Th1-specific bystander costimulation imparts resistance against Mycobacterium tuberculosis infection

The protection against Mycobacterium tuberculosis infection is mediated by T helper type-1 (Th1) cells. Infection of BALB/c mice with M. tuberculosis downregulates expression of a Th1-specific costimulatory molecule, M150, on the surface of infected macrophages. The proliferation of Th cells and Th1-cytokine production by these cells are higher in case of M. tuberculosis antigen presentation by uninfected macrophages than by infected macrophages. The difference in inducing interleukin(IL)-2 and interferon (IFN)-gamma secretion is abolished by providing bystander costimulation through M150 on liposomes.

Efficacy of single-dose ROM therapy plus low-dose convit vaccine as an adjuvant for treatment of paucibacillary leprosy patients with a single skin lesion

The recent World Health Organization multicentric field study on the treatment of paucibacillary (PB) leprosy patients with single skin lesion (SSL) and a single dose of rifampin-ofloxacin-minocycline (ROM) brought new hope to those who are engaged in the eradication of leprosy from India. Being encouraged by the WHO report, we undertook the present hospital-based study and found that PB leprosy patients with SSL were morphologically and histopathologically heterogeneous. The histological spectrum of SSL ranged from indeterminate through tuberculoid (TT) to borderline tuberculoid (BT) leprosy, and most patients had active BT leprosy. Ninety new, untreated PB leprosy patients with SSL were included in the present study for comparative assessment of the efficacies of ROM and ROM plus Convit vaccine therapies. Children, pregnant women, lactating mothers and patients with any thickening of nerves were excluded. All patients were bacteriologically negative (skin-smear test) but lepromin reactive. The patients were divided into two groups after proper matching for morphological and histological status of SSL: a) The test group included 60 patients and the control group included 30 patients. The test group was given a single dose of ROM initially and two injections of low-dose Convit vaccine, one initially and the other at the end of 3 months. b) The control group was given only a single dose of ROM initially. Both groups were followed clinically every 2 weeks for 6 months and retested for histological, bacteriological and lepromin status at the end of 6 months. Thereafter, they were followed clinically every month for another 6 months. In the test group, the SSL resolved in 33.3%, regressed in 48.3%, and remained active in 18.3% of the patients, while the granuloma disappeared in 70% of the cases. Only one patient developed neuritis, and in another patient the disease relapsed on the eighth month. On the other hand, the SSL in the control patients resolved, regressed and remained active in 13.3%, 63.3% and 23.3% of the cases, respectively, while the granuloma disappeared in 53.3% of the cases. In the seven patients who remained active, the disease course was progressive, and two of them developed neuritis. The clinical outcome of the patients treated with ROM plus low-dose Convit vaccine was statistically superior to those treated with single-dose ROM therapy alone.

Conductometric determination of carbon in uranium carbide and its solution in nitric acid

A simple but accurate method has been developed for the determination of carbon in uranium carbide powders/pellets as well as in solutions of uranyl nitrates. The methodology involves quantitative conversion of carbon present in the sample to carbon dioxide that is subsequently absorbed in a dilute solution of barium hydroxide. The conductivity shift of the barium hydroxide solution is monitored on-line continuously using a laboratory-built PC-based conductivity measurement system that has been developed in-house based on the direct conversion of conductance to the digital pulse frequency. A new gas absorption cell has been designed to ensure quantitative absorption during the residence time of the gas in the cell. The method is sensitive, accurate and precise to 1-3% at 600-1000 mug of carbon in samples of uranium carbide.

Antinociceptive effects of tetrahydrocannabinol side chain analogs: dependence upon route of administration

The role of flexibility of the alkyl side chain in the tetrahydrocannabinols to cannabinoid activity has been delineated in previous studies with side chain analogs of Delta(8)-tetrahydrocannabinol with double or triple bonds. This study investigated the site of antinociceptive action for these analogs through analysis of structure-activity relationships following different routes of administration. In analogs without terminal substitutions, potency was greater following intrathecal (i. t.) injection than with intracerebroventricular (i.c.v.). Further, optimal structural features differed for each route of administration. Absolute position of the double or triple bond best predicted i.t. potency. In contrast, i.c.v. potency was best predicted by the size of the alkyl substituent beyond the point of unsaturation. Terminal substitutions tended to increase i.c.v. potency while decreasing or not affecting i.t. These results suggest that receptor mechanisms for cannabinoid antinociceptive effects differ in brain and spinal cord, although potential pharmacokinetic differences in rate of local distribution cannot be eliminated.

Material equations for electromagnetism with toroidal polarizations

With regard to the toroid contributions, a modified system of equations of electrodynamics moving continuous media has been obtained. Alternative formalisms to introduce the toroid moment contributions in the equations of electromagnetism has been worked out. The two four-potential formalism has been developed. Lorentz transformation laws for the toroid polarizations has been given. Covariant form of equations of electrodynamics of continuous media with toroid polarizations has been written.

O-1057, a potent water-soluble cannabinoid receptor agonist with antinociceptive properties

Cannabinoids have low water solubility, necessitating the use of a solubilizing agent. In this paper we investigated whether a novel water-soluble cannabinoid, 3-(5'-cyano-1', 1'-dimethylpentyl)-1-(4-N-morpholinobutyryloxy)-Delta(8)- tetrahydroca nnabinol hydrochloride (O-1057), would interact with cannabinoid receptors when water or saline were used as the only vehicle. O-1057 displaced [(3)H]-CP55940 from specific binding sites on Chinese hamster ovary (CHO) cell membranes expressing CB(1) or CB(2) cannabinoid receptors, with pK(i) values of 8.36 and 7.95 respectively. It also displaced [(3)H]-CP55940 from specific binding sites on rat brain membranes (pK(i) = 7.86). O-1057 inhibited forskolin-stimulated cyclic AMP production by both CB(1)- and CB(2)-transfected CHO cells (pEC(50) = 9.16 and 9.72 respectively), its potency matching that of CP55940 and exceeding that of Delta(9)-tetrahydrocannabinol. In the mouse isolated vas deferens, O-1057 inhibited electrically-evoked contractions with pEC(50) and E(max) values of 9.73 and 76.84% respectively. It was antagonized by 100 nM SR141716A, the pK(B) of SR141716A against O-1057 (8.90) approximating to that against CP55940 (8.97). O-1057 also behaved as a CB(1) receptor agonist in vivo, reducing mouse spontaneous activity and rectal temperature when injected intravenously and inducing antinociception in the mouse tail flick test when given intravenously (ED(50) = 0.02 mg kg(-1)), intrathecally, intracerebroventricularly or by gavage. In all these assays, O-1057 was more potent than Delta(9)-tetrahydrocannabinol and, at 0.1 mg kg(-1) i.v., was antagonized by SR141716A (3 mg kg(-1) i.v.). These data demonstrate the ability of the water-soluble cannabinoid, O-1057, to act as a potent agonist at CB(1) and CB(2) receptors and warrant investigation of the clinical potential of O-1057 as an analgesic.

Thermal and photochemical reduction of aqueous chlorine by ruthenium(II) polypyridyl complexes

Studies are reported on the reactions of aqueous chlorine with a series of substitution-inert, one-electron metal-complex reductants, which includes [Ru(bpy)3]2+, [Ru(4,4'-Me2bpy)3]2+, [Ru(4,7-Me2phen)3]2+, [Ru(terpy)2]2+, and [Fe(3,4,7,8-Me4phen)3]2+. The reactions were studied by spectrophotometry at 25 degrees C in acidic chloride media at mu = 0.3 M. In general the reactions have the stoichiometry 2[ML3]2+ + Cl2-->2[ML3]3+ + 2Cl-. In the case of [Ru(bpy)3]2+, the reaction is quite photosensitive; the thermal reaction is so slow as to be practically immeasurable. The reactions of [Ru(4,4'-Me2bpy)3]2+ and [Ru(4,7-Me2phen)3]2+ are also highly photosensitive, giving pseudo-first-order rate constants that depend on the monochromator slit width in a stopped-flow instrument; however, the thermal rates are fast enough that they can be obtained by extrapolation of kobs to zero slit width. The reactions of [Ru(terpy)2]2+ and [Fe(3,4,7,8-Me4phen)3]2+ show no appreciable photosensitivity, allowing direct determination of their thermal rate laws. From the kinetic effects of pH, [Cl2]tot, and [Cl-] it is evident that all of the thermal rate laws have a first-order dependence on [ML3]2+ and on [Cl2]. The second-order rate constants decrease as Eo for the complex increases, consistent with the predictions of Marcus theory for an outer-sphere electron-transfer mechanism. Quantum yields at 460 nm for the reactions of [Ru(4,4'-Me2bpy)3]2+ and [Ru(4,7-Me2phen)3]2+ exceed 0.1 and show a dependence on [Cl2] indicative of competition among spontaneous decay of *Ru, nonreactive quenching by Cl2, and reactive quenching by Cl2.

Recent trends in leprosy in a large district of West Bengal, India, revealed by a modified leprosy elimination campaign (MLEC), 1998

A Modified Leprosy Elimination Campaign (MLEC) in September 1998 in the District of Midnapore, West Bengal, covered a population of 8.1 million people and detected 8181 new cases. Available data from 7328 cases were studied to observe the trend for leprosy in this area. Data are presented on sex and age distribution, classification and the proportions of multibacillary (MB), paucibacillary (PB) and single skin lesion (SSL) cases discovered in a period of only 8 days. The large numbers of people examined in this district and the high total of new cases revealed are in keeping with experience in other parts of the State and in other parts of India. However, many cases were found in endemic areas and these will receive special attention in a second MLEC, planned for January 2000.

Manipulation of the tetrahydrocannabinol side chain delineates agonists, partial agonists, and antagonists

Structure-activity relation studies have established that the alkyl side chain in tetrahydrocannabinol (THC) plays a crucial role in the activation of the cannabinoid receptor. Unfortunately, the flexible nature of this side chain has hampered efforts to elucidate the precise nature of the interaction of THC with its receptors. Therefore, a series of analogs with structurally restrained side chains of varying length was synthesized and evaluated for pharmacological potency in mice and for receptor affinity. The introduction of cis double bonds inserted rigid angles, whereas triple bonds developed regions of planarity. Receptor affinity for the acetylenic and saturated side chains were the same, whereas double bond substitution increased affinity 10-fold. Moreover, the relationship between receptor affinity and potency was 10-fold less than that of Delta(8)-THC in the case of some acetylenic derivatives, whereas changing the triple bond to a double bond restored the potency/affinity ratio. Additionally, an acetylene at C2-C3 in the octyl and nonyl side chains favored antinociception by as much as 70-fold. Surprisingly, several high-affinity acetylenic derivatives, especially those with cyano substitutions at the terminus of the side chain, were partial agonists or were inactive. Some of these low-efficacy, high-affinity ligands elicited antagonistic activity. The finding that manipulations of the side chain produces high- affinity ligands with either antagonist, partial agonist, or full agonist effects reveals a critical structural feature for receptor activation.

Susceptibility or resistance to Leishmania infection is dictated by the macrophages evolved under the influence of IL-3 or GM-CSF

Although enhanced monocytopoiesis is a hallmark of leishmaniasis, its significance in determining the course of the disease has not been addressed. While the number of granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting cells increases in the draining lymph nodes in a resistant mouse strain (C57BL/6) during disease, in a susceptible strain (BALB/c) the number of interleukin-3 (IL-3)-secreting cells increases. Treatment of BALB/c mice with anti-IL-3 antibody significantly reduces the disease score. Bone marrow macrophages derived under stimulation with IL-3 (IL-3-Mphi) or GM-CSF (GM-Mphi) differ functionally. GM-Mphi are significantly more responsive to IFN-gamma-induced augmentation and more refractory to IL-4-mediated suppression of anti-leishmanial activity than IL-3-Mphi. LPS-induced IL-12 and TNF-alpha secretion by both the susceptible and resistant strain-derived macrophage subsets are down-regulated. Despite down-regulation of IL-12 secretion, GM-Mphi favor expansion of IFN-gamma-secreting cells and IL-3-Mphi favor IL-6-dependent expansion of the IL-4-secreting Th subset. Adoptive transfer of leishmanial antigen-pulsed IL-3-Mphi and GM-Mphi prior to infection either aggravated or reduced the disease score, respectively, in BALB/c mice. Anti-IL-6 treatment reverted the Th subset profile not only in vitro but also in vivo, resulting in a reduced disease score in both infected BALB/c mice and IL-3-Mphi recipients. The disease score in IL-3-Mphi recipients is also reduced significantly after anti-IL-4 treatment.

An investigation into the structural determinants of cannabinoid receptor ligand efficacy

1. A number of side-chain analogues of delta8-THC were tested in GTPgammaS binding assay in rat cerebellar membranes. O-1125, a saturated side-chain compound stimulated GTPgammaS binding with an Emax of 165.0%, and an EC50 of 17.4 nM. 2. O-1236, O-1237 and O-1238, three-enyl derivatives containing a cis carbon-carbon double bond in the side-chain, stimulated GTPgammaS binding, acting as partial agonists with Emax values ranging from 51.3-87.5% and EC50 values between 4.4 and 29.7 nM. 3. The stimulatory effects of O-1125, O-1236, O-1237 and O-1238 on GTPgammaS binding were antagonized by the CB1 receptor antagonist SR 141716A. The K(B) values obtained ranged from 0.11-0.21 mM, suggesting an action at CB1 receptors. 4. Five-ynyl derivatives (O-584, O-806, O-823, O-1176 and O-1184), each containing a carbon-carbon triple bond in the side-chain, did not stimulate GTPgammaS binding and were tested as potential cannabinoid receptor antagonists. 5. Each -ynyl compound antagonized the stimulatory effects of four cannabinoid receptor agonists on GTPgammaS binding. The K(B) values obtained, all found to be in the nanomolar range, did not differ between agonists or from cerebellar binding affinity. 6. In conclusion, alterations of the side-chain of the classical cannabinoid structure may exert a large influence on affinity and efficacy at the CB1 receptor. 7. Furthermore, this study confirms the ability of the GTPgammaS binding assay to assess discrete differences in ligand efficacies which potentially may not be observed using alternative functional assays, thus providing a unique tool for the assessment of the molecular mechanisms underlying ligand efficacies.

Leishmania donovani infection of a susceptible host results in CD4+ T-cell apoptosis and decreased Th1 cytokine production

The disease visceral leishmaniasis is caused by a protozoan parasite, Leishmania donovani and is characterized by depressed cell-mediated immunity (CMI) and unhindered parasite growth in a susceptible host. The opposite trend is observed in a resistant host. However, the mechanism of this loss of CMI during the progressive disease is unknown as yet. In this report, we demonstrate that more than 40% of CD4+ T cells from a susceptible host undergo apoptosis resulting in a significant decrease in interleukin (IL)-2 and interferon (IFN)-gamma secretion, leaving IL-4 secretion unaffected. These changes are not apparent in the case of CD4+ T cells derived from a resistant host. The data reported here suggest that experimental Leishmania donovani infection leads to selective deletion of the IL-2 and IFN-gamma-secreting cells but not Th2-like cells in a susceptible but not a resistant host.

Apoptosis of Th1-like cells in experimental tuberculosis (TB)

Th1 cell-induced anti-mycobacterial immunity is lost during a progressive Mycobacterium tuberculosis infection in a susceptible host. This study was designed to test the mechanism of the loss of anti-mycobacterial cell-mediated immune response. We demonstrate that M. tuberculosis infection results in increased Fas expression and decreased Bcl-2 expression in CD4+ T cells. When CD4+ T cells are stimulated in vitro, they show increased apoptosis and decreased production of IL-2 and interferon-gamma (IFN-gamma) but not of IL-4. These changes may result in selective apoptosis of Th1-like cells, leading to the loss of cell-mediated immune response against M. tuberculosis.

Leishmania donovani infection of a susceptible host results in apoptosis of Th1-like cells: rescue of anti-leishmanial CMI by providing Th1-specific bystander costimulation

A protective immune response against Leishmania donovani infection is mediated by T-helper type 1 (Th1) cells. Th1 induced cell-mediated immunity (CMI), as assessed by anti-leishmanial DTH response, is lost in a susceptible host such as BALB/c mice. Although the impaired Th1 function eventuates in unhindered parasite growth and in manifestation of the susceptible phenotype, the mechanism of down-regulation of the Th1 function is yet to be elucidated. Here, we provide evidence that the parasite down-regulates the expression of a Th1-specific costimulatory molecule, M150, on the surface of infected BALB/c mice-derived macrophages. Th cells are rendered unresponsive to anti-CD3 Ab-mediated stimulation after interaction with infected macrophages. The anergized T cells produce much less IL-2, IL-4 and IFN-gamma compared to those T cells which were costimulated using normal macrophages. The defect in proliferation, anti-CD3 Ab induced unresponsiveness and IFN-gamma but not IL-4 production can be restored by providing bystander costimulation through M150. These results not only unfold a novel immune evasion strategy used by the parasite but also clarify the mechanism of Th1 cell debilitation during the disease. Recovery of Th1 cytokine production by bystander costimulation through M150 may help in formulating a new strategy for the elimination of intracellular parasites.

Association of vitamin D receptor genotype with leprosy type

Host genetic factors including major histocompatibility complex (MHC) polymorphisms influence both susceptibility to leprosy per se and also to leprosy type. Non-MHC genes may play an important role, but such genes remain undefined. The influence of two non-MHC candidate genes was assessed in a case-control study of Bengali leprosy patients from Calcutta. Recent studies have implicated variation in the vitamin D receptor (VDR) gene in susceptibility to several diseases, including osteoporosis and pulmonary tuberculosis. In this population, homozygotes for the alternate alleles of the VDR polymorphism are associated, respectively, with lepromatous and tuberculoid leprosy. The NRAMP1 (natural resistance associated macrophage protein 1) gene may influence human mycobacterial disease susceptibility based on studies with the murine homologue Nramp1. However, no significant association was found between NRAMP1 and leprosy susceptibility. This study suggests that the VDR polymorphism may influence susceptibility to some diseases by affecting the type and the strength of the host immune response.

CTLA4 (CD152) modulates the Th subset response and alters the course of experimental Leishmania major infection

Since both the nature and the amplitude of an antigen-specific T cell response are dependent on co-stimulatory signals, we have investigated the role of CD28/CD152-mediated T cell co-stimulation in the regulation of experimental cutaneous leishmaniasis. CD28-deficient mice and their wild-type littermates are equally susceptible to Leishmania major infection. Whole anti-CD152 antibody significantly exacerbates the disease while anti-CD152 Fab ameliorates the disease in genetically susceptible BALB/c mice but not in C57BL/6, a resistant strain. The anti-CD152-induced exacerbation of the disease is accompanied by increased IL-4-secreting cell number, diminished parasite-specific delayed-type hypersensitivity (DTH) response and augmented anti-2,4,6-trinitrophenyl (TNP) IgG1 in response to TNP-leishmanial antigen crude soluble antigen (CSA), suggesting an exaggerated Th2 type of response. Anti-CD152 Fab-mediated amelioration of the disease is associated with increased IFN-gamma-secreting cell number, increased parasite-specific DTH response and enhanced IgG2a isotype in response to TNP-CSA suggesting a Th1 type of response. Unlike TNP-CSA, TNP-keyhole limpet hemocyanin does not induce the change in Ig isotype, indicating that the immunomodulatory effect of anti-CD152 is antigen specific. Anti-CD152 antibody-induced early change in Th subsets suggests an important role for CD152 in determining the course of L. major infection, perhaps by alteration of Th subset differentiation.

Comparison of cannabinoid binding sites in guinea-pig forebrain and small intestine

We have investigated the nature of cannabinoid receptors in guinea-pig small intestine by establishing whether this tissue contains cannabinoid receptors with similar binding properties to those of brain CB1 receptors. The cannabinoids used were the CB1-selective antagonist SR141716A, the CB2-selective antagonist SR144528, the novel cannabinoid receptor ligand, 6'-azidohex-2'-yne-delta8-tetrahydrocannabinol (O-1184), and the agonists CP55940, which binds equally well to CB1 and CB2 receptors, and WIN55212-2, which shows marginal CB2 selectivity. [3H]-CP55940 (1 nM) underwent extensive specific binding both to forebrain membranes (76.3%) and to membranes obtained by sucrose density gradient fractionation of homogenates of myenteric plexus-longitudinal muscle of guinea-pig small intestine (65.2%). Its binding capacity (Bmax) was higher in forebrain (4281 fmol mg(-1)) than in intestinal membranes (2092 fmol mg(-1)). However, the corresponding KD values were not significantly different from each other (2.29 and 1.75 nM respectively). Nor did the Ki values for its displacement by CP55940, WIN55212-2, O-1184, SR141716A and SR144528 from forebrain membranes (0.87, 4.15, 2.85, 5.32 and 371.9 respectively) differ significantly from the corresponding Ki values determined in experiments with intestinal membranes (0.99, 5.03, 3.16, 4.95 and 361.5 nM respectively). The Bmax values of [3H]-CP55940 and [3H]-SR141716A in forebrain membranes did not differ significantly from each other (4281 and 5658 fmol mg(-1)) but were both greater than the Bmax of [3H]-WIN55212-2 (2032 fmol mg(-1)). O-1184 (10 or 100 nM) produced parallel dextral shifts in the log concentration-response curves of WIN55212-2 and CP55940 for inhibition of electrically-evoked contractions of the myenteric plexus-longitudinal muscle preparation, its KD values being 0.20 nM (against WIN55212-2) and 0.89 nM (against CP55940). We conclude that cannabinoid binding sites in guinea-pig small intestine closely resemble CB1 binding sites of guinea-pig brain and that 0-1184 behaves as a cannabinoid receptor antagonist in the guinea-pig myenteric plexus-longitudinal muscle preparation.

Potent cyano and carboxamido side-chain analogues of 1', 1'-dimethyl-delta8-tetrahydrocannabinol

The synthesis and pharmacological profile of several cyano (1a-e) and carboxamido (2a-h) side-chain-substituted analogues of 1', 1'-dimethyl-Delta8-THC are described. Commercially available cyano compound 3 was transformed to the resorcinol 6 in a three-step sequence. Condensation of 6 with p-menth-2-ene-1,8-diol formed the THC 7a which, with sodium cyanide/DMSO, gave 1b. Protection of the phenol in 7a as the MOM derivative provided the common intermediate 8 for the synthesis of 1a,c,e. Compound 1d was also synthesized from 7a via the aldehyde 9a. Base hydrolysis of 1b gave the acid 10 which, via its acid chloride and subsequent treatment with the appropriate amine, formed the target compounds 2a-h. The pharmacological profile indicated that the cyano analogues 1a-e had very high CB1 binding affinity (0.36-13 nM) and high in vivo potency as agonists. Two analogues (1a,b) had extremely high potency in the mouse tetrad tests. The dimethylcarboxamido analogue 2a showed a similar profile to 1a,b. The high potency was also retained in analogue 2c. In contrast the sulfonamide analogue 2d was unique as it had greater affinity than Delta9-THC, yet it was practically devoid of agonist effects. This study suggests that the incorporation of a cyano or an amide substituent in the side chain of Delta8-THC-DMH can enhance potency and can also lead to compounds with a unique profile which have high binding affinity and are practically devoid of agonist effects.

Altered membrane permeability as the basis of bactericidal action of methdilazine

The growth inhibition of Escherichia coli and Staphylococcus aureus was accompanied by significant release of K+ and UV-absorbing small molecules upon exposure to methdilazine, an extensively used phenothiazine antihistamine. A severe decrease in [U-14C] glucose uptake and a rapid efflux of hexose from sugar-preloaded bacteria were also observed but without visible cellular lysis. Considerable damage to membrane permeability by methdilazine was proposed to explain the rapid loss in cfu/mL of the bacteria.

Why relapse occurs in PB leprosy patients after adequate MDT despite they are Mitsuda reactive: lessons form Convit's experiment on bacteria-clearing capacity of lepromin-induced granuloma

It is amazing how after years of scientific research and therapeutic progress many simple and basic questions about protective immunity against Mycobacterium leprae remain unanswered. Although the World Health Organization (WHO) has recommended short-term multidrug therapy (WHO/MDT) for the treatment of paucibacillary (PB) leprosy patients, from time to time several workers from different parts of the globe have reported inadequate clinical responses in a few tuberculoid and indeterminate leprosy patients following adequate WHO/MDT despite the fact that they are Mitsuda responsive. A few borderline tuberculoid patients harbor acid-fast bacilli (AFB) in their nerves for many years even though they become clinically inactive following MDT, a fact which has been ignored by many leprosy field workers. Keeping these patients in mind, we have attempted to investigate the cause of the persistence of AFB in PB cases and have looked into the question of why Mitsuda positivity in tuberculoid and indeterminate leprosy patients, as well as in healthy contacts, is not invariably a guarantee for protectivity against the leprosy bacilli. We have: a) analyzed the histological features of lepromin-induced granulomas, b) studied the bacteria-clearing capacity of the macrophages within such granulomas, and c) studied the in vitro leukocyte migration inhibition factor released by the blood leukocytes of these subjects when M. leprae sonicates have been used as an elicitor. The results of these three tests in the three groups of subjects have been compared and led us to conclude that the bacteria-clearing capacity of the macrophages within lepromin-induced granuloma (positive CCB test) may be taken as an indicator of the capability of elimination of leprosy bacilli and protective immunity against the disease. This important macrophage function is not invariably present in all tuberculoid and indeterminate leprosy patients or in all contacts even though they are Mitsuda responsive and are able to show a positive leukocyte migration inhibition (LMI) test. It is likely but not certain that this deficit of the macrophage is genetically predetermined and persists after completion of short-term WHO/MDT. Thus, after discontinuation of treatment slow-growing, persisting M. leprae multiply within macrophages leading to relapse.

Tumor necrosis factor promoter polymorphism and susceptibility to lepromatous leprosy

Genetically determined differences in immune responses to environmental agents may underlie susceptibility to many autoimmune and infectious diseases. Leprosy provides an example of a polarity in the type of immune response made to an infectious agent, and there is evidence that the major histocompatibility complex is genetically linked to leprosy type. It was found that HLA-DR2 is associated with both tuberculoid and lepromatous types of leprosy; however, a variant at position -308 of the promoter of the neighboring tumor necrosis factor (TNF) gene was increased in frequency in lepromatous (odds ratio = 3.0, P = .02) but not tuberculoid leprosy. Some studies have found higher serum levels of TNF in lepromatous than tuberculoid leprosy, and high TNF levels are found in malaria and leishmaniasis, which are also associated with this TNF allele. It is speculated that this association reflects genetic variability in cytokine production, which influences the immune response to and clinical outcome of leprosy.