Thalidomide inhibited the synthesis of IgM and IgG whereas Thalidomide+Dexamethasone and Dexamethasone alone acted as co-stimulants with pokeweed and enhanced their synthesis

Thalidomide (Thal) provides effective treatment for erythema nodosum leprosum (ENL). In combination with Dexamethasome (Dex) it is an effective treatment for multiple myeloma (MM) and Waldenström's macroglobulinemia (WM). Thal's mechanism(s) of action in the treatment of these diverse medical conditions is not known, but it could be suppression of immunoglobulin (Ig) synthesis. Mononuclear cells were stimulated with pokeweed (PWM), and treated with Thal, Thal+Dex or Dex. The cultures were assayed for IgM and IgG. The maximum synthesis was expected to occur in cultures stimulated with PWM at 0.5, 5.0 or 10 microg/ml. The test agents at 15 microM each were expected to alter the response. Compared to cultures stimulated with PWM alone, there was significantly less Ig in the cultures containing Thal+PWM, and significantly more Ig in the cultures containing Thal+Dex+PWM or Dex+PWM (Wilcoxon). The median % of maximum was 57 for cultures treated with Thal+PWM; 184 for cultures treated with Thal+Dex+PWM, and 139 for cultures treated with Dex+PWM. Thal also acted as a co-stimulant with PWM and enhanced the synthesis of IL-2, IL-6 and DNA; whereas, Thal+Dex or Dex enhanced Ig synthesis, but suppressed IL-2, IL-6 and cell proliferation. Thal's ability to suppress Ig may explain its activity in ENL, MM and WM. The enhancement of Ig by Dex does not help to explain a role for Dex alone or in combination with Thal for the treatment of MM and WM.

Effect of thalidomide on the expression of TNF-alpha m-RNA and synthesis of TNF-alpha in cells from leprosy patients with reversal reaction

Hypersensitivity reactions called reversal reaction (RR) and erythema nodosum leprosum (ENL) occur in leprosy. They are characterized by an increase in tumor necrosis factor-alpha (TNF-alpha). Thalidomide is an effective treatment for ENL but not RR. Its effectiveness in ENL is attributed to inhibition of TNF-alpha, and this does not explain its failure to treat RR. We assessed thalidomide's effect on TNF-alpha in RR. Mononuclear cells from RR and non-RR patients and healthy individuals were treated with thalidomide and M.leprae (AFB), a cytosol fraction of M. leprae or Dharmendra lepromin. Thalidomide suppressed TNF-alpha, but when some RR patients' cells were stimulated with AFB, it enhanced TNF-alpha.

A geospatial risk assessment model for leprosy in Ethiopia based on environmental thermal-hydrological regime analysis

Geospatial methods were used to study the associations of the environmental thermal-hydrological regime with leprosy prevalence in the Oromia and Amhara regions of Ethiopia. Prediction models were developed that indicated leprosy prevalence was related to: (i) long-term normal climate grid data on temperature and moisture balance (rain/potential evapo-transpiration); (ii) satellite surveillance data on the Normalized Difference Vegetation Index (NDVI) and daytime earth surface temperature (Tmax) from the Advanced Very High Resolution Radiometer (AVHRR); and (iii) a Genetic Algorithm Rule-Set Prediction (GARP) model based on NDVI and Tmax data in relation to leprosy prevalence data. Our results suggest that vertical transmission is not the only means of acquiring leprosy and support earlier reports that a major factor that governs transmission of leprosy is the viability of Mycobacterium leprae outside the human body which is related to the thermal-hydrologic regime of the environment.

Effects of thalidomide on intracellular Mycobacterium leprae in normal and activated macrophages

Thalidomide is an effective drug for the treatment of erythema nodosum leprosum (ENL). ENL is an inflammatory reaction that may occur in multibacillary leprosy patients. Its cause(s) as well as the mechanism of thalidomide in arresting this condition are not fully understood. It has been suggested that ENL is an immune complex-mediated hypersensitivity precipitated by the release of Mycobacterium leprae from macrophages. The released antigen may complex with precipitating antibodies, initiating complement fixation and the production of inflammatory cytokines like tumor necrosis factor alpha (TNF-alpha). Thalidomide has been shown in vitro to reduce antigen- or mitogen-activated macrophage production of TNF-alpha. We investigated if thalidomide could also influence the viability of intracellular M. leprae. Mouse peritoneal macrophages were infected with M. leprae, activated with gamma interferon and endotoxin, or nonactivated, and treated with thalidomide. Intracellular bacilli were recovered, and metabolic activity was assessed by a radiorespirometric procedure. Thalidomide did not possess antimicrobial action against M. leprae in normal and activated host macrophages. This suggests that thalidomide does not retard the release of mycobacterial antigens, a possible prelude or precipitating factor for ENL. A distinct sequence of events explaining the mechanism of action for thalidomide's successful treatment of ENL has yet to be established.

Stabilization of red blood cell membranes by thalidomide in vitro

The anti-inflammatory effect of thalidomide has been well established. The mechanism of this anti-inflammatory action is still not completely understood. Certain drugs exert their anti-inflammatory action by stabilizing the membranes of polymorphonuclear neutrophils (PMN) thereby reducing the production of reactive oxygen intermediates. We evaluated the effect of thalidomide on cell membranes by using red blood cells (RBC), PMN and the monocyte-like cell line THP-1. Osmotic fragility of RBC showed that in vitro, thalidomide stabilized the membrane of RBC from plasma free blood; whereas, it did not affect RBCs from whole blood. Red blood cells taken from subjects before and after ingestion of thalidomide were not affected after exposure to different concentrations of hypotonic NaCl solution. Thalidomide did not affect the membrane stability of PMNs as well as THP-1 in a significant manner. These data suggest that the anti-inflammatory mechanism of thalidomide is not related to events associated with the oxidative burst of PMNs or monocytes.

Thalidomide does not modify the ability of cells in leprosy patients to incorporate [3H]-thymidine when incubated with M. leprae antigens

The immune response in reversal reaction, (RR) and in erythema nodosum leprosum (ENL) is characterized in vitro by an enhancement in lymphocyte blast transformation against M. leprae. As thalidomide is an effective treatment for ENL, this study assessed the effect of this drug on these phenomena. Mononuclear cells from patients attending the clinic at ALERT and from healthy staff were cultured for 5 days with integral M. leprae (IMl), or a modified Dharmendra antigen (Dhar), or PPD from M. tuberculosis. In one set of cultures, thalidomide was added once at the initiation of the culture; in the other set thalidomide was added a second time (2x), 18 h prior to harvesting the cells. The mononuclear cells, in the absence of thalidomide, from healthy staff, borderline tuberculoid patients (BT) and BT patients in RR (BT/RR) incorporated [3H]-thymidine best when cultured with PPD > Dhar > M. leprae. The cells from patients with ENL did not respond well to the M. leprae antigens. Thalidomide (2x) enhanced proliferation to Dhar in the BTRR group (Wilcoxon signed rank test, P < 0.05). No significant changes occurred for the other groups. Comparing PPD-stimulated cells treated with thalidomide once to those treated with thalidomide twice, thalidomide (2x) suppressed incorporation of [H3]-thymidine by the PPD-stimulated (P < 0.05) as well as IMl-stimulated (P < 0.05) cells in the healthy staff group. In the Dhar-stimulated cells from the healthy staff thalidomide significantly suppressed TNF-alpha (P < 0.05). A mixed effect was seen within and between the other groups, but there was a trend for thalidomide to suppress TNF-alpha induced by the M. leprae, Dhar and PPD antigens.

Randomized safety studies of intravenous perflubron emulsion. II. Effects on immune function in healthy volunteers

Particle size distribution is a major determinant of particle clearance by the mononuclear phagocytic system and the potential for concomitant activation of resident macrophages. To test the safety of a second-generation perflubron-based emulsion (60% perfluorocarbon [PFC] wt/vol; Oxygent [Alliance Pharmaceutical Corp., San Diego, CA]) with a small mean particle size, two parallel, randomized, double-blinded, placebo-controlled studies were conducted in 48 healthy volunteers (n = 24 per study). The study described herein focuses on safety concerning immune function. The primary endpoint was defined prospectively as delayed hypersensitivity skin test responses with lymphocyte proliferative responses to mitogenic stimulation providing a secondary measure for changes in cell-mediated immunity. Subjects received either perflubron emulsion IV (1.2 g PFC/kg or 1.8 g PFC/kg) or saline (3 mL/kg) control. Perflubron emulsion had no effect on delayed hypersensitivity skin reactions, lymphocyte proliferative potential, circulating immunoglobulins, complement activation, or plasma levels of the inflammatory cytokines, tumor necrosis factor-alpha, interleukin-1 alpha, and interleukin-1 beta. Perflubron emulsion was generally well tolerated, although there was a dose-dependent increase in minor flu-like symptoms in the perflubron treatment groups at 24 h after dosing. Increased serum levels of interleukin-6 were observed in those subjects exhibiting febrile responses. The clinical safety profile of perflubron emulsion supports its continued investigation as a temporary oxygen carrier in surgical patients to reduce exposure to allogeneic blood transfusion.

Effect of thalidomide on apoptosis of lymphocytes and neutrophils

Thalidomide causes congenital anomalies and it is immunomodulatory. These properties could be explained by an ability to alter the orderly process of programmed cell death during embryogenesis and modulation of apoptosis of lymphoid and/or myeloid cells in the immune response. Apoptosis of lymphoid and myeloid cells was studied by measuring the percentage of cells capable of excluding propidium iodide and expressing phosphatidylserine on their outer membrane. In addition, expression of Fc gamma RIII (CD16) was used to assess neutrophil apoptosis. Thalidomide did not affect the rate of apoptosis of CTLL-2 cells deprived of, or supplemented with, IL-2; of T-cells (mitogen-stimulated or resting) or of neutrophils. However, neutrophils obtained from HIV-infected patients treated with thalidomide showed reduced expression of CD16, a surrogate marker for apoptosis of neutrophils. Thalidomide's effect on neutrophil apoptosis in vivo warrants further investigation.

Hydrolysis of thalidomide abrogates its ability to enhance mononuclear cell synthesis of IL-2 as well as its ability to suppress the synthesis of TNF-alpha

Thalidomide is effective in the treatment of inflammatory conditions like erythema nodosum leprosum in leprosy patients, and aphthous ulcers in AIDS patients. Its mechanism of action is uncertain and reports of its effect on the synthesis of inflammatory cytokines such as IL-2 and TNF-alpha are contradictory. As thalidomide is labile to spontaneous hydrolysis at pH 7.4, studies were carried out to explore the effects of deliberate hydrolysis or the ability of thalidomide to modulated cytokine production by human mononuclear cells stimulated in vitro with Staphylococcal enterotoxin A (SEA)(IL-2) or lipopolysaccharide from Salmonella minnesota (LPS)(TNF-alpha). Unhydrolyzed thalidomide at 4.0 micrograms/ml consistently enhanced the synthesis of IL-2 in SEA-stimulated cells, and suppressed the synthesis of TNF-alpha in LPS-stimulated cells; whereas, hydrolyzed thalidomide had no enhancing effect on SEA stimulated-cell synthesis of IL-2 or suppressive effect on LPS stimulated-cell synthesis of TNF-alpha. These findings demonstrate that thalidomide's ability in vitro to enhance IL-2 and to suppress TNF-alpha in stimulated cells is dependent on the intact molecule and underscore the necessity to employ thalidomide under appropriate physicochemical conditions.

Immunomodulatory assays to study structure-activity relationships of thalidomide

Thalidomide, which has a long history of tragedy because of its ability to cause severe birth defects, is very effective in alleviating erythema nodosum leprosum in leprosy patients and aphthous ulcers in AIDS patients. The causes of these inflammatory diseases and the mechanism by which thalidomide diminishes them are unknown. It has been suggested that modulation of the immune response plays an important role. We found that thalidomide exerts immunomodulatory activity in three bioassays. It suppresses an IgM plaque forming cell response in mice injected with sheep erythrocytes: it inhibits TNF-alpha production by LPS stimulated human mononuclear cells: and it enhances IL-2 production by Con-A stimulated human mononuclear cells. We employed these bioassays to compare the activity of 15 analogs of thalidomide with thalidomide itself. Eight of the compounds were derivatives of the glutarimide moiety of thalidomide and the others were phthalimide or derivatives of the phthalimide moiety of thalidomide. N-hydroxyphthalimide, a simple derivative of phthalimide, was more effective than thalidomide and was also the most effective of the compounds assayed in suppressing the IgM plaque and TNF-alpha responses, but it did not enhance the IL-2 response, instead, it significantly suppressed it.

Thalidomide can be either agonistic or antagonistic to LPS evoked synthesis of TNF-alpha by mononuclear cells

The effect if thalidomide on tumor necrosis factor alpha (TNF-alpha) produced in vitro by lipopolysaccharide (LPS) stimulated human cells was investigated. In cultures of LPS stimulated human mononuclear cells enriched for adherent cells and in cultures of LPS stimulated human monocytes of the cell line-THP-1, thalidomide enhanced the synthesis of TNF-alpha. When cultures of unfractionated peripheral blood mononuclear cells were stimulated with LPS, thalidomide decreased the synthesis of TNF-alpha. Depending on the type of cells stimulated with LPS in vitro, thalidomide, at concentrations achieved in vivo, can either enhance or suppress the synthesis of TNF-alpha.

Thalidomide increases the synthesis of IL-2 in cultures of human mononuclear cells stimulated with Concanavalin-A, Staphylococcal enterotoxin A, and purified protein derivative

Thalidomide significantly increases the quantity of extracellular IL-2 in cultures of human mononuclear cells stimulated with mitogens or antigen. Cells from 7 donors exposed for 2 h to 4.0 micrograms/ml of thalidomide and stimulated for 16-18 h with 20 micrograms/ml of Concanavalin-A (Con-A) averaged producing 187 +/- 49% more IL-2 than cells stimulated with Con-A alone. In similar experimental procedures and comparisons the pg/ml of IL-2 secreted by thalidomide-treated cells from five donors stimulated with 50 ng/ml of Staphylococcal enterotoxin A (SEA) increased by 159 +/- 32%, and the pg/ml of IL-2 secreted by thalidomide-treated cells from 2 donors stimulated with 5.0 micrograms/ml of purified protein derivative of Mycobacterium tuberculosis increased by 120 +/- 4%. Thalidomide also significantly increases the quantity of intracellular IL-2 in cells stimulated with mitogens. Cells exposed to thalidomide and stimulated with Con-A had an increase in intracellular IL-2 of 130% after 8 h and 157% after 12 h in culture; cells stimulated with SEA had an increase in intracellular IL-2 of 120% after 8 h and 182% after 12 h in culture. Thalidomide did not alter the percent of lymphocytes expressing the alpha-chain of IL-2 receptor, nor did it significantly increase incorporation of [3H]thymidine by cells.

Analysis of T-cell and B-cell responses to recombinant M. leprae antigens in leprosy patients and in healthy contacts: significant T-cell responses to antigens in M. leprae nonresponders

The recognition of a panel of recombinant Mycobacterium leprae antigens by T cells and B cells from 29 borderline tuberculoid/tuberculoid (BT/TT) and 18 lepromatous leprosy (LL) patients and from 21 healthy controls (HC) in leprosy-endemic regions of Ethiopia was examined. All 11 antigenic molecules tested (including M. leprae hsp 10, hsp18, hsp65 and several novel M. leprae antigens) were shown to be recognized by T cells, but clear quantitative differences existed between reactivities induced by individual antigens. Similar quantitative differences were observed when antibody responses to hsp10 and hsp65 antigens were determined. No associations were found between the antigen-specific responses and the subject status of either BT/TT and LL patients or HC. Fifteen percent of the patients who were nonresponsive to sonicates of M. leprae showed significant T-cell responses to one or more individual M. leprae antigens. This indicates that M. leprae constituents other than the proteins tested are responsible for the M. leprae-specific nonresponsiveness in these patients, which may be exploited for the design of vaccines or immunotherapeutic modalities aimed at inducing M. leprae-specific immunity in nonresponders.

Early detection of rifampin in human nerve tissue after an oral dose of 600 milligrams

Rifampin in picogram quantities inhibited the ability of Mycobacterium bovis 44 BCG P3 to release 14CO2 from the oxidation of [14C]palmitic acid. By using these mycobacteria in a bioassay, samples of serum and posterior tibial nerve were assayed for inhibitory concentrations of rifampin. Within 8 to 12 h after ingestion of 600 mg of rifampin, the drug was detected in eight patients in concentrations ranging from 0.52 to 4.1 micrograms/ml in serum and in concentrations ranging from 0.6 to 6.3 ng/mg in posterior tibial nerve fiber tissue.

Thalidomide does not perturb CD2, CD4, CD5, CD8, HLA-DR, or HLA-A, B, C molecules in vitro on the membranes of cells with immune potential

Thalidomide dramatically relieves the signs and symptoms of erythema nodosum leprosum (ENL). ENL is an acute inflammatory complication of lepromatous leprosy. The cause(s) of ENL as well as the mechanism of action of thalidomide in arresting ENL are unknowns. It has been suggested that ENL is the consequence of a transient activation of a cell-mediated-immune (CMI) response to Mycobacterium leprae. To initiate a CMI response, an interaction between adhesion and/or signal transducing molecules on T-cells and molecules on antigen presenting cells would occur. An alteration, induced by thalidomide, of one or more of the molecules on T-cells or antigen presenting cells that are essential to maintaining the reactive state of ENL, could explain Thalidomide's ability to attenuate ENL. Thalidomide did not modify: (a) adhesion and/or signal transducing molecules such as CD2, CD4, CD5 and CD8, or (b) molecules that facilitate antigen presentation such as HLA-DR, HLA-A, HLA-B, or HLA-C.

Titration of numbers of human-derived Mycobacterium leprae required to progressively oxidize 14C-palmitic acid and release 14CO2

Mycobacterium leprae was isolated from skin-punch biopsies of 2 untreated lepromatous leprosy patients. The bacteria were enumerated, diluted 10-fold and cultured in Middlebrook 7H9 medium supplemented with albumin, dextrose, catalase and 14C-palmitic acid. The cultures were incubated at 33 degrees C in a modified Buddemeyer radiorespiratory detection vessel. Those cultures containing at least 10(7) mycobacteria demonstrated a progressive evolution of 14CO2.

Lepromin responses in recipients of a candidate antileprosy bacterin vaccine (WHO-IMMLEP Mycobacterium leprae killed preparation) in the USA

BACKGROUND

Identification of the nine-banded armadillo as a potential source of massive numbers of Mycobacterium leprae led to the development of a candidate bacterin vaccine for possible immunoprophylaxis.

METHODS

Volunteers were from a leprosy-hypoendemic, nonBCG-using area (USA). They had been vaccinated intradermally 3 years earlier with a candidate antileprosy bacterin vaccine of irradiated and autoclaved Mycobacterium leprae obtained from experimental nine-banded armadillos. They were tested for dermal responsiveness to standard lepromin A.

RESULTS

Values for induration and erythema appeared slightly greater for the vaccinated group; however, the differences were not statistically significant, indicating no appreciable 'anamnestic' effect on either Fernandez (early) or Mitsuda (late) reactions after 3 years.

CONCLUSIONS

Because previous studies had demonstrated that administration of this bacterin produced no humoral changes, it now appears less probable that laboratory methods will be of much help in assessing even possible effectiveness of such vaccination.

Competency of human-derived Mycobacterium leprae to use palmitic acid in the synthesis of phenolic glycolipid-I and phthiocerol dimycocerosate and to release CO2 in axenic culture

Insufficient numbers of viable Mycobacterium leprae have hampered metabolic studies using human-derived M. leprae. In this study, sufficient numbers of M. leprae were obtained from an untreated lepromatous patient to titrate the effects of pH on the metabolism of 14C-palmitic acid by M. leprae. Catabolic metabolism (oxidation of 14C-palmitic acid and release of 14CO2) was maximal when M. leprae were incubated at 33 degrees C and suspended in Middlebrook 7H9, ADC supplemented medium that had been buffered to maintain a pH of 4.8. Anabolic metabolism (synthesis of 14C-phenolic glycolipid-I and its precursor, 14C-phthiocerol dimycocerosate) was maximal when the pH was maintained at 6.8.

Thalidomide's effectiveness in erythema nodosum leprosum is associated with a decrease in CD4+ cells in the peripheral blood

Thalidomide is well documented as being an effective drug in the treatment of erythema nodosum leprosum (ENL). The mechanism of action of thalidomide in ENL as well as the pathogenesis of ENL are yet to be fully determined. Lepromatous leprosy patients experiencing ENL have been reported to have an increase in the ratio of CD4+ to CD8+ cells in their blood and ENL skin lesions. Thalidomide has been shown to cause a decrease in the ratio of CD4+ to CD8+ lymphocytes in the blood of healthy males. This decrease was due to a significant reduction in the numbers of Cd4+ lymphocytes and an apparent increase in the numbers of CD8+ lymphocytes. In this study, thalidomide's effectiveness in halting chronic ENL and arresting a relapse into ENL was consistently associated with a decrease in the numbers of CD4+ lymphocytes in the blood of 2 male lepromatous leprosy patients.

The evolution of antibody response in armadillos inoculated with Mycobacterium leprae

Plasma from 30 armadillos (Dasypus novemcinctus) was collected prior to inoculation and at approximately 3-month intervals for a period of 1-3 years. These animals were inoculated intravenously with 6.1 x 10(8) +/- 2 x 10(8) (x +/- SD) armadillo-derived Mycobacterium leprae. These samples were analysed for antibodies of IgM and IgG class to phenolic glycolipid-I (PGL-I) and to sonicated M. leprae components using ELISA and immunoblotting techniques, respectively. We had previously observed among a group of 11 armadillos, that some animals produced and maintained a high IgG antibody response to PGL-I. In this study, an animal's ability to produce and maintain an elevated IgG anti-PGL-I response was significantly correlated with their ability to delay dissemination of the infection and their ability to survive longer. When the animals were moribund, a significant decrease in the IgG anti-PGL-I absorbance value was observed. The detection of PGL-I in the plasma samples collected from moribund armadillos suggested that high concentrations of PGL-I in the plasma may have contributed to a drop in absorbance values by the formation of non-lattice-type immune complexes in vivo. As detected by immunoblotting, the IgM and IgG response to antigens derived from sonically disrupted M. leprae was directed towards molecules with broad bands of immunoreactivity ranging from 21- to 45-kDa. There were no distinguishing features of these antibody responses among armadillos as was evident with the IgG anti-PGL-I responses.

Confirmation of a false-positive result associated with a competition inhibition assay used for detecting antibodies to a protein epitope of Mycobacterium leprae

A competitive antibody-binding assay (CABA) was developed to detect antibodies in infected armadillos and leprosy patients which compete with an M. leprae-specific 125I monoclonal antibody IIIE9 for the species-specific M. leprae-IIIE9 epitope on the 65-kD protein. The results suggest armadillos and leprosy patients produce antibodies that inhibit the binding of 125I-IIIE9 monoclonal antibody to the IIIE9 epitope on crude, native 65-kD protein preparations. When purified, recombinant 65-kD protein was substituted for crude antigen, there was no evidence in the CABA of antibody to the IIIE9 epitope. False-positive results, possibly induced by steric hindrance, are likely to be associated with CABA which incorporate crude cell wall extracts as solid-phase antigen.

Armadillo IgG and IgM antibody responses to phenolic glycolipid-I during experimental infection with M. leprae

The kinetics of antibody responses of Mycobacterium leprae-infected armadillos to phenolic glycolipid-I (PGL-I) were studied by means of ELISA. The levels of both IgG and IgM antibodies to PGL-I increased with time. Some animals were less susceptible to disseminations of M. leprae infection and lived longer than others. These animals had high absorbance values (greater than 0.7) for IgG anti-PGL-I compared to more susceptible armadillos that had lower absorbance values for IgG anti-PGL-I.

Partial characterization of antigens from M. leprae evoking IgG and IgM antibodies in armadillos

Armadillo IgG and IgM antibody responses to Mycobacterium leprae were analyzed using isotypic-specific antisera by means of immunoblotting. Blots developed for IgG antibodies to M. leprae showed multiple protein antigens (Mr = 12-90 K) in some heavily infected armadillos. In contrast, blots developed for IgM antibodies to M. leprae showed a single, broad, diffuse band of immunoreactivity at approximately 33 kDa. The 33-kDa immunogen was detectable with silver stain modified for carbohydrate reactivity, suggesting the presence of a polysaccharide component. In addition, binding of 125I-concanavalin A to the 33-kDa component demonstrated the presence of mannose and/or glucose residues.

Adoptively transferred reactivity to M. leprae in nude mice infected with M. leprae

Reversal reactions are manifestations of delayed hypersensitivity to M. leprae and are thought to be usually accompanied by manifestations of effective cell-mediated immunity (CMI) as measured by bacterial clearing. These experiments were designed to study the induction of reversal reactions in M. leprae-infected, congenitally athymic nude mice using adoptive transfer of CMI. Splenic cell suspensions derived from unimmunized heterozygous nu/+ mice, and those vaccinated with heat-killed M. leprae, viable BCG and a mixture of the two antigens were diluted to contain 10(4), 10(5), 10(6), 10(7) lymphocytes/0.1 ml and infused intravenously into multibacillary nude mice. The production of reversal reactions in leprous nude mice in response to adoptively transferred CMI was studied in a quantitative fashion. Dose responsive induction of reversal reactions, apparent by footpad inflammation and swelling, decreased morphological indices (MI) of the bacteria and mononuclear cell infiltrations, histopathologically, were observed. For nude mice receiving cells primed with 3.9 X 10(5) living BCG alone, the effective dose 50% (ED50) was 1.0 x 10(6) lymphocytes to induce reversal reactions. For those receiving cells primed with 10(7) M. leprae the ED50 was 3.7 x 10(5) lymphocytes. For nude mice receiving cells primed with a mixture consisting of 1/2 the above dose of BCG + 1/2 the above dose of M. leprae, the ED50 was 6.8 x 10(4) lymphocytes.

Evaluation of monitoring antibodies to PGL-I in armadillos experimentally infected with M. leprae

An enzyme-linked immunosorbent assay (ELISA) for IgM antibodies to the phenolic glycolipid-I antigen of Mycobacterium leprae was evaluated for efficacy in monitoring armadillos experimentally infected with the bacillus. IgM antibodies were detected in armadillos from 186 days after experimental infection until the animals were sacrificed. The ELISA demonstrated the establishment of infection earlier and more reliably than the histologic methods previously applied. Satisfactory yields of M. leprae from individual armadillos could be predicted 97% of the time, and the technique may be useful in identifying appropriate harvest times or resistance among armadillos. The ELISA seems to be a valuable adjunct for managing experimental infections of M. leprae in armadillos.

Evaluation of the origin of Mycobacterium leprae infections in the wild armadillo, Dasypus novemcinctus

An enzyme-linked immunosorbent assay (ELISA) using the phenolic glycolipid-1 (PGL-1) antigen of Mycobacterium leprae and cross-reactive antisera specific for human IgM was developed to detect IgM antibodies to M. leprae in the nine-banded armadillo (Dasypus novemcinctus). Statistical definitions for positive and negative interpretations in the ELISA were developed by screening animals recently captured and experimentally inoculated with M. leprae. The ELISA was shown to have high sensitivity and specificity. Modern day armadillos of central Louisiana were observed to have a PGL-1 antibody prevalence rate as high as 20%, and a clinical disease rate as high as 5%. A retrospective serological survey of 182 armadillos taken in the years 1960-1964 and predating the use of armadillos in leprosy research was used to evaluate the 1968 environmental contamination hypothesis for the origin of M. leprae infections in the wild armadillo. Antibodies to the apparently species-specific PGL-1 antigen were detected in 17 of the samples taken in 1960-1964. Absorption with whole M. leprae, M. intracellulare, M. terrae, M. rhodesiae, M. scrofulaceum, M. diernhoferi, M. kansasii, M. phlei, M. avium, BCG, and 2 new armadillo-derived mycobacterial species showed these antibody reactions to be specific for PGL-1. Apparently, M. leprae was enzootic in armadillos as early as 1961, and original infection of these animals could not have occurred in 1968.

Inhibition of de novo IgM antibody synthesis by thalidomide as a relevant mechanism of action in leprosy

Thalidomide is well documented to be an effective treatment for erythema nodosum leprosum (ENL) occurring in lepromatous leprosy. To be beneficial, thalidomide must interfere with one or more of the several essential steps in the pathogenesis of this syndrome, which is presumed to be a clinical manifestation of an Arthur-type hypersensitivity. Since complexes of antigen and antibody would initiate these events, thalidomide could exert its most direct influence on reactants in this essential step. To determine whether thalidomide affected de novo antibody synthesis, the effect of the drug on the antibody response to sheep erythrocytes in mice was determined. Thalidomide significantly inhibited IgM antibody formation when fed to mice for 5 or 7 days before immunization with sheep erythrocytes. There was also a selective decrease in serum IgM concentrations among leprosy patients being treated with thalidomide for ENL. A clinically relevant site of action of thalidomide in ENL appears to be on the synthesis of IgM antibody. The target site of the drug among the macrophage, antibody-forming, and helper or suppressor lymphocytes remains to be elucidated.

Methods for the identification of human B lymphocytes

Complement-receptor lymphocytes and monocytes were identified by a rosette method using trypsin treated sheep erythrocytes (Et), sensitized with affinity column purified IgM (19S) antibodies against sheep erythrocytes (E) and mouse complement deficient in C5. Fc receptor mononuclear cells were identified by a rosette method using Et and IgG (7S) antibodies against E. Identification of the cell-type rosetting was facilitated by myeloperoxidase staining of dry mounted rosetted preparations. Comparison of lymphocytes with receptors for activated mouse complement and lymphocytes with stable surface immunoglobulin detected by immunofluorescent assay, strongly suggests that these cells constitute the same population in the peripheral blood of healthy humans.