Phase III trial of 5-fluorouracil and leucovorin plus either 3H1 anti-idiotype monoclonal antibody or placebo in patients with advanced colorectal cancer

BACKGROUND

The monoclonal antibody 3H1 mimics the external structure of the carcinoembryonic antigen (CEA). It therefore has the potential, via the anti-idiotypic network, to stimulate immune responses to CEA that may benefit colorectal cancer patients.

PATIENTS AND METHODS

A total of 630 patients with previously untreated metastatic colorectal cancer were randomised in a 2:1 fashion to receive bolus 5-fluorouracil (5-FU) and leucovorin (LV) plus either 3H1 (n = 422) or placebo (n = 208).

RESULTS

The addition of 3H1 to 5-FU and LV did not result in increased toxicity. Survival for the full intent-to-treat population was 14.7 months for the 3H1 arm and 15.2 months for the placebo arm (P = 0.80). Anti-CEA antibody responses were observed in 70% of patients treated with 3H1. Patients with a negative CEA response had a median survival of 8.3 months (95% CI 7.5-11.0) compared with patients with a strong response: median survival not reached (P <0.001).

CONCLUSION

3H1 is safe and effectively induces immune responses to CEA. Addition of 3H1 to 5-FU and LV was not shown to improve overall patient outcomes. However, improved survival in patients developing anti-CEA responses to 3H1 are provocative and should be studied in further clinical trials.

Cytomorphological study of soft tissue neoplasms: role of fluorescent immunocytochemistry in diagnosis

OBJECTIVES

Exact categorization of soft tissue tumours (STTs) on smears requires application of various ancillary techniques. This study was aimed at evaluating the role of fluorescent immunocytochemistry (FICC) in cyto-diagnosis of 30 STT cases.

METHODS

Thirty cases of soft tissue tumours were included in the present study. All cases were subjected to routine Giemsa and Papanicolaou stain. Extra smears were made and kept for fluorescent immunostaining. A panel of cytoskeletal antibodies, tagged with FITC (Fluorescein isothyocynate), was employed in all these cases. Fluorescent immunostained smears were examined under Zeiss Confocal Laser scanning microscope, using double immunofluorescence (red-green). Finally, all cases were subjected to biopsy and again immunoperoxidase staining.

RESULTS

Among the 30 cases in the present study, unaided cytological diagnoses ranged from 'spindle cell' tumour in four (13.3%) cases, benign and malignant spindle cell tumour in 17 (56.6%) cases, to malignant mesenchymal tumour in nine (30%) cases. FICC helped in further correct categorization of 25/30 (83.3%) cases viz. leiomyoma (three), benign neurogenic tumour (six), schwannoma (one), dermatofibrosarcoma protuberans (three), synovial sarcoma (two), rhabdomyosarcoma (two), malignant fibrous histiocytoma (five) and malignant peripheral nerve sheath tumour (three). Aggressive fibromatosis was found to be a missed diagnosis in two cases. Overall concordance between cyto-diagnosis with FICC, and histopathology results was 83.3% (P < 0.05).

CONCLUSION

Fluorescent immunocytochemistry is a significant ancillary technique for making a rapid and specific diagnosis of STT, as required for their timely management. Incorporation of a wide panel of antibody markers with clinico-cytological correlation is recommended in forming an exact diagnosis in these cases.

'Fast-tracking' cancer referrals: application for periocular basal cell carcinoma

AIM

To study the feasibility of a modified fast-track protocol for periocular basal cell carcinoma (BCC).

METHODS

A modified protocol was set up with an aim to examine all periocular BCCs within 6 weeks of referral to our oculoplastic clinic. An audit of this protocol was performed over a 2-year period.

RESULTS

A total of 65 patients were referred as a 'possible BCC' over the 2-year period. In all, 32 of these patients were referred by dermatologists (49%), followed by fellow consultant ophthalmologists (20 patients, 31%) and general practitioners (11 patients, 17%). The clinical suspicion in the oculoplastic clinic agreed with the referral diagnosis in 71% (46 of the 65) of patients. This figure was particularly high for referrals from dermatologists (84%). In all, 44 out of the 46 'clinically suspected BCC' underwent surgical excision. Histopathology confirmed BCC in 39 of these 44 patients, a diagnostic accuracy of 89%. Among the subgroup of patients referred by the dermatologists, the largest source of referrals, 24 out of 30 patients that underwent surgical excision had histologically proven BCC; a diagnostic accuracy of 80%.

CONCLUSION

Our study shows that the modified fast-track protocol for periocular BCCs is practical and feasible. Such a practice is highly desirable since it prevents a long wait for patients who are aware of a possible malignant periocular lesion.

Late-onset visual decline following successful treatment of subfoveal choroidal neovascularisation with photodynamic therapy

Photodynamic therapy (PDT) has been shown in large studies to be capable of achieving closure of choroidal neovascularization (CNV), thereby resulting in stabilization of visual acuity. We report a series of four patients with classic CNV treated with PDT with good initial result but subsequent severe visual loss that may be related to a change in the morphology of the subretinal scar.

Skin and Psyche : Diversionary Symbiosis

A significant proportion of patients with skin diseases have associated psychosocial factors. Not only does psychopathology manifest on the skin in absence of any real skin disease, primary skin disorders can also be exacerbated by emotional stress adversely influencing the homeostasis of immunological and inflammatory processes in deeper layers of the skin. Furthermore, many patients develop emotional problems as a result of having disfiguring skin diseases. In addition, some patients having solely sensory disturbances in absence of primary dermatoses or identifiable medical or neurological conditions, as well as some purely dermatologic conditions such as post-herpetic neuralgia may preferentially need psychotherapeutic modalities to address their underlying psychopathology irrespective of the presenting dermatologic manifestation arising out of 'somatisation' of a psychopathology into physical problems. The most obvious course of action of referral to a psychiatrist or another mental health professional may unfortunately not be readily tenable either due to the perceived stigma associated with psychiatric illness or lack of insight on the part of patients. In the interregnum, effective management of the psychologic or/and psychiatric problems can only be done by the dermatologist provided he has an adequate knowledge base and experience to undertake psychotherapeutic modalities.

The human polyomavirus, JCV, uses serotonin receptors to infect cells

The human polyomavirus, JCV, causes the fatal demyelinating disease progressive multifocal leukoencephalopathy in immunocompromised patients. We found that the serotonergic receptor 5HT2AR could act as the cellular receptor for JCV on human glial cells. The 5HT2A receptor antagonists inhibited JCV infection, and monoclonal antibodies directed at 5HT2A receptors blocked infection of glial cells by JCV, but not by SV40. Transfection of 5HT2A receptor-negative HeLa cells with a 5HT2A receptor rescued virus infection, and this infection was blocked by antibody to the 5HT2A receptor. A tagged 5HT2A receptor colocalized with labeled JCV in an endosomal compartment following internalization. Serotonin receptor antagonists may thus be useful in the treatment of progressive multifocal leukoencephalopathy.

Ethnic differences in patient perceptions of heart failure and treatment: the West Birmingham heart failure project

OBJECTIVE

To investigate further the hypothesis that ethnic groups would have different levels of knowledge and perceptions of congestive heart failure (CHF) and treatments for this condition, a cross sectional survey was conducted of patients who were attending the heart failure clinics in two teaching hospitals of Birmingham, UK, that serve a multiethnic population.

METHODS

103 patients with CHF (66 men, 37 women) were surveyed by standard questionnaire: 42 were white, 34 Indo-Asian, 22 Afro-Caribbean, and 5 Oriental.

RESULTS

When asked about their beliefs about control of one's health, 22 (64.7%) of Indo-Asians felt that God/fate controlled their health. The majority of white patients tended to believe that the greatest factor influencing their health was the doctor (15 (35.7%)). Of the total study cohort, only 68 (66%) of patients were aware of their primary diagnosis of heart failure; the majority of Indo-Asians (21 (61.8%)) were not aware of their diagnosis. Half of Indo-Asians (17 (50%)) felt that heart failure was not severe, in contrast to 40.9% (n = 9) of Afro-Caribbeans and only 19.1% (n = 8) of white patients. Of the study cohort, 38 (36.9%) were taking their drugs because their doctor told them to, a response most common among the Indo-Asians. The majority of Indo-Asians (22 (64.7%)) and Afro-Caribbeans (14 (63.6%)) stated that they did not have, or did not know whether they had enough, information about their drug. The corresponding figure for white patients was 21.4% (n = 9). When asked whether they took their medication regularly as prescribed, 7 (31.8%) of Afro-Caribbeans reported that they did not take their drugs regularly.

CONCLUSIONS

Our study has highlighted deficiencies in the knowledge of CHF among patients from ethnic minority groups, as well as deficiencies in the information being given to these patients. There is a clear need to invest more in patient education for CHF, with special emphasis on certain high risk subgroups.

Disposable devices for measuring intraocular pressure: a clinical study to assess their accuracy

AIMS

We conducted a study to compare the accuracy of two commercially available disposable tonometry devices (the acrylic biprism, Tonosafe and the silicone shield, Tonoshield) with the standard Goldmann applanation tonometer (GAT).

METHODS

A total of 80 eyes of 40 patients were randomly assigned to two groups. Group A (40 eyes) had the intraocular pressure IOP measured using GAT and the acrylic biprism (Tonosafe), while Group B (40 eyes) had IOP measured using GAT and the disposable silicone shield (Tonoshield). IOP was measured using the GAT both before and after the disposable device and average of the two standard Goldmann readings was compared with the IOP measured using the disposable devices.

RESULTS

The mean difference in IOP in Group A was 0.29 mmHg (SD 0.54) (P=0.0018) while in Group B the mean difference in IOP was 2.09 mmHg (SD 1.23) (P<0.0001). The Altman-Bland method was used to assess the agreement between two methods of clinical measurement. This shows a positive bias of 0.29 (95% confidence interval (CI) 0.11-0.46) when using the disposable acrylic biprism and a positive bias of 2.09 (95% CI 1.69-2.48) with the silicone shield.

CONCLUSION

The IOP recorded using the disposable acrylic biprism (Tonosafe) was in close agreement with the standard GAT. However, IOP readings obtained with the silicone shield (Tonoshield) tend to be higher than with the standard GAT. These facts should be kept in mind when recording IOP in clinical situations.

Caveolin-1 Interacts with 5-HT2A Serotonin Receptors and Profoundly Modulates the Signaling of Selected Gαq-coupled Protein Receptors

5-Hydroxytryptamine 2A (5-HT(2A)) serotonin receptors are important for a variety of functions including vascular smooth muscle contraction, platelet aggregation, and the modulation of perception, cognition, and emotion. In a search for 5-HT(2A) receptor-interacting proteins, we discovered that caveolin-1 (Cav-1), a scaffolding protein enriched in caveolae, complexes with 5-HT(2A) receptors in a number of cell types including C6 glioma cells, transfected HEK-293 cells, and rat brain synaptic membrane preparations. To address the functional significance of this interaction, we performed RNA interference-mediated knockdown of Cav-1 in C6 glioma cells, a cell type that endogenously expresses both 5-HT(2A) receptors and Cav-1. We discovered that the in vitro knockdown of Cav-1 in C6 glioma cells nearly abolished 5-HT(2A) receptor-mediated signal transduction as measured by calcium flux assays. RNA interference-mediated knockdown of Cav-1 also greatly attenuated endogenous Galpha(q)-coupled P2Y purinergic receptor-mediated signaling without altering the signaling of PAR-1 thrombin receptors. Cav-1 appeared to modulate 5-HT(2A) signaling by facilitating the interaction of 5-HT(2A) receptors with Galpha(q). These studies provide compelling evidence for a prominent role of Cav-1 in regulating the functional activity of not only 5-HT(2A) serotonin receptors but also selected Galpha(q)-coupled receptors.

Physiology ofAnabaena khannae andChlorococcum humicola under fluoride stress

Sodium fluoride showed pH-dependent physiological responses in the two test microalgae Anabaena khannae and Chlorococcum humicola. A. khannae showed severe membrane damage with fluoride at low pH with leakage of pigments and electrolytes. Annihilation of photosynthesis along with inhibition in 14C uptake was observed at pH 6 with 50 mg/L fluoride. While respiration was less affected in the cyanobacterium, C. humicola showed 30 % inhibition in respiratory activity. Resistance of C. humicola to fluoride toxicity has been attributed to the hindrance provided by the thick cell envelope, intracellular compartmentation and increase in extracellular pH as a consequence of its metabolism.

Caspase 1 and caspase 8 in HIV infected patients with and without tuberculosis

BACKGROUND

Caspase 8 is involved in apoptosis mediated by Fas and p55 tumor necrosis factor receptor ligation in HIV infection. Apoptosis is partially mediated by interleukin-1beta-converting enzyme (caspase-1).

AIMS

We determined apoptosis, using caspase-1 and caspase-8, among patients with HIV infection, with and without tuberculosis (TB), those with TB alone and healthy individuals.

SETTING AND DESIGN

Cross-sectional analysis of caspase-1 and caspase-8 among patients with HIV infection, with and without TB, those with TB alone and healthy individuals.

MATERIALS AND METHODS

Nineteen HIV infected patients with TB (HIV+/TB+) and 20 with HIV infection without TB (HIV+/TB-) were studied. Fifteen individuals with TB alone were disease controls (HIV-/TB+) and 20 were healthy controls (HIV-/TB-). Caspases were measured by single-step ELISA using commercially available monoclonal antibodies.

STATISTICAL ANALYSIS

Two-way ANOVA and Pearson's correlation coefficient.

RESULTS

Mean CD4 counts of HIV+/TB+ were lower than HIV+/TB- (p<0.05). OD value of caspase 1 in HIV+/TB+ was 0.295+0.05, while that in HIV+/TB- it was 0.302+0.18. It was 0.293+0.07 in HIV-/TB+ and in HIV-/TB- the values were 0.287+0.06. OD value of caspase 8 in HIV+/TB+ was 0.307+ 0.07, lower than HIV+/TB- (0.927+0.25). It was 0.008+0.03 in HIV-/TB+ and in HIV-/TB-, 0.074+0.004. Values of caspase 8 in patients with HIV infection (with/without TB) were higher than those with TB alone or healthy individuals (p<0.01). Levels of caspase 8 in HIV+/TB- were higher than patients with HIV+/TB+ (p<0.01).

CONCLUSION

Levels of caspase-1 are not different irrespective of presence or otherwise of TB and HIV infection. Fas-related apoptosis is higher in HIV infection. With concomitant TB, levels of caspase 8 were lower as compared with those without TB.

Beta2 microglobulin as a surrogate marker for HIV infection: good correlation with CD4 counts

To determine if beta-2 microglobulin (beta2M) levels were elevated in our HIV infected patient population and if it could be used as a surrogate marker for disease progression. Thirty-eight HIV infected individuals and 26 age and sex-matched controls were studied. Measurement of CD4 cell count was carried out on a flowcytometer using anti-human CD4 monoclonal antibody and beta2M was measured by an enzyme immunoassay. Mean levels of HIV infected individuals were 1.29 +/- 0.52 mg/L and were significantly higher than 0.74 +/- 0.07 mg/L, the value of controls (p value <0.01). There was a negative correlation between CD4 counts and beta2M levels (r-value-0.79, p value <0.001). Beta2M levels in HIV infected individuals who have no opportunistic infection are elevated and these levels correlate with the CD4 counts. Beta2M can be used for the clinical follow-up of patients with HIV infection.

Removal of 2-fluoro and 2-iodophenol from aqueous solutions using industrial wastes

A comparative study of the adsorbents prepared from several industrial wastes for the removal of 2-fluorophenol and 2-iodophenol has been carried out. The results show that maximum adsorption on carbonaceous adsorbent prepared from fertilizer industry waste has been found to be 35.3 and 235.3 mg g(-1) for 2-fluorophenol and 2-iodophenol, respectively. Compared to carbonaceous adsorbent, the other three adsorbents (viz., blast furnace sludge, dust, and slag) adsorb phenols to a much smaller extent. This has been attributed to the carbonaceous adsorbent having a larger porosity and consequently higher surface area. The adsorption of phenols on this adsorbent has been studied as a function of contact time, concentration and temperature. The adsorption has been found to be endothermic, and the data conform to the Langmuir equation. The further analysis of data indicates that adsorption is a first order process and pore diffusion controlled. A comparative study of adsorption results with those obtained on standard activated charcoal sample shows that prepared adsorbent is about 45% as efficient as standard activated charcoal and therefore, can be fruitfully employed for the removal of phenolic pollutants from wastewaters.

Animal models of hepatic encephalopathy

Hepatic encephalopathy is a neuropsychiatric syndrome associated with acute liver failure, chronic parenchymal liver disease, or portosystemic anastomosis. Many approaches have been used to develop suitable models of hepatic encephalopathy, each with specific advantages and disadvantages. The most commonly used models have been the surgical hepatectomy and liver devascularization procedures, and hepatotoxins such as galactosamine and acetaminophen. Drug-toxicity models may be clinically more relevant. The specific requirements of experiments to study a particular aspect of encephalopathy also influence the choice of animal model. Animal models will play a central role in future research into hepatic encephalopathy to better understand its pathophysiology and to develop newer therapeutic modalities for this condition.

Parkin-deficient mice exhibit nigrostriatal deficits but not loss of dopaminergic neurons

Loss-of-function mutations in parkin are the major cause of early-onset familial Parkinson's disease. To investigate the pathogenic mechanism by which loss of parkin function causes Parkinson's disease, we generated a mouse model bearing a germline disruption in parkin. Parkin-/- mice are viable and exhibit grossly normal brain morphology. Quantitative in vivo microdialysis revealed an increase in extracellular dopamine concentration in the striatum of parkin-/- mice. Intracellular recordings of medium-sized striatal spiny neurons showed that greater currents are required to induce synaptic responses, suggesting a reduction in synaptic excitability in the absence of parkin. Furthermore, parkin-/- mice exhibit deficits in behavioral paradigms sensitive to dysfunction of the nigrostriatal pathway. The number of dopaminergic neurons in the substantia nigra of parkin-/- mice, however, is normal up to the age of 24 months, in contrast to the substantial loss of nigral neurons characteristic of Parkinson's disease. Steady-state levels of CDCrel-1, synphilin-1, and alpha-synuclein, which were identified previously as substrates of the E3 ubiquitin ligase activity of parkin, are unaltered in parkin-/- brains. Together these findings provide the first evidence for a novel role of parkin in dopamine regulation and nigrostriatal function, and a non-essential role of parkin in the survival of nigral neurons in mice.

Effect of different aspirin doses on platelet aggregation in patients with stable coronary artery disease

BACKGROUND

Aspirin is widely used as an antiplatelet agent in the primary and secondary prevention of cardiovascular disease. In order to spare prostacyclin formation and reduce gastrointestinal side-effects, very low doses of aspirin have been introduced. However, it remains unclear whether these low doses are equally effective with respect to inhibition of platelet aggregation.

AIMS

In a randomized, controlled study in 60 patients with stable coronary artery disease, the effects on platelet aggregation of five doses (50, 80, 100, 162.5 and 325 mg) of aspirin, which are widely used in clinical practice, given for 70 days, were investigated. Two reagents, adenosine diphosphate (ADP) and epinephrine, were used to induce platelet aggregation in platelet-rich plasma. An age- and sex-matched group of people without coronary artery disease served as the control.

RESULTS

ADP- and epinephrine-induced platelet aggregation was 78.2 +/- 12.8% and 76.7 +/- 15.5% of maximum aggregation in the control group. Aspirin inhibited platelet aggregation in a dose-dependent manner. Minimum platelet aggregation was observed at a dose of 325 mg aspirin (27.5 +/- 17.4% with ADP). Doses of 50 and 80 mg aspirin were much less effective in inhibiting platelet aggregation (59.1 +/- 11.4% and 50.3 +/- 12.1% with ADP, respectively). Doses of 100 and 162.5 mg aspirin produced significantly greater inhibition of platelet aggregation than lower doses (36.2 +/- 11.7% and 38.5 +/- 19.8% platelet aggregation with ADP, respectively).

CONCLUSION

Our results demonstrate that doses of aspirin less than 100 mg are not as effective at inhibiting platelet aggregation as doses greater than 100 mg.

Utilization of industrial waste products as adsorbents for the removal of dyes

A number of low cost adsorbents from steel and fertilizer industries wastes have been prepared and investigated for the removal of anionic dyes such as ethyl orange, metanil yellow and acid blue 113 from aqueous solutions. The results indicate that inorganic wastes, i.e. blast furnace dust, sludge and slag from steel plants are not suitable for the removal of organic materials, whereas a carbonaceous adsorbent prepared from carbon slurry of fertilizer industry was found to adsorb 198, 211 and 219mg/g of ethyl orange, metanil yellow and acid blue 113, respectively. The adsorption of dyes on this adsorbent was studied as a function of contact time, concentration, particle size and temperature by batch method. The adsorption isotherm conformed to Langmuir model and the adsorption was found to be exothermic and physical in nature. Kinetic data conforms to Lagergren's equation with good correlation coefficients varying from 0.9998 to 0.9999 indicating that the adsorption is a first-order process. The adsorption data on carbonaceous adsorbent was compared to a standard activated charcoal sample and it was found that the prepared adsorbent is about 80% as efficient as standard activated charcoal and therefore, can be used as low cost alternative ( approximately 100 US dollars per ton) for colour removal from effluents.

The interaction of a constitutively active arrestin with the arrestin-insensitive 5-HT(2A) receptor induces agonist-independent internalization

5-HT(2A) serotonin receptors are unusual among G-protein coupled receptors in that they can be internalized and desensitized, in some cell types, in an arrestin-independent manner. The molecular basis of the arrestin-insensitivity of 5-HT(2A) receptors is unknown but is probably caused, in part, by the apparent lack of agonist-induced 5-HT(2A) receptor phosphorylation. Because the arrestin-insensitivity of 5-HT(2A) receptors is cell-type selective, we used a "constitutively active" arrestin mutant that can interact with agonist-activated but nonphosphorylated receptors. We show here that this "constitutively active" arrestin mutant (Arr2-R169E) can force 5-HT(2A) receptors to be regulated by arrestins. Cotransfection of 5-HT(2A) receptors with Arr2-R169E induced agonist-independent 5-HT(2A) receptor internalization, and a constitutive translocation of the Arr2-R169E mutant to the plasma membrane, whereas wild-type Arrestin-2 had no effect. Additionally, Arr2-R169E, unlike wild-type arrestin-2, induced a significant decrease in efficacy of agonist-induced phosphoinositide hydrolysis with an unexpected increase in agonist potency. Radioligand binding assays demonstrated that the fraction of receptors in the high-affinity agonist binding-state increased with expression of Arr2-R169E, indicating that Arr2-R169E stabilizes the agonist-high affinity state of the 5-HT(2A) receptor (R*). Intriguingly, the agonist-independent interaction of Arr2-R169E with 5-HT(2A) receptors was inhibited by inverse agonist treatment and is thus probably caused by the high level of 5-HT(2A) receptor constitutive activity. This is the first demonstration that a constitutively active arrestin mutant can both induce agonist-independent internalization and stabilize the agonist-high affinity state of an arrestin-insensitive G protein coupled receptor.

Reduced apoptosis by pentoxiphylline among patients with HIV infection

BACKGROUND

Apoptosis is a significant cause of CD4(+) T cell death. Caspase 8 (FLICE) is involved in apoptosis mediated by Fas and p55 tumor necrosis factor (TNF) receptor ligation. It is also partially mediated by interleukin-1beta (IL-1beta)-converting enzyme (ICE; caspase 1). We and others have shown that pentoxiphylline inhibits TNF-alpha. We used it among patients with HIV infection to determine if 24 weeks of therapy altered the levels of caspase 1 and caspase 8.

PATIENTS AND METHODS

Nineteen HIV-infected patients having no opportunistic infection at the time of recruitment were administered pentoxiphylline 400 mg thrice daily for 24 weeks. Caspase levels were measured using a single-step ELISA using commercially available monoclonal antibodies against caspase 1 and caspase 8.

RESULTS

Mean CD4 counts of the patients were 202.6+/-111.6 (/mm(3)). Mean OD value of caspase 1 among patients before therapy was 0.302+/-0.197 and was higher than that of controls (0.287+/-0.064), but this was not statistically significant. Following 24 weeks of therapy with pentoxiphylline, the OD value declined significantly to 0.164+/-0.028 among patients (p<0.001). Mean OD value of caspase 8 among patients prior to therapy was 0.927+/-0.249. This was significantly higher than that of controls, whose level was 0.0074+/-0.004 (p<0.001). Following 24 weeks of therapy with pentoxiphylline, the OD value declined to 0.199+/-0.064 among patients and this was significantly lower than the value at the start of treatment (p<0.001).

CONCLUSION

Therapy with pentoxiphylline for 24 weeks is associated with a decline in the levels of caspase 1 and caspase 8. Since the drug is known to produce TNF inhibition, this might result in reduced apoptosis and an improved CD4 lymphocyte survival.

Influence of Mycobacterium tuberculosis on differential activation of helper T-cells

Host defence against tuberculosis infection involves T-lymphocyte mediated cellular immune responses. In this study we assessed T-cell activation by studying the early signal transduction events and production of cytokines by human CD4+ T-cells. The study constituted of five groups of subjects: (a) untreated acid fast bacilli (AFB)+ve TB patients who have not started anti-tuberculosis therapy (ATT) [New]; (b) patients who have taken ATT for two months [2T]; (c) patients who have taken ATT for six months [6T]; (d) mantoux positive healthy controls [T+ve]; (e) mantoux negative healthy controls [T-ve]. We found that mantoux positive healthy controls produced significantly higher levels of IP3, intracellular Ca2+ and presented increased PKC activity when CD4+ T-cells were stimulated with M. tuberculosis H37Rv cell lysate as compared to mantoux negative controls. Furthermore, decreased expression of CD54 (ICAM-1) and reduced [Ca2+]i were seen in TB patients as compared to T+ve healthy controls. TB patients showed significantly lower levels of IL-2 and IFNgamma and higher levels of IL-4 as compared to normal healthy controls, suggesting a diminished Th1 response. Thus, the reciprocal changes in cytokines, reduced [Ca2+]i levels, and CD54 expression in patients imply phenotype shifting of Th precursors to Th2 type in TB patients.