Detection of tubercular antibody and antigen in sera of bone and joint tuberculosis

Trichloroacetic acid (TCA) solubilized and DEAE fractionatedMycobacterium tuberculosis H₃₇Ra excretory-secretory (ES) antigen viz., Mtb EST DE1 and affinity purified goat antibodies to the TCA solubilized ES antigen (Mtb EST) were explored in detecting tubercular antibody and antigen respectively in sera of bone and joint tuberculosis by indirect and sandwich ELISA. Out of total 36 bone & joint tuberculosis cases, tubercular antibody was detected by indirect ELISA in 30 patients (sensitivity 83%), while circulating tubercular antigen was detected by sandwich ELISA in 27 patients (sensitivity 75%). Out of 34 non tubercular disease control cases, 10 patients showed positive reaction for antibody while only 4 patients showed positive reaction for antigen. In another group of 34 healthy subjects who were screened, 4 individuals showed positive reaction for tubercular antibody and 2 cases for antigen. This study shows that antigen detection assay using affinity purified anti Mtb EST antigen antibody is superior with overall specificity of 91% as compared to antibody detection assay with 75% specificity in bone & joint tuberculosis.     

<Emphasis Type="Italic">In vitro</Emphasis> released antigens in diagnosis and immunomonitoring of filaria and tuberculosis

In vitro released antigens by living parasites or bacteria underin vitro maintenance or short term culture showing specific humoral immune response have been explored in development of immunodiagnostics for infectious diseases such as filariasis and tuberculosis in our laboratory. ELISA usingB. malayi mf ES antigen has been explored for detecting IgG antibody by Indirect ELISA and antigen by Inhibition ELISA and in immunomonitoring of carriers as well as clinical filarial cases. A ten year follow up of mf carriers with DEC therapy showed disapperance of antigen and antibody followed by reappearance in few cases in an endemic area. None of the cases followed developed clinical symptoms suggesting the need for long term monitoring and treatment of microfilaraemic carriers. Further immunomonitoring was found to be useful in confirming filaria aetiology in the absence of microfilaremia and determining appropriate period of treatment of acute, early clinical and occult filarial infections for clinical relief and cure.Indirect Stick Penicillinase ELISA system using Mtb EST-6 antigen for detecting tuberculous IgG antibody and a Sandwich Penicillinase ELISA system using affinity purified antibody for detecting circulating antigen were explored in tuberculosis. A combination of both the assay systems with a sensitivity of 70% and specificity of 98% was found to be promising in the precise diagnosis of pulmonary tuberculosis. Further antigen detection was found to be useful in bone and joint tuberculosis.     

Mycobacterium tuberculosis H37Ra ESAS-7—An excretory-secretory antigen fraction of immunodiagnostic potential in pulmonary tuberculosis

A mycobacterial excretory-secretory protein fraction ESAS-7 purified by 50% ammonium sulphate precipitation followed by SDS-PAGE fractionation was evaluated by penicillinase enzyme linked immuno-sorbent assay (ELISA) for its sensitivity and specificity in the diagnosis of pulmonary tuberculosis. At a “cut off” serum dilution of 600, 38 (90%) of 42 sera from bacteriologically confirmed tuberculosis cases, 15 (100%) of 15 sera from bacteriogically negative but anti tubercular therapy (ATT) responded cases, 3 (7%) of 43 sera from normal healthy subjects and 4 (8%) of 48 sera from non tuberculous disease control cases gave positive reaction for tubercular antibody to ESAS-7 antigen fraction containing predominantly 33-kDa protein with a sensitivity of 90% in bacteriologically confirmed cases and specificity of 92%. Further, this diagnostic assay using the ESAS-7 antigen is more sensitive requiring as little as one nanogram antigen per test compared to use of 100 nanogram EST-6 antigen reported earlier. Thus use of ESAS-7 antigen for antibody detection has good diagnostic potential with improved specificity in pulmonary tuberculosis.     

Serodiagnosis of tuberculosis using two ELISA systems

Serodiagnosis by ELISA has been widely explored over the years, in the diagnosis of tuberculosis. Two ELISA systems were evaluated for detection of mycobacterial antibodies in pulmonary and extra pulmonary tuberculosis. The two test assays explored were ERBA LISA (TB IgG) test (Anda Biologicals) which uses A60 antigen complex found in the cytosol of typical and atypical mycobacteria, and SEVA TB (IgG) ELISA, which uses a 31 kDa, glycoprotein antigen purified fromM. tb H₃₇Ra culture filtrate. Sera from 98 proven tuberculosis [pulmonary TB (48), tuberculous lymphadenopathy (30), tuberculous meningitis (15) & genitourinary TB (5)] were studied along with 32 healthy controls. The overall positivity obtained using ERBA LISA (TB IgG) test and SEVA TB (IgG) ELISA test was 72.9% and 91.6% in pulmonary tuberculosis, 43.3% and 76.6% in tuberculous lymphadenopathy respectively. The sensitivity of ERBA LISA test in tuberculous meningitis and genito-urinary TB was significantly low (26.6% & 40% respectively) compared to sensitivity obtained using SEVA TB ELISA (86.6% & 60% respectively) with overall specificity of 60% and 87.5%. Thus SEVA TB IgG ELISA test was found to be more sensitive than ERBA LISA in detecting IgG antibodies in tuberculous sera, in particular in extra pulmonary tuberculosis cases.     

Potential of mycobacterial excretory secretory protein antigens (sevatb ES-31, ES-43, EST-6 and ES-20) as biomarkers to detect <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis> bacilli

There is a need for a simple and reliable method to identify Mycobacterium tuberculosis from nontuberculous mycobacteria (NTM). The utility of mycobacterial ES-31, ES-43, EST-6 or ES-20 antigen as a biomarker for differentiation of Mycobacterium tuberculosis bacilli from nontuberculous mycobacteria was explored using Fluorescein isothiocyanate conjugated antibodies against these antigens. Detection of these antigens was done from M.tb H₃₇Ra and H₃₇Rv DSS antigen. The presence of antigen in bacilli using FITC labelled antibody was indicated by green fluorescence on the cell surface while, its absence by no fluorescence under microscope. In M.tb H₃₇Ra and H₃₇Rv bacilli, fluorescence was observed on addition of FITC labelled anti ES-31 and anti ES-43 antibody; whereas no fluorescence was observed in case of EST-6 and ES-20 antibody conjugates. However all the antigens were detected in detergent soluble sonicate antigen of tubercle bacilli on addition of FITC conjugates. Fluorescence was not observed for ES-31, ES-43, EST-6 and ES-20 antigen in any of the tested NTM as well as in Escherichia coli. SEVA TB ES-31 and ES-43 may be used as biomarkers to distinguish M.tuberculosis bacilli from NTM.     

Assay of tubercular antibody, circulating free and immune complexed antigen in the diagnosis of pulmonary tuberculosis

Analysis of tubercular antibody, circulating free and immune complexed antigen (CIC-Ag) was done in confimed pulmonary tuberculosis sera by ELISA, using ES-31 antigen and affinity purified anti ES-31 antibody. Twenty three of 25 (92%) tuberculosis sera were positive for IgG antibody to ES-31 antigen. Using anti ES-31 antibody, free tubercular antigen could be detected in 20 of 25 (80%) cases whereas circulating immune complexed antigen (CIC-Ag) in 18 of 25 (72%) cases by sandwich ELISA. Of the two sera showing absence of antibody, one showed presence of free and CIC-Ag whereas the other showed the presence of free antigen. Thus antigen assay may be used as an adjunct tool for confirmation of pulmonary tuberculosis.     

Immunodiagnosis of tuberculosis: An update

Tuberculosis is still a major health problem in most developing countries and its incidence is rising in many developed countries. This resurgence has been attributed to the HIV epidemic and TB has been declared as a global health emergency by WHO in 1993. The diagnosis of tuberculosis mainly depends upon initial clinical suspicion and radiographic findings with subsequent bacteriological confirmation by sputum smear examination and culture. Lack of sensitivity in smear examination, non specificity of radiological findings, extended tum around time ofMycobacterium tuberculosis culture and difficulties in diagnosing paucibacillary, childhood and extrapulmonary tuberculosis has necessitated to explore the utility of immunodiagnosis of tuberculosis as a convenient and cost effective test to supplement clinical information for definite diagnosis. Many commercial tests are available in the market for diagnosis of TB. Most of these tests are based on the detection of IgG, IgA and IgM antibodies to specific mycobacterial antigen or mixture of antigens. Indigenous immunoassay systems have explored excretory-secretory ES-31 mycobacterial antigen for immunodiagnosis of TB. Many a time there is lack of consistent elevation in all the three Ig classes in active infection thus making it more important to determine the ideal antibody isotype assay for reliable diagnosis of tuberculosis and to save the costs of the patient for unnecessary investigations.     

Evaluation of A60 antibodies in pulmonary and neurotuberculosis

Humoral immune response against PPD derived A60 antigen was evaluated by quantification of serum A60 antibodies in thrity healthy adults not exposed to tuberculosis (Group 1), in twenty seven healthy adults exposed to tuberculosis patients i.e. staff working in wards of tuberculosis hospital for one to thirty years (group 2), in twenty five pulmonary tuberculosis patients admitted to the Institute for Chest Diseases, Hyderabad (Group 3) and in sixty neurotuberculosis patients admitted to Neurosurgery department of our institute (Group 4). Highly significant elevation of A60 antibodies was observed in pulmonary tuberculosis patients (p<0.01) compared to healthy adult groups. A significant elevation in serum was also observed in case of neurotuberculosis group compared to both healthy groups (p<0.01). A test on A60 antibodies in serum gavv a sensitivity of 100%, specificity of 96.6%, positive predictive value of 81% and negative predictive value of 100% for pulmonary tuberculosis, whereas a sensitivity of 58%, positive predictive value of 79% and negative predictive value of 75% were noted for neurotuberculosis patients. Results of A60 antibodies in ten cerebrospinal fluids (CSF) obtained from non tuberculosis patients and thirty two CSF from patients of neurotuberculosis did not show significant elevation of antibodies. However the ninetyfive percentile value of CSF A60 antibodies was higher in neurotuberculosis (7.4 U/ml) group compared to nontuberculous group (3.8 U/ml) and the test showed a good positive predictive value (83%), very low negative predictive value (25%) and low sensitivity (63%). Serum A60 antibody assay appears to be a good serological marker available today for pulmonary tuberculosis and a supportive marker for neurotuberculosis.     

Diagnostic role of the antibody response to the 38kDa, 16kDa proteins and lipoarabinomannan of mycobacterium tuberculosis

The antibody response to the 38kDa, 16kDa and Lipoarabinomannan (LAM) antigens ofMycobacterium tuberculosis was evaluated using three different ELISAs based on these antigens. The study group included tuberculosis patients (n=52), patients with HIV and TB co-infection (n=10), other chest symptomatics (n=5), HIV infected individuals (n=10), leprosy cases (n=7) and healthy controls (n=75). The results indicate that the 38kDa and LAM based ELISA for IgM/IgG has a low specificity (ranging from 69–85%) and sensitivity (ranging from 55–78%). When three ELISAs are carried out on a single patient the probability of detection of tuberculosis was significantly increased to 95.2% indicating that a single ELISA test is of low sensitivity and that a combination of ELISA’s may be needed to be of any value as a diagnostic test for tuberculosis. Additionally, a western blot assay of the serum antibody response to protein fraction ofM. tuberculosis was analysed in 15 tuberculosis patients and five healthy controls. A multiple antibody response to various M.tuberculosis proteins was observed which varied from patient to patient as compared to controls who showed a single 38–39 kDa protein band positivity. These finding suggest that a western blot assay which determines the antibody response to a set of antigenic components ofM. tuberculosis could be a better serological test for the diagnosis of tuberculosis in our population.     

Determination of immunoreactivity of<Emphasis Type="Italic">Plasmodium falciparum</Emphasis> antigens,serum dilutions and biomaterials

Immunoreactivity properties of serum dilutions andPlasmodium falciparum malaria antigens were measured and compared by ELISA technique using different ELISA plates to evaluate the role of antigens and serum dilutions for optimum binding. Also effort has been made to see the effect of reaction surface and material i.e. ELISA plates for binding capacity. Serological properties were estimated by ELISA methods for detection of malaria and determination of immunological characteristics. Three Pf antigens (PfAg) i.e. ring infected erythrocyte surface antigen: AR-1 (RESA), histidine-rich protein 2 antigen (HRP-2) and glycophospholipid antigen (grown and developed Pf antigen from PSJ-M strain): GPL1 have been used for serological testing of human blood samples by Enzyme Link Immunosorbant Assay (ELISA). 1∶100, 1∶1000 and 1∶10000 dilutions of Pf positive and negative serum (50 samples in each group) and 1∶1000 dilution of Pf antigens were used to measure immunoreactive properties by ELISA method. Result of PfAg-serum immunoreactivity study showed that GPL1 has the highest degree of immuno binding reactivity compared to other Pf antigens. HRP-2 and RESA antigens showed no significant difference to each other. Study also found that Costar and Fastec ELISA plates have a better Ag−Ab binding capability compared to immulon and Falcon plates at all dilutions of serum. Serum dilution of 1∶100 showed best binding and reactivity with Pf antigens followed by 1∶1000 and 1∶10000 showed lowest reactivity.     

Circadian periodicity of plasma lipid peroxides and anti-oxidant enzymes in pulmonary tuberculosis

The circadian periodicity of plasma lipid peroxide levels and activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were studied in 50 clinically, bacteriologically and radiologically proven fresh cases of pulmonary tuberculosis (age: 21–45 years) and 60 age-matched healthy volunteers with diurnal activity from 06∶00 to about 22∶00 and nocturnal rest. A marked circadian variation in plasma lipid peroxide level was recorded in healthy subjects and pulmonary tuberculosis patients with significant amplitude and acrophase around 16∶21 and 17∶12 respectively. The acrophase tended to be delayed in tuberculosis patients. Furthermore, a statistically significant circadian rhythm was found in SOD, CAT and GPx activities in normal volunteers and pulmonary tuberculopsis patients. SOD and CAT enzyme activity was noted to be maximum at 06∶00 and minimum at 00∶00 in tuberculosis patients. The circadian acrophase for GPx activity was recorded at 16∶15 in normals and around 22∶45 in patients. Moreover, the activity was found to be decreased at all sampling hours during 24-hours sleep-awake period in patients in comparison to healthy counterparts. The MESOR and circadian amplitude also decreased markedly. The decreased activity of measured antioxidant enzymes in pulmonary tuberculosis patients could probably be associated with oxidative stress and/or decreased anti-oxidant defensive mechanism in such patients.     

Analysis of SEVA TB ES-31 antigen specific immunoglobulins IgM, IgA and IgG in sera of sputum and culture positive pulmonary tuberculosis

Tuberculosis remains major health problem in India and developing countries Immunodiagnosis has important role in screening, diagnosis and management of tuberculosis. SEVA TB ES-31 antigen has shown potential in detecting tuberculous IgG antibody in earlier studies from our laboratory. In the present study we have analysedSEVA TB ES-31 antigen specific immunoglobulinsIgM, IgA and IgG in clinically and bacteriologically confirmed pulmonary tuberculosis cases to determine the usefulness of specific immunoglobulin class in the diagnosis of patients attending the hospital. Of the 30 cases of pulmonary tuberculosis 25 (83.3%) were positive for IgG, 19 (63.3%) for IgM and 16 (53.3%) for IgA. On combining IgG and IgM positivity, sensitivity was increased to 93.3%. While combining IgG and IgA positivity, sensitivity increased to 90%. However specificity was decreased to 66.6% and 70% for both of these combinations respectively. It could be envisaged from this study that IgG antibody detection against ES-31 antigen showed acceptable sensitivity (83.3%) and specificity (86.6%) compared to IgM or IgA alone or in combination. When immune responses were analysed according to degree of sputum positivity, IgG response was observed to be predominant in all grades, compared to IgM or IgA antibody. The addition of IgM or IgA as an adjunct test increases the sensitivity but at the cost of specificity. Hence the detection of IgG alone is more useful compared to IgM or IgA assay, in detecting tuberculosis disease cases coming to the hospital.     

Direct diagnosis ofMycobacterium tuberculosis in blood samples of HIV infected patients by polymerase chain reaction

We have developed a simple, economical and reproducible method for processing blood samples from HIV infected patients for diagnosis of tuberculosis. The procedure was validated on 55 samples selected for tuberculosis based on clinical criteria. 52 patients had radiological changes indicative of pulmonary tuberculosis of which only 28 were positive for AFB in sputum (sensitivity 54%) and 27 for tuberculin (sensitivity 52%). 26 HIV positive patients who showed positive X-ray did not react to tuberculin. The genus PCR probe missed 3 samples (sensitivity 94%) compared to X-ray.M.tuberculosis was detected in the blood of all X-ray positive cases by PCR using TB400 probe (sensitivity 100%) and another probe forM. tuberculosis, IS6110, missed 6 of them (sensitivity 88% compared to X-ray and 89% compared to TB400). It is proposed that this simple sample processing method could be used to screen all blood samples quickly for mycobacteremia using the genus PCR and only those positive for mycobacteria need to be tested forM.tuberculosis. This would save the scarce resources and time by reducing significantly the number of samples to be screened for species confirmation.     

Utility of serum LDH isoforms in the assessment of mycobacterium tuberculosis induced pathology in TB patients of Sahariya tribe

The present study was carried out in the Sahariya tribe of Central India, which reportedly have high prevalence of pulmonary tuberculosis. Total serum LDH and its tissue specific isoforms were estimated in TB patients and matched healthy controls to test the utility of LDH as diagnostic marker for tuberculosis. About 210 sputum positive cases and 328 age and sex matched sputum negative controls were recruited. The spectrophotometeric and densitometric analysis of each LDH isoform was carried out in both cases and controls. The mean values of serum LDH were estimated and compared for each class by t-test. The statistical comparisons were made between sputum negative controls and sputum positive cases by Mann-Whitney’s U test. The spectrophotometric estimation of serum LDH revealed significant (P=0.0016) increase in its level in cases (290 IU/L) as compared to controls (248 IU/L). The densitometric analysis of individual LDH isoforms in cases and controls demonstrated significant elevation in LDH1 (P>0.05), LDH2 (P>0.05) and LDH3 (P<0.005) in sputum positive cases in comparison to sputum negative controls. Our study revealed a positive correlation between serum LDH level and the presence of mycobacteria and their load, suggesting utility of LDH as an important diagnostic marker of tuberculosis induced stress, at least in tribal areas lacking access to modern clinical tests.     

Seroprevalence of SARS-CoV-2 in Croatian solid-organ transplant recipients

IntroductionThe data on the coronavirus disease (COVID-19) in solid-organ transplant recipients (SOTRs) in Croatia is unknown. The aim of this study was to analyze the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Croatian SOTRs.Materials and methodsFrom 7 September to 27 November 2020 (beginning of the second COVID-19 pandemic wave), a cross-sectional screening for COVID-19 was performed in the adult outpatient liver (LTRs; N = 280) and kidney transplant recipients (KTRs; N = 232). Serum samples were initially tested for SARS-CoV-2 IgG antibodies using a commercial enzyme-linked immunosorbent assay (ELISA; Vircell Microbiologists, Granada, Spain). All positive samples were confirmed using a virus neutralization test (VNT). Data on risk exposure and COVID-19 related symptoms were collected using a questionnaire.ResultsThe transplanted cohort’s seroprevalence detected by ELISA and VNT was 20.1% and 3.1%, respectively. Neutralizing (NT) antibodies developed in 15.6% of anti-SARS-CoV-2 ELISA IgG positive SOTRs. The difference in seropositivity rates between LTRs and KTRs was not statistically significant (ELISA 21.1% vs. 19.0%, P = 0.554; VNT 3.6% vs. 2.6%, P = 0.082). Overall VNT positivity rates were higher in patients who reported participation in large community events (5.9% vs. 1.0%; P = 0.027) as well as in patients who reported COVID-19 related symptoms in the past six months. In addition, symptomatic VNT positive patients showed significantly higher (P = 0.031) NT antibody titers (median 128, interquartile range (IQR) = 32-128) compared to asymptomatic patients (median 16, IQR = 16-48).ConclusionsThis study showed that 15.6% of anti-SARS-CoV-2 ELISA positive Croatian SOTRs developed NT antibodies indicating protective immunity. Further studies are needed to determine the dynamic of NT antibodies and COVID-19 immunity duration in immunocompromised populations such as LTRs and KTRs.     

Diagnostic strategies for subclinical hypothyroidism

The aim of this study is to delineate laboratory diagnostic strategies for subclinical hypothyroidism in patients who are clinically symptomatic but may have a normal thyroid profile. Tri — iodothyronine (T₃), thyroxine (T₄), thyroid stimulating hormone (TSH) and anti thyroid peroxidase antibodies (anti-TPO) were estimated on fasting blood samples from 99 patients using electrochemiluminescence methods on ELECSYS 1010 (Roche). 74% of study subjects had elevated anti-TPO levels.61% patients had subclinical hypothyroidism. 45 of the 61 subclinical hypothyroid patients had elevated anti-TPO levels (73%). This is an important finding suggesting an autoimmune etiology for subclinical thyroid dysfunction with a higher risk of developing overt hypothyroidism.     

Diagnosis of gastrointestinal tuberculosis: Using cytomorphological,microbiological, immunological and molecular techniques — A study from Central India

The present study included three groups: (A) age and gender matched control (n=24) with no previous signs of M. tuberculosis complex (MTBC) infection, (B) patients (n=28) diagnosed with gastro-intestinal TB (GITB), (C) patients (n=50) with clinical and histo-pathological signs of GITB, but were culture and AFB negative. Real time assay performed using fluorescence resonance energy transfer hybridization probes showed a positivity index of 36 % in group C, i.e. 18 were found reactive from the total 50 cases studied. In addition, immune characterization of these 18 cases showed depleted CD₄⁺ count and increased levels of IFN-γ and TNF-α cytokines. No positive case was found in group A, while in group B, out of total 28 cases studied 27 were found positive. A combinatorial diagnostic approach for rapid detection and characterization of GITB might provide specific therapeutic strategies for prevention and treatment of the infection in future.     

聚合酶链反应检测乙型肝炎患者血清HBVDNA与ELISA检测HBeAg、抗HBe比较研究

应用聚合酶链反应（ＰＣＲ）检测了１５３例各型乙型肝炎患者的血清ＨＢＶＤＮＡ，并与ＥＬＩＳＡ法检测的血清ＨＢｅＡｇ和抗ＨＢｅ结果比较．结果ＨＢｅＡｇ阳性８９例，ＰＣＲ法ＨＢＶＤＮＡ检出率为９２．１３％；抗ＨＢｅ阳性２７例，ＰＣＲ法ＨＢＶＤＮＡ检出率为５１．８５％；ｅ系统用性３７例，ＰＣＲ法ＨＢＶＤＮＡ检出率为４０．５４％．提示抗ＨＢｅ血清学转换不能作为乙型肝炎病毒复制与非复制、病变活动与静止的唯一指标，而应该用或同时用ＨＢＶＤＮＡ作为指标才可靠．     

Evaluation of plasma hormone concentrations using Enzyme-Immunoassay/Enzyme-linked Immunosorbent assay in healthy Indian men: Effect of ethnicity

The study involved three ethnic groups of India; Rajputs, Gorkhas and South-Indians. Each group consisted of ∼40 healthy, male soldiers between 20–50 years. The reference ranges for cortisol, testosterone, prolactin, arginine vasopressin and proAtrial natriuretic peptide_1–98 were determined using Enzyme-Immunoassay (EIA) while plasma levels of thyroid-stimulating hormone, triiodothyronine, free-triiodothyronine, thyroxine and freethyroxine were measured using Enzyme-linked immunosorbent assay (ELISA). The results indicated that plasma hormone concentrations were within physiological range and inter-ethnic differences were most prominent between north- (Rajputs and Gorkhas) and south- Indians. In comparison to Radioimmunoassay, the EIA method for prolactin, thyroid-stimulating hormone, free-thyroxine gave higher values while the ELISA method for triiodothyronine, free-triiodothyronine, and thyroxine gave lower values. These differences are due to differences in assay standards and design.     

Serum PCT and its Relation to Body Weight Gain in Pulmonary Tuberculosis

The present study was aimed at assessing alterations in serum PCT in terms of its relation to body weight gain in pulmonary tuberculosis (PTB) patients undergoing treatment. Among patients (25–75 years) diagnosed with pulmonary tuberculosis, those that were new smear positive, showed sputum conversion at the end of 2 months and were declared clinically cured at the end of 6 months, were included in the study (n = 40). Serum procalcitonin was determined by BRAHMS PCT-Q kit. Patients were divided into two study groups—Group 1 (n = 21; serum PCT > 2 ng/ml at diagnosis), Group 2 (n = 19; serum PCT > 10 ng/ml at diagnosis). Body weights of all patients were obtained at three different time points, PTB-0 (at diagnosis), PTB-2 (after 2 months of intensive treatment) and PTB-6 (after 6 months of treatment). In both groups, mean body weights at PTB-2 and PTB-6 were significantly higher than those at PTB-0 and at PTB-6 were significantly higher than those at PTB-2. However, percentage body weight gain following 2 months of intensive treatment was higher in group 1 (4.05 % gain, p < 0.01) than in group 2 (2.75 % body weight gain, p < 0.05). Thus, the percentage gain in group 1 was tending more towards the desirable minimum gain of 5 % during intensive phase. Increase in serum PCT levels in pulmonary tuberculosis is inversely associated with body weight gain during treatment. Thus, PCT could play a role in regulation of body weight gain in anorectic conditions like tuberculosis.