Seroreactivity of 31 kDa and 41 kDa mycobacterial secretory proteins isolated from culture filtrate in extra pulmonary tuberculosis.

Despite rapid advances in molecular genetics for detection of mycobacteria, it is clear that interest in serodiagnosis remains high, especially for those situations in which a specimen may not contain the infecting agent in particular in extrapulmonary tuberculosis. Immune response to excretory-secretory (ES) proteins of Mycobacterium tuberculosis (M.tb) has been of diagnostic interest in tuberculosis. In earlier study from our laboratory, a secretory protein M.tb ES-31 has been shown to have diagnostic potential in pulmonary tuberculosis. Further, another M.tb H37Ra ES protein (ES-41) was isolated and purified by trichloroacetic acid solubilization followed by Fast Performance Liquid Chromatography (FPLC). These two protein fractions viz ES-31 and ES-41 secreted by M.tb H37 Ra bacilli were employed in stick indirect penicillinase ELISA to study seroreactivity in extra pulmonary tuberculosis namely tuberculous lymphadenopathy, tuberculous meningitis, abdominal tuberculosis and bone & joint tuberculosis. While using ES-31 antigen 88% (22/25) of tuberculous lymphadenopathy and 90% (9/10) of tuberculous meningitis cases showed positive reaction for tuberculous IgG antibody, ES-41 showed 80% positivity in both groups. In abdominal and bone & joint tuberculosis cases, ES-41 antigen showed better sensitivity of 81.5% (22/27) and 84.6% (22/26) respectively in IgG antibody detection compared to 70% (19/27) and 69.2% (18/26) shown by ES-31. This study is of interest that different antigen protein fractions of M.tb exhibit differential seroreactivity, as ES-31 protein showed good potential in detecting tuberculous IgG antibodies in tuberculous lymphadenopathy (TBLN) & tuberculous meningitis (TBM), while ES-41 in abdominal and bone & joint tuberculosis cases.

A simple screening test for the detection of heterozygous beta thalassemia.

Beta-Thalassemia is prevalent in a high frequency of 5-15% in selected geographical areas and ethnic communities. There is need to screen large populations for the heterozygotes of beta-Thalassemia. We have evaluated NESTROFT (Naked eye single tube red cell osmotic fragility test) with 0.36% buffered saline in this study. Of the population screened, 42 cases were positive with NESTROFT, of which 40 were positive with the confirmatory test for beta-Thalassemia. This implies a positive predictive value and specificity of 100%, negative predictive value of 83.3% and sensitivity of 95.2%.

Cytodiagnosis of discharge per vaginum.

Simple, rapid, inexpensive methods such as pH determination, wet mount, KOH mount, amine test, Gram staining of vaginal discharge were undertaken prior to Pap stained smears of 158 patients of leucorrhoea. We were able to detect non-specific vaginitis (44.30%), Trichomoniasis (16.45%), Candida vaginitis (9.49%), gonococcal vaginitis (0.63%) and senile vaginitis (12 cases). No specific pathology was shown in 26 cases. 1.69% of the cases were of cervical erosion and 3.79% cases suggestive of squamous malignancy.

Immunochemical studies in multiple myeloma.

The study deals with a total of 72 patients with Plasma cell dyscrasias (PCD) selected on the basis of atypical plasmacytosis in the bone marrow aspirate and radiological evidence of osteolytic lesions. Males(48) outnumbered the females (24). Pathological fracture and paraplegia was the commonest presenting symptom encountered in 38 patients. Electrophoresis of serum for 'M' band and Immunoelectrophoretic analysis of the serum revealed IgG myeloma in 40 patients followed by, IgA myeloma(13), Light chain disease (12) and other variants in remaining seven cases. The urinary Bence Jones proteins were detected in a total of 34 cases and was frequently encountered with IgA myeloma (7 out of 13) compared with IgG myeloma (13 out of 40) when analysed in Disc electrophoresis. Kappa light chain was observed in 21 cases and lambda counterpart in nine cases without any clinical significance. One case of solitary myeloma terminated in characteristic multicentric multiple myelomatosis within a span of six months in the sequential follow up study. We recommend the triangular approach to diagnosis of paraproteinemia with a special emphasis on immunoelectrophoresis for typing multiple myeloma and allied disorders along with disc electrophoresis for the demonstration of urinary Bence Jones protein in the routine set up.

Bisalbuminemia: an interesting electrophoretic abnormality--a report of two cases.

We hereby report two cases of Bisalbuminemia for its extreme rarity in Indian literature. In an attempt to look for 'M' component, polyacrylamide gel disc electrophoresis of serum displayed observation. The saline eluates of the slower (variant in our cases) and the faster component showed a reaction of complete identify in the agar gel double diffusion test when tested against monospecific antialbumin antibody. The immunoelectrophoretic analysis also confirmed the antigenic similarity between the two fractions. A wider use of disc electrophoresis perhaps would disclose additional cases of Bisalbuminemia in normals and in disease states.

Sequential study of IgG antibody response in immunized rabbit and development of immunization protocol for raising monospecific antibody.

The present study was planned to develop an immunization protocol to decide the bleeding modalities for harvesting anti IgG antibody from the immunized rabbit. A fourteen dose immunization protocol (four primary and ten boosters) of the purified human IgG spread over the one calendar year was executed. The antibody titre estimated by Reverse Single Radial Immunodiffusion displayed a six-phased pattern. The titre following the initial immunization ranged between nil to 1.02, characteristic of the primary response while the titres after 7th and 8th boosters (phase V) ranged between 0.5 to 3.87 consistent with secondary response. Phase II, III, IV had moderately elevated titres. The antibody titre amongst the six phases reached to its peak generally by the 12th day after the last dose of protocol and it took about 60 days to reach to its basal level. Administration of antigen with the higher levels of residual antibody did not produce high titre antibody and is probably ascribed to elimination of antigen through an immunecomplex mechanism. Based on the data we recommend that 15 batches. (3 per phase, phase I to phase V) with a total yield of 100 to 120 ml of serum can be procured from one immunised animal over the span of one calendar year and that should make the programme cost effective.

Reverse single radial immunodiffusion for estimation of titre of anti IgG antibody.

Reverse Single Radial Immunodiffusion (SRID) for estimating titre of anti IgG antisera is reported. Unlike the conventional radial immunodiffusion, the antigen (IgG) is held immobile in the gel while the antibody (Anti IgG) diffuses radially from the well (7 microliters) and the diameter of the resulting immuneprecipitates after immunodiffusion at 4 degrees C for 24 hr, represents a linear correlation with the antibody titre. The procedure was standardised by an extensive trial and error employing different concentrations of human IgG in the gel (60-240 micrograms) against varying dilutions of the standard antibody (titre: 3.8 mg/ml). The best results were obtained at 80 micrograms of IgG in the gel. The locally raised rabbit anti IgG antisera displayed a distinctive titre pattern under optimised conditions. Technical reproducibility, high-sensitivity threshold (0.25 mg/ml), simultaneous visual scrutiny of several antibody batches at a glance and ability to assess the shelf life of the stored antisera are its distinct assets.