ABSTRACT
Presence of antigen and antibodies in a sample may interfere with the antibody, as well as with antigen detection assays. In such a situation, avidity of the probing antigen or antibody plays the key role in the assay. In the present study, using monoclonal antibodies against a mycobacterial antigen, lipoarabinomannan, patient serum is depleted of mycobacterial antigen by capture immunoradiometric assay and this antigen-depleted serum is tested for anti-lipoarabinomannan antibodies by inhibition immunoradio-metric assay. It is observed that serum, after depletion of antigen, revealed enhanced antibody activity compared to initial levels. It, therefore, appears that the avidity of the probing monoclonal antibody may detach the antigen from the loosely attached complexes and renders the complexed antibody free, thus increasing the reactive antibody molecules in the serum.
Subject(s)
Antibodies, Bacterial/blood , Antigens, Bacterial/blood , Leprosy/immunology , Lipopolysaccharides/immunology , Antibodies, Bacterial/immunology , Humans , Immunoradiometric Assay , Leprosy/diagnosis , Lipopolysaccharides/blood , Mycobacterium leprae/immunologyABSTRACT
1. We have studied some generic and specific aspects of the humoral immune response in 96 patients with leprosy (29 paucibacillary and 67 multibacillary individuals). We determined serum immunoglobulins (IgM, IgG and IgA), CH50, C1q, C3 and C4, circulating immune complexes (CIC), C-reactive protein (CRP), rheumatoid factor (RF) and antinuclear antibodies. No specific pattern of general humoral immune changes could be observed. 2. The specific immune response was studied by the detection of specific IgM anti-M. leprae antibodies. An immunoradiometric assay (IRMA) and an ELISA were compared for clinical effectiveness. IRMA showed greater sensitivity for the serodiagnosis of leprosy as compared to ELISA (88.1 percent vs 58.2 percent for multibacillary patients and 20.7 percent vs 10.3 percent for paucibacillary leprosy patients). Specificity was 96 percent for IRMA and 97 percent for ELISA. 3. Our results indicate that nonspecific changes in the humoral immune response are of little value in assessing leprosy patients and that immune assays for the detection of specific anti-M. leprae antibodies may be of value in the diagnosis, study and follow-up of these patients
Subject(s)
Humans , Male , Female , Child , Adolescent , Adult , Middle Aged , Antibodies, Bacterial/analysis , Enzyme-Linked Immunosorbent Assay , Leprosy/immunology , Immunoradiometric Assay , Mycobacterium leprae/immunology , Antibodies, Antinuclear , C-Reactive Protein , Follow-Up Studies , Leprosy/diagnosis , Leprosy, Lepromatous/diagnosis , Leprosy, Lepromatous/immunology , Host-Parasite Interactions , Sensitivity and SpecificityABSTRACT
Tumor necrosis factor--alpha (TNF), one of the mediators of septic shock, has a role in the immunopathological complications of several infections. However, its role in leprosy is yet unclear. In this study, serum TNF and IL-1 levels in 64 patients spread over the spectrum of leprosy [lepromatous leprosy (LL), 30; borderline lepromatous, 12; borderline borderline, 8; and borderline tuberculoid-tuberculoid leprosy, 14] were measured at the time of admission. Elevated levels of TNF ranging from 15 to 4500 pg/ml were detected in lepromatous leprosy cases (399 +/- 189) and low levels ranging from 15 to 160 pg/ml were detected in the tuberculoid form of leprosy. Patients undergoing type 1 and type 2 lepra reactions also exhibited high TNF levels of 15-2100 pg/ml. Of the 14 clinically healthy individuals studied, 3 showed TNF levels of 15, 50, and 58 pg/ml. Interleukin 1-beta (IL-1) levels were found to be significantly higher in LL cases (70-5000 pg/ml) (328 +/- 184) in comparison to other groups or normal controls (9 +/- 3). The coefficient of correlation between TNF and IL-1 levels was statistically significant in LL and reaction cases (r = 0.96, P less than 0.001). These patients were followed up as outpatients for a period of 1 year. It was observed that 4 out of 8 patients with TNF levels greater than 100 pg/ml went into lepra reactions between 2 and 6 months after entry into the study, whereas only 5 out of 56 with less than 100 pg/ml went into mild lepra reactions (chi 2 = 9.7, P less than 0.01). Determination of TNF and IL-1 levels thus seems to have a prognostic significance in terms of lepra reaction in patients.
Subject(s)
Interleukin-1/blood , Leprosy/blood , Tumor Necrosis Factor-alpha/analysis , Adolescent , Adult , Aged , Child , Female , Humans , Immunoradiometric Assay , Lepromin/analysis , Leprosy, Borderline/blood , Leprosy, Lepromatous/blood , Leprosy, Tuberculoid/blood , Male , Middle AgedABSTRACT
An immunological technique for demonstration of Mycobacterium leprae antigen in sera was developed by using specific as well as cross-reactive monoclonal antibodies. The sandwich immunoradiometric assay which we developed is a simple, robust assay that is sensitive to the nanogram level. Sera from 72 leprosy patients were screened for the presence of antigen by this assay. A total of 69% of untreated tuberculoid leprosy patients showed 35-kDa antigen positivity, and 45% of these patients showed anti-35-kDa antibody positivity. Consistently higher antigen positivity rates for the 35-, 12-, and 30- to 40-kDa components of M. leprae were observed in lepromatous leprosy patients than in tuberculoid leprosy patients. During the course of therapy the antigen positivity rate gradually declined, and the antigen could not be detected in any of the 15 patients with subsided cases of leprosy. As antigen is presumably in excess before the antibody response is evoked, our experimental approach for antigen detection is likely to be useful by itself or along with antibody detection for diagnosis of early leprosy.