Effective Cell-mediated Immune Response Research Articles

Fusion protein Ag85B-MPT64 190–198-Mtb8.4 has higher immunogenicity than Ag85B with capacity to boost BCG-primed immunity against Mycobacterium tuberculosis in mice

Tuberculosis (TB) remains a major infectious disease worldwide despite chemotherapy and BCG vaccine. The efficacy of the current TB vaccine BCG varies from 0 to 80%. New vaccines that have better protection than BCG or have the capability to boost BCG-primed immunity are urgently needed. We have previously constructed a fusion protein Ag85B-MPT64 190–198-Mtb8.4 (AMM). In this study, we investigated the immunogenicity of the fusion protein AMM in a novel adjuvant of dimethyl-dioctyldecyl ammonium bromide and BCG polysaccharide nucleic acid (DDA–BCG PSN), and its capacity to boost BCG-primed immunity. The anti-Ag85B antibodies IgG1 and IgG2a were determined using ELISA and the number of spleen cells secreting IFN-γ was determined by ELISPOT. In addition, the ability of the subunit vaccine AMM to boost BCG-primed immunity against Mycobacterium tuberculosis was analyzed. The fusion protein AMM induced more effective humoral and cell-mediated immune responses in mice than Ag85B alone. Mice primed with BCG vaccination followed by boosting with AMM produced a stronger immune response and afforded a better protection against M. tuberculosis infection than mice immunized with BCG alone or BCG priming followed by boosting with Ag85B. These findings suggest that AMM is a promising candidate subunit vaccine to enhance the protective efficiency of BCG.

Vaccination with Leukemia Cell Expression Membrane Bound GM-CSF Overcomes the Host Immunosuppression Induced by Leukemia

Immunotherapy of leukemia involves stimulating host-cell mediated immunity by facilitating immune recognition of leukemia cells, which are normally weakly immunogenic. We previously showed that vaccination with membrane bound GM-CSF leukemic cells protects mice from leukemia challenge (Ling et al., Oncogene, 2007). In these studies, after addition of a transmembrane domain to the original GM-CSF coding sequence (tmGM-CSF), the construct was transduced into murine leukemia cells (WEHI-3B), which was shown to be more than 98% on the cell surface. Vaccination with lethally irradiated tmGM-CSF expressing murine leukemia cells prevents leukemia in immunocompetent mice (BALB/c), as 100% of vaccinated BALB/c mice were protected from leukemia (Ling et al, Oncogene 2007). No protection was observed by vaccination of nude mice, indicating that adaptive immunity is involved in the protective response. In the present studies, we extended our original observation and provided evidence to show that leukemic mice undergo immunosuppression and that vaccination with leukemia cells expressing cell surface tmGM-CSF overcomes immunosuppression. Vaccination with lethally irradiated leukemia cells expressing cell surface tmGM-CSF overcame the immunosuppression induced by leukemia development, as normal levels of CD4+/CD25+/Foxp3+ T-regulatory (Treg) cells were maintained in spleens and thymus after challenge with leukemia cells. In contrast, the Treg population was significantly increased in leukemic mice vaccinated with leukemia cells lacking cell surface tmGM-CSF (p<0.001) after leukemia challenge, and these mice had a lower CD8+/Treg cell ratio (p<0.01). The ratio of CD8+/Treg cells was higher in tmGM-CSF/GFP vaccinated mice than in GFP vaccinated mice (p<0.001), which in-turn leads to a more effective CD8+ T-cell response. DC levels were also increased from normal levels in mice vaccinated with tmGM-CSF+ leukemia cells compared to control vaccinations. These results suggest that vaccination with leukemia cells expressing GM-CSF on their cell surface leads to an effective cell-mediated immune response in the vaccinated host by overcoming an impaired host cellular immunity induced up-regulation of Treg cells caused by the leukemia process. This strategy has potential for use in the treatment of various human leukemias.

Ex vivo recovery and activation of dysfunctional, anergic, monocyte-derived dendritic cells from patients with operable breast cancer: critical role of IFN-alpha

BackgroundDendritic cells (DCs) play a crucial role in initiating effective cell-mediated immune responses, but are dysfunctional and anergic in breast cancer. Reversal of this dysfunction and establishment of optimal DC function is a key prerequisite for the induction of effective anti-cancer immune responses.ResultsPeripheral blood DCs (PBDCs) and lymph node DCs (LNDCs) generated in vitro from adherent cultures of peripheral blood monocytes (PBMs) and lymph node monocytes (LNMs), respectively, using the 4 cytokine conditioned medium (CCM) (GM-CSF+IL-4+TNF-α+IFN-α) or 3 CCM (GM-CSF+IL-4+TNF-α) demonstrated a significantly higher degree of recovery and functional capacity in a mixed lymphocyte DC reaction (MLDCR, p < 0.001), expressed significantly higher levels of HLA-DR, CD86, compared with 2 CCM (GM-CSF+IL-4) or medium alone generated DCs from PBMs and LNMs (p < 0.001). The PBDCs generated with 3 CCM or 4 CCM showed a significantly (p < 0.001) enhanced macropinocytotic capability (dextran particles) and induced increased production and secretion of interleukin-12p40 (IL-12p40) in vitro (p < 0.001), compared with PBDCs generated from monocytes using 2 CCM or medium alone. Lipopolysaccharide (LPS) stimulation of PBDCs generated with 4 CCM demonstrated enhanced secretion of IL-6 but not IL-12p70, compared with control DCs unstimulated with LPS (p < 0.001).ConclusionDysfunctional and anergic PBDCs and LNDCs from patients with operable breast cancer can be optimally reversed by ex vivo culturing of precursor adherent monocytes using a 4 CCM containing IFN-α. Maximal immunophenotypic recovery and functional reactivation of DCs is seen in the presence of IFN-α. However, 4 CCM containing IFN-α generated-PBDCs, do not produce and secrete IL-12p70 in vitro.

Epidemiologic analysis of histologic cervical inflammation: relationship to human papillomavirus infections

Infections with carcinogenic human papillomaviruses, the causal agents of cervical intraepithelial neoplasia and cancer, as well as infections with noncarcinogenic human papillomaviruses, are common but typically resolve spontaneously. Effective cell-mediated immune responses are critical for human papillomavirus clearance; however, data relating cervical inflammation to the outcome of human papillomavirus infection are lacking. To investigate this topic, we performed a masked parallel review of inflammation in the stroma and epithelium of cervical biopsies (n = 564) collected from a retrospectively defined subcohort of women systematically followed up in the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study. Women in our analysis had undergone colposcopically directed enrollment biopsies diagnosed as negative or cervical intraepithelial neoplasia 1 and had corresponding human papillomavirus polymerase chain reaction test results of negative (n = 250), positive for a single carcinogenic (n = 237), or noncarcinogenic (n = 81) type. Inflammation in cervical stroma varied with cofactors for human papillomavirus progression: current smokers showed less inflammation (odds ratio, 0.55; 95% confidence interval, 0.31-0.97), whereas current oral contraceptive users had increased inflammation (odds ratio, 1.7; 95% confidence interval, 0.92-3.0) as did those with a self-reported 2-year history of a sexually transmitted disease (odds ratio, 1.9; 95% confidence interval, 1.0-3.5). Biopsies of women with carcinogenic human papillomaviruses had greater inflammation within the epithelium (odds ratio, 1.6; 95% confidence interval, 1.1-2.3) compared with human papillomavirus-negative women. Associations with human papillomavirus type-specific persistence or progression to histologic cervical intraepithelial neoplasia 3 were diminished among women with moderate or marked inflammation in stroma (odds ratio, 0.49; 95% confidence interval, 0.25-0.99) or within epithelium (odds ratio, 0.51; 95% confidence interval, 0.26-0.97). These data suggest that cervical inflammation varies with human papillomavirus cofactors, type of human papillomavirus infection, and risk of persistence and progression. Additional studies are needed to confirm and extend these findings.

Nitric Oxide: Friendly Rivalry in Tuberculosis

Immune dependent growth and development of infectious agents and pathogenesis are increasingly being recognized as crucial for designing efficient immunotherapeutic approaches for Mycobacterium tuberculosis. Nitric oxide (NO) in the context of mycobacterial infection is an essential component of the protective armory of host innate immune system. However, the ability of NO to suppress host immune response questions the traditional view that production of NO is actually designed for anti-microbial mechanism. Human tuberculosis is considered as a prime example of a disease controlled dominantly by cell-mediated and not by humoral immunity. Interleukins like IL-12 and IL-8 play important roles in anti-tuberculosis immunity. While IL-8 has a central role in leukocyte recruitment to areas of granuloma formation, IL-12 helps in the generation of effective cell-mediated immune response in tuberculosis. NO shows an ability to inhibit mycobacterial infection by inducing innate-cytotoxic response and by increasing IL-8 induction. However, it may become a problem in later phase when it converts a protective Th1 response to a subversive Th2 response mainly by inhibiting IL-12 cytokine, thus acting as a potential regulator of Th1/Th2 response. This review intends to explore the possibilities that can be envisioned for exploring NO from immunotherapeutic perspectives in mycobacterial immunity.

Expression of rabbit IL-4 by recombinant myxoma viruses enhances virulence and overcomes genetic resistance to myxomatosis

Rabbit IL-4 was expressed in the virulent standard laboratory strain (SLS) and the attenuated Uriarra (Ur) strain of myxoma virus with the aim of creating a Th2 cytokine environment and inhibiting the development of an antiviral cell-mediated response to myxomatosis in infected rabbits. This allowed testing of a model for genetic resistance to myxomatosis in wild rabbits that have undergone 50 years of natural selection for resistance to myxomatosis. Expression of IL-4 significantly enhanced virulence of both virulent and attenuated virus strains in susceptible (laboratory) and resistant (wild) rabbits. SLS-IL-4 completely overcame genetic resistance in wild rabbits. The pathogenesis of SLS-IL-4 was compared in susceptible and resistant rabbits. The results support a model for resistance to myxomatosis of an enhanced innate immune response controlling virus replication and allowing an effective antiviral cell-mediated immune response to develop in resistant rabbits. Expression of IL-4 did not overcome immunity to myxomatosis induced by immunization.

Hepatology highlights

Hepatology highlights

IL-10 down-regulates T cell activation by antigen-presenting liver sinusoidal endothelial cells through decreased antigen uptake via the mannose receptor and lowered surface expression of accessory molecules.

Our study demonstrates that antigen-presenting liver sinusoidal endothelial cells (LSEC) induce production of interferon-gamma (IFN-gamma) from cloned Th1 CD4+ T cells. We show that LSEC used the mannose receptor for antigen uptake, which further strengthened the role of LSEC as antigen-presenting cell (APC) population in the liver. The ability of LSEC to activate cloned CD4+ T cells antigen-specifically was down-regulated by exogenous prostaglandin E2 (PGE2) and by IL-10. We identify two separate mechanisms by which IL-10 down-regulated T cell activation through LSEC. IL-10 decreased the constitutive surface expression of MHC class II as well as of the accessory molecules CD80 and CD86 on LSEC. Furthermore, IL-10 diminished mannose receptor activity in LSEC. Decreased antigen uptake via the mannose receptor and decreased expression of accessory molecules may explain the down-regulation of T cell activation through IL-10. Importantly, the expression of low numbers of antigen on MHC II in the absence of accessory signals on LSEC may lead to induction of anergy in T cells. Because PGE2 and IL-10 are released from LSEC or Kupffer cells (KC) in response to those concentrations of endotoxin found physiologically in portal venous blood, it is possible that the continuous presence of these mediators and their negative effect on the local APC may explain the inability of the liver to induce T cell activation and to clear chronic infections. Our results support the notion that antigen presentation by LSEC in the hepatic microenvironment contributes to the observed inability to mount an effective cell-mediated immune response in the liver.

Regulation of CD40L expression on natural killer cells by interleukin-12 and interferon gamma: its role in the elicitation of an effective antitumor immune response.

Effector cell functions are regulated by a number of positive signals for the mediation of antitumor immunity. The CD40 and CD40 ligand (CD40L) interaction has been implicated in the generation of effective cell-mediated and humoral immune responses, where cytokines have been shown to play a significant role in the expression of these molecules. Our earlier studies have shown that spontaneous regression of a rat histiocytoma transplanted s.c. is mediated by CD8 + CD3- NK cells. The CD40-CD40L mediation during tumor regression was of interest. Tumor-transplanted animals showed enhanced expression of CD40L on natural killer (NK) and T cells, when compared to cells from normal animals. CD40 expression on AK-5 tumor cells was also induced after s.c. transplantation. Administration of anti-(interleukin-12) (anti-IL-12) and anti-(interferon gamma) (anti-IFNgamma) antibodies in tumor-bearing animals showed down-regulation of the expression of CD40L on NK and T cells with simultaneous inhibition of cytotoxic acitivity of NK cells, cytokine release and the production of antitumor antibody. Naive NK cells, when co-cultured with fixed AK-5 cells, were induced to express CD40L. CD40L expression modulated the immune response exerted by NK cells, in part by the activation of nuclear factor kB (NF-kB). Furthermore, the signaling via CD40L through the use of anti-CD40L antibody promoted the in vitro activation of cytotoxic as well as NF-kappaB binding activity in NK cells from tumor-transplanted animals. These observations demonstrate that the expression of CD40L by the effector cells is regulated by IL-12 and IFNgamma, and could effectively modulate the NK-cell-mediated immune response during the regression of AK-5 tumor.

IL-10–producing T cells suppress immune responses in anergic tuberculosis patients

The lethality of Mycobacterium tuberculosis remains the highest among infectious organisms and is linked to inadequate immune response of the host. Containment and cure of tuberculosis requires an effective cell-mediated immune response, and the absence, during active tuberculosis infection, of delayed-type hypersensitivity (DTH) responses to mycobacterial antigens, defined as anergy, is associated with poor clinical outcome. To investigate the biochemical events associated with this anergy, we screened 206 patients with pulmonary tuberculosis and identified anergic patients by their lack of dermal reactivity to tuberculin purified protein derivative (PPD). In vitro stimulation of T cells with PPD induced production of IL-10, IFN-gamma, and proliferation in PPD(+) patients, whereas cells from anergic patients produced IL-10 but not IFN-gamma and failed to proliferate in response to this treatment. Moreover, in anergic patients IL-10-producing T cells were constitutively present, and T-cell receptor-mediated (TCR-mediated) stimulation resulted in defective phosphorylation of TCRzeta and defective activation of ZAP-70 and MAPK. These results show that T-cell anergy can be induced by antigen in vivo in the intact human host and provide new insights into mechanisms by which M. tuberculosis escapes immune surveillance.

Host susceptibility factors to cutaneous leishmaniasis.

The host-pathogen relationship is the focus of many different studies which use a variety of disease models and different pathogens. Immunological studies in the mouse using the intracellular parasite Leishmania have helped define several aspects of host-pathogen interactions. Resistance to Leishmania is dependent on the development of CD4+ Th1 cells which promote an effective cell mediated immune response. Production of the cytokine IFN-gamma during this immune response activates macrophages enabling them to kill the parasite and control the infection. In contrast, susceptibility to this parasite is characterized by a Th2 response which produces predominantly IL-4. This cytokine promotes high antibody titers directed towards the parasite but does not activate macrophages for parasite killing. This host response results in high parasite numbers and a progressive increase in lesion size. The mouse model of leishmaniasis has been extremely useful in gaining an understanding of the immunological factors important in determining T cell commitment into Th1 or Th2 populations during an in vivo immune response.

The tumor necrosis factor alpha-stimulating region of galactose-inhibitable lectin of Entamoeba histolytica activates gamma interferon-primed macrophages for amebicidal activity mediated by nitric oxide

Entamoeba histolytica adheres via galactose-lectin (Gal-lectin) to human colonic mucins and intestinal epithelial cells as a prerequisite to amebic invasion. Native Gal-lectin is a protective antigen in the gerbil model of amebiasis. Amino acids 596 to 1082 of Gal-lectin mediate E. histolytica adherence to target cells and stimulate tumor necrosis factor alpha (TNF-alpha) production by naive murine bone marrow macrophages (BMM). Resistance to amebiasis requires an effective cell-mediated immune response against E. histolytica trophozoites mediated by nitric oxide (NO) released from activated macrophages. Herein, we determine whether the TNF-alpha-stimulating region of Gal-lectin can activate gamma interferon (IFN-gamma)-primed BMM for NO production and amebicidal activity. Native Gal-lectin (100 to 500 ng/ml) stimulated TNF-alpha and inducible nitric oxide synthase (iNOS) mRNA expression in IFN-gamma-primed BMM as did lipopolysaccharide (100 ng/ml). Primed BMM produced TNF-alpha and NO in response to Gal-lectin in a dose-dependent manner. Antilectin monoclonal antibody IG7, which recognizes a domain (amino acids 596 to 818) of the TNF-alpha mRNA-stimulating region of Gal-lectin, specifically inhibited TNF-alpha and iNOS mRNA induction and TNF-alpha and NO production by primed BMM in response to Gal-lectin (100 ng/ml). Simultaneous treatment of BMM with IFN-gamma and Gal-lectin (100 ng/ml) activated the cells to kill E. histolytica trophozoites, whereas IFN-gamma treatment alone had no effect. In the presence of monoclonal antibody 1G7 or aminoguanidine (an iNOS inhibitor), NO production and amebicidal activity were inhibited >80%. These results suggest that the TNF-alpha-stimulating region of native Gal-lectin is a potent stimulus of IFN-gamma-primed BMM for NO production, which is essential for host defense against amebiasis.

Delivery Systems for Immunomodulatory Proteins and Peptides

Polypeptide and protein immunomodulators are subject to absorption, biodistribution, metabolism and degradation at sites and rates which may not permit effective interactions with components of the immune system. Drug carrier technology can overcome some of these obstacles. Because of the lipid and particulate nature of liposomes, increased delivery of immunomodulators to lymphatics, lymph nodes, lymphatic organs and concentrations of macrophages is possible when an immunomodulator is associated with a liposome. Interleukin-2 (IL-2) liposomes have been shown to have less toxicity and increased immunotherapeutic effects in a number of model systems and are currently in human clinical trials. Local routes such as aerosol delivery to the lung are particularly well suited to use with liposomes containing immunomodulators. Polypeptides can also enhance the interaction of an immunomodulator with the immune system via increased immunostimulation; this can provide a means to enhance oral delivery and to achieve depot effects. Polysaccharide microspheres have been shown to be effective biodegradable carriers of immunomodulators. Finally, genetically engineered bacteria, viruses and mammalian cells may function as delivery systems for immunomodulatory peptides and proteins. Attenuated Salmonella strains can deliver immunomodulators to the gut-associated lymphoid tissue, liver and spleen. In mouse experiments using tumour cells producing granulocyte-macrophage colony-stimulating factor (GM-CSF), irradiated tumour preparations produced GM-CSF and were capable of eliciting effective cell-mediated immune responses, including destruction and elimination of tumour as well as resistance to tumour challenge (i.e. memory response). A wide variety of immunomodulators have been tested using this strategy; IL-2 and GM-CSF are among the most potent inducers of both cell-mediated effector and memory responses. In summary, use of delivery systems can significantly enhance the immunomodulatory potential of polypeptides and proteins.

Lipoteichoic acid preparations of gram-positive bacteria induce interleukin-12 through a CD14-dependent pathway

Interleukin 12 (IL-12) strongly augments gamma interferon production by natural killer (NK) and T cells. IL-12 also promotes effective cell-mediated immune responses, which are particularly important against intracellular bacteria such as Listeria monocytogenes. While the lipopolysaccharide (LPS) of gram-negative bacteria induces monocyte production of IL-12, the relevant gram-positive components which induce IL-12 production are uncharacterized. We used the human monocytic cell line THP-1 to study IL-12 induction by gram-positive bacteria. Muramyl dipeptides as well as the major muramyl tetrapeptide component of Streptococcus pneumoniae were inactive for inducing IL-12. In contrast, lipoteichoic acid (LTA), a predominant surface glycolipid of gram-positive bacteria, potently induced IL-12 p40 gene expression. A competitive LPS antagonist, Rhodobacter sphaeroides LPS, inhibited LTA-induced IL-12 production, suggesting a common pathway for LPS and LTA in IL-12 activation. Pretreatment of cells with anti-CD14 monoclonal antibody blocked both LPS and LTA induction of IL-12 p40 expression. LTA also induced Thl development in naive CD4 T cells by an IL-12-dependent mechanism, indicating direct induction of physiologic levels of IL-12. Together, these results show that LTA is a potent surface structure of gram-positive bacteria which induces IL-12 in monocytes through a CD14-mediated pathway.

Gene therapy and viral vaccination: the interface

Live viral vaccines have had a major impact on the incidence of acute virus infections world-wide. Virus infections recognised as future vaccine targets will require a modified approach based on a detailed understanding of the immunobiology of specific infections combined with the application of new technologies designed to generate specific and appropriate protective immunity. A similar vector technology directed at in vivo gene delivery is currently being exploited both for gene therapy and vaccination. The induction of an immune response to an expressed transgene represents a potential hazard for a gene therapy protocol but is the object of a vaccine strategy. In vivo gene delivery using replication-competent or replication-deficient viral vector systems and by direct transfer of naked DNA can generate an effective humoral, secretory and cell-mediated immune response to expressed transgenes.

Regulation of the immune response to Candida albicans monocytes and progesterone

Recurrent vaginal infections caused by Candida albicans are associated with decreased cell-mediated immune responses. We report that circulating progesterone levels and variations between persons in the activity of their monocytes are two of the factors that influence the extent of lymphocyte proliferation in response to C. albicans. With the use of peripheral blood mononuclear cells from five men and four women, removal of the monocytes increased the lymphocyte response to C. albicans antigens in eight persons. The percentage increase in proliferation was inversely proportional to the proliferative response observed when the monocytes were present, suggesting that differences existed between persons in the ability of their monocytes to down regulate the response. An approximate 50% decrease in C. albicans-induced lymphocyte proliferation was observed in the presence of luteal-phase levels (25 ng/ml), as opposed to proliferative-phase levels (0.15 ng/ml) of progesterone. Monocyte removal obviated the ability of 25 ng/ml progesterone to inhibit this response, suggesting that progesterone inhibited lymphocyte proliferation through a monocyte-dependent mechanism. Thus fluctuations in a woman's monocyte activity in response to genetic, hormonal, or environmental factors may influence her ability to mount an effective cell-mediated immune response to C. albicans.

Prolonged Cutaneous Herpes Zoster in Acquired Immunodeficiency Syndrome

We described the development of prolonged disseminated cutaneous herpes zoster in two patients with acquired immunodeficiency syndrome. Both patients developed hyperkeratotic, verrucous lesions that progressed despite acyclovir therapy. The biopsy specimens were typical of herpes infection. The development of acyclovir-resistant varicella-zoster virus during therapy was suspected clinically in the first patient and documented in vitro in the second patient. The inability to mount an effective cell-mediated immune response contributed to the prolonged course of cutaneous zoster in our patients. The hyperkeratotic nature of the skin lesions may reflect their chronic nature. Treatment with inadequate doses of acyclovir, allowing viral persistence and the selection of resistant strains of virus, may also be implicated. We recommend prolonged high-dose intravenous acyclovir therapy in the initial management of herpes zoster in patients with acquired immunodeficiency syndrome.

Spontaneous proliferation of peripheral mononuclear cells in natural measles virus infection: Identification of dividing cells and correlation with mitogen responsiveness

Spontaneous proliferation of peripheral mononuclear cells is pronounced following measles virus infection at a time when patients mount effective humoral and cell-mediated immune responses and manifest a range of poorly understood immunologic abnormalities. We found spontaneous activity (measles 8000 ± 1200 cpm vs control 1900 ± 350 cpm; P < 0.05) to wax and wane abruptly during the first week after the rash in parallel with expression of the lymphocyte activation marker OKT10. At peak activity, approximately 10% of circulating mononuclear cells were actively synthesizing DNA. Double labeling of individual mononuclear cells with autoradiography and immunoperoxidase demonstrated that B and T lymphocytes as well as monocytes participate in the spontaneous activity. Proliferative activity was increased 3- to 20-fold over control levels in all PBMC subsets such that close to one-third of circulating B cells and monocytes and 5–10% of CD4- and CD8-positive T cells were preparing to divide. Mitogen responsiveness was generally decreased in measles patients (58,800 ± 4600 cpm vs control 97,700 ± 15,500 cpm; P < 0.002). Neither spontaneous proliferation nor mitogen responsiveness was correlated with age, sex, or the presence of complications. Patients with the lowest mitogen responses, however, had the greatest increases in B cell ( P < 0.03) and CD8-positive T cell ( P < 0.05) proliferation. These data demonstrate that all major immunologic cell types proliferate in response to measles virus infection. Mechanisms by which spontaneous proliferative activity in individual mononuclear subsets could contribute to depressed mitogen responsiveness are discussed.

Antigen presentation in patients with recrudescent orofacial herpes simplex virus infections

Recovery from epidermal herpes simplex virus (HSV) infection depends primarily on development of an effective cell-mediated immune response, possibly generated following antigen (Ag) presentation by epidermal cells (EC). The ability of EC to present HSV Ag was investigated in 12 subjects with occasional recrudescent facial HSV infections. All had circulating HSV specific antibodies and cell-mediated immunity to the virus. Peripheral blood mononuclear cell suspensions, depleted of antigen presenting cells (APC) by glass adherence and then enriched for T cells by adsorption on nylon wool columns, did not proliferate in response to HSV Ag. Both EC suspensions, prepared from suction blister roofs, and glass-adherent peripheral blood mononuclear cells (AC) preincubated with ultraviolet-inactivated HSV, reconstituted the T-cell proliferative response to HSV. EC were more efficient than AC at presenting HSV Ag to T cells. Depletion of CD1+ cells from EC suspensions by cell sorting reduced their ability to present HSV Ag and augmentation of CD1+ cell numbers supplemented it. Preincubation of EC or AC with monoclonal antibodies to major histocompatibility complex class II antigens DP, DQ or DR, blocked the lymphoproliferative response to HSV Ag. Evidence was obtained that cells co-ordinately expressing products of the DP, DQ and DR loci are involved in presentation of HSV Ag by both EC and AC.

The reconstitution of cell-mediated immunity in the cutaneous lesions of lepromatous leprosy by recombinant interleukin 2.

Human rIL-2 (10-30 micrograms) was injected intradermally into the skin of patients with lepromatous leprosy with high bacillary loads. All patients responded to the lymphokine with local areas of induration that peaked at 24 h and persisted for 4-7 d irrespective of whether the site was "normal skin" or a nodular lesion. Within 24 h there was an extensive emigration of T cells and monocytes into the site. The percentage of the dermis infiltrated by mononuclear cells increased by more than sevenfold, peaking at 4 d and persisting for greater than 15 d. Both CD4+ and CD8+ T cells entered the site. T cells of CD4+ phenotype predominated at 2-7 d but by 11 d, CD8+ cells were predominant. Considerable numbers of T6+ Langerhans' cells appeared in the dermis by 72 h and persisted for 3 wk. By 4 d the thickness of the overlying epidermis had increased twofold, and keratinocytes were expressing MHC class II antigen and the IFN-gamma-induced peptide IP-10. Starting at 48 h, there was an extensive destruction of mononuclear phagocytes that contained structurally intact or fragmented M. leprae observed at the electron microscope level. The organisms, either free or contained within endocytic vacuoles, were discharged into the extracellular space and then reingested by blood-borne monocytes. This was followed by marked reductions in the number of acid-fast organisms in the injected site, evident as early as 4-7 d and more marked at 2-3 wk after injection. 13 of 15 patients exhibited a disposal of acid-fast bacilli ranging from 5- to 1,000-fold with a mean value of approximately 100-fold. The administration of IL-2 leads to the generation of an effective cell-mediated immune response, recapitulating an antigen-driven event and leading to striking local reductions in M. leprae. In comparison with the purified protein derivative of tuberculin reaction, bacilli are cleared more promptly, although emigratory cells persist for a shorter time.