2-4 h for Mtb gamma, and that the ability to activate T cells declined as the time interval for which pulsing occurred was increased, so that responses were abolished by 8-10 h. Prefixed monocytes could not present Mtb gamma and PPD to T cells indicating that processing was an essential requisite. Lysosomotropic agents chloroquine, monensin, and leupeptin inhibited the presentation of these antigens suggesting the role of lysosomes/endosomes in processing. Furthermore, monocytes incubated with optimal concentration of antigens for different lengths of time released determinants which were still antigenic but circumvented the need for any further processing. Addition of nonprimed syngeneic monocytes, both untreated or paraformaldehyde fixed to cells which had been pulsed and fixed, restored the responses even at the later time periods when responses were not detected. This second interaction of the monocyte with T cells was not major histocompatibility complex restricted in that the addition of monocytes from another donor was equally effective.

[Investigations on the equivalent of different tuberculin preparations]

Report on the comparison of the effectiveness of seven tuberculin preparations from 6 countries to RT 23. In 2 field trials performed among tuberculous patients with confirmed excretion of tubercle bacilli significant differences have been found among the preparations when their effectiveness and specificity was determined expressed in terms of the rate of negative (0-5 mm) reactions and the size of reaction and its range of variation. Only three of the seven preparations were equivalent to RT 23, one of them was even superior to it; another of the equivalent preparations originated from the stock substance of RT 23. However, one among the deviating preparations originated from RT 23, too, having a threefold higher rate of negative tuberculin reactions. Investigations in the USA with tuberculin preparations from this country done in time parallel to those reported here, had a similar result and the same conclusions. There are set limits to the comparison of testing results with tuberculins of different production. Thus, the comparison of incidence and prevalence of tuberculous infection obtained with different tuberculins must be met only with caution.

Retention of 14C-labeled tuberculin purified protein derivative in the skin of sensitized and nonsensitized animals

Tuberculin purified protein derivative labeled with (14)C ([(14)C]PPD) with a biological potency equivalent to the International Standard for tuberculin PPD was used to study the retention of tuberculin PPD in the skin of sensitized and nonsensitized animals. We found that [(14)C]PPD was almost entirely cleared from the skin test site during the first 18 to 24 h after injection and that when approximately 5% of the initial concentration of [(14)C]PPD was present in the skin test site, the size of the tuberculin skin reaction in sensitized guinea pigs was at its maximum. Furthermore, the addition of 5 or 50 mug of Tween 80 per ml to a solution of PPD did not change either the rate of clearance of PPD from the skin test sites of sensitized guinea pigs or the size of the tuberculin skin reactions. There was no difference in the rate of clearance of [(14)C]PPD from the skin test sites between sensitized and nonsensitized guinea pigs and between guinea pigs of different age. However, there was a significant difference in the rate of clearance of [(14)C]PPD between the guinea pig and the mouse. Finally, the percentage of [(14)C]PPD retained in the site of injection at 24 h was in the neighborhood of 5% of the initial concentration of the solution of PPD injected. The significance of these phenomena is discussed.

Mitogenic factor and migration inhibitory factor in supernatants of serum-free human lymphocyte cultures stimulated with concanavalin A

Incubation of human peripheral blood lymphocytes with Concanavalin A (Con A) in serum-free media results in the generation of soluble active substances which induce DNA synthesis in autologous and allogeneic lymphocytes (mitogenic factor – MF) and inhibit macrophage migration (migration inhibitory factor – MIF). Both substances retain their activity after removal of Con A by binding of Con A to highly polymerized dextrans. Using Sephadex column chromatography, MF and MIF show different elution profiles and can be completely separated from each other. The heterogeneity of MF and the similarity of MIF in molecular weight induced in Con A and PPD stimulated cultures is discussed.

Uptake of radioiodinated antigens by human monocytes

The capacity for human monocytes to take up tuberculin purified protein derivative (PPD) and tetanus toxoid (TT), as well as human serum albumin, transferrin and IgG was studied in vitro. PPD was taken up more avidly and lost from the cells more rapidly than were the other proteins studied. The major fraction of PPD was rapidly degraded. Serum factors inhibited the uptake of the bacterial antigens: PPD uptake was reduced by IgG, albumin and serum, whereas TT uptake was significantly reduced only by whole serum. Although selective binding of the antigens to serum proteins occurred, the binding patterns did not correspond to the patterns of inhibition of antigen uptake induced by serum of its fractions.

Monocytes from patients with active tuberculosis took up significantly less tubercular antigen than did monocytes from normal subjects or patients with inactive tuberculosis.