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Biomedical subjects

L A Pirofski

Publications and source records attributed to L A Pirofski.

At least 19 recordsLinked to original sources
PubMed2001

Adjunctive immune therapy for fungal infections.

Fungal infections in immunocompromised patients can pose difficult problems in clinical management, because the available antifungal chemotherapy is often unable to eradicate the infection in these people. Hence, the use of immune modulating therapy to augment impaired host immune responses--and thus enhance the efficacy of antifungal drugs--is a reasonable approach to improve the prognosis of fungal infections. Advances in biotechnology have produced a variety of biological response modifiers with the potential to serve as adjunctive immune therapy for the treatment of fungal infections, including cytokines, monoclonal antibodies, and cell growth factors. In recent years, immune-modulating therapies have been studied in an effort to define their potential use for the treatment of fungal infections. Much of the available information on the use of this approach is encouraging and invites further investigation--with the caveats that the information is mostly anecdotal and that immune-modulating therapy occasionally has produced adverse effects.

Adjuvants, Immunologic↗
PubMed2001

Polysaccharides, mimotopes and vaccines for fungal and encapsulated pathogens.

Vaccination is a rational alternative to treatment for Cryptococcus neoformans infections, as these infections are currently intractable in immunocompromised (including HIV-infected) individuals. Vaccines composed of the cryptococcal capsular polysaccharide glucuronoxylomannan (GXM), the key C. neoformans virulence factor, elicit protective antibodies in mice, although deleterious antibodies can also be induced. By contrast, polysaccharides are poor immunogens in HIV-infected humans and others with B-cell defects. Peptide mimotopes of GXM can induce protective immunity to C. neoformans in mice, however, our knowledge of the mechanisms of mimotope-induced protection is incomplete and further work is needed if polysaccharide- or mimotope-based vaccines are to be used to manage C. neoformans infection.

Antibodies, Fungal↗
PubMed2001

Vaccination against infectious disease following hematopoietic stem cell transplantation.

Patients undergoing hematopoietic stem cell transplantation (HSCT) experience a prolonged period of dysfunctional immunity associated with an increased risk of bacterial and viral infections. Effective approaches toward vaccinating patients against common pathogens are being explored but are limited by poor levels of responsiveness. Relevant studies examining the nature of reconstitution of cellular and humoral immunity and its impact on vaccination strategies against infectious pathogens are reviewed. Following transplantation, deficiencies in cellular immunity are characterized by the inversion of CD4/CD8 ratios, a decreased proliferative response to mitogens, and the development of anergy to recall antigens as measured by delayed-type hypersensitivity testing. The impact on humoral immunity consists of decreased levels of circulating immunoglobulin, impaired immunoglobulin class switching, and a loss of complexity in immunoglobulin gene rearrangement patterns. In this setting, a loss of protective immunity has been demonstrated against viral and bacterial pathogens previously targeted by childhood vaccination. Infections due to encapsulated bacterial organisms such as Streptococcus pneumoniae and Haemophilus influenzae type B remain prevalent even in the late posttransplantation period. The efficacy of vaccination following HSCT is influenced by the time elapsed since transplantation, the nature of the hematopoietic graft, the use of serial immunization, and the presence of graft-versus-host disease. Strategies to enhance vaccine efficacy include pretransplantation immunization of the stem cell donor and the use of cytokine adjuvants.

B-Lymphocytes↗
PubMed1998

Characterization of a murine monoclonal antibody to Cryptococcus neoformans polysaccharide that is a candidate for human therapeutic studies.

The murine monoclonal antibody (MAb) 18B7 [immunoglobulin G1(kappa)] is in preclinical development for treatment of Cryptococcus neoformans infections. In anticipation of its use in humans, we defined the serological and biological properties of MAb 18B7 in detail. Structural comparison to the related protective MAb 2H1 revealed conservation of the antigen binding site despite several amino acid differences. MAb 18B7 was shown by immunofluorescence and agglutination studies to bind to all four serotypes of C. neoformans, opsonize C. neoformans serotypes A and D, enhance human and mouse effector cell antifungal activity, and activate the complement pathway leading to deposition of complement component 3 (C3) on the cryptococcal capsule. Administration of MAb 18B7 to mice led to rapid clearance of serum cryptococcal antigen and deposition in the liver and spleen. Immunohistochemical studies revealed that MAb 18B7 bound to capsular glucuronoxylomannan in infected mouse tissues. No reactivity of MAb 18B7 with normal human, rat, or mouse tissues was detected. The results show that both the variable and constant regions of MAb 18B7 are biologically functional and support the use of this MAb in human therapeutic trials.

Amino Acid Sequence↗
PubMed1998

Antifungal activity of a human antiglucuronoxylomannan antibody.

The human immunoglobulin M (IgM) monoclonal antibody (MAb) 2E9 binds the glucuronoxylomannan (GXM) of Cryptococcus neoformans serotypes A, B, and D. This study was undertaken to determine the opsonic efficacy of 2E9 and its ability to promote the antifungal activity of human polymorphonuclear neutrophils (PMNs) against C. neoformans. We incubated purified PMNs with fluorescein isothiocyanate-labeled C. neoformans cells that were treated with the GXM IgM 2E9, IgM antibodies that do not bind GXM, and rabbit and human factor-B-deficient serum as complement sources. PMN-associated C. neoformans cells fluoresced and were detected with a fluorescence-activated cell sorter. The amount of phagocytosis was defined as the percent fluorescing PMNs, which was 37% for yeast cells opsonized with 2E9 plus rabbit serum and 57% for yeast cells opsonized with 2E9 plus factor-B-deficient serum. Phagocytosis was significantly greater for yeast cells that were treated with 2E9 plus a complement source than for yeast cells treated with the complement sources alone or treated with the control IgMs alone or with the complement sources. Fluorescence quenching and light and electron microscopy of the phagocytosis mixtures revealed that 2E9-opsonized yeast cells were internalized by PMNs. Maximal inhibition of C. neoformans growth occurred when PMNs were cocultured with yeast cells that were opsonized with 2E9 plus a complement source. Our data demonstrate that the human GXM IgM 2E9 can mediate PMN phagocytosis and C. neoformans growth inhibition in vitro. These findings strongly suggest that antibody-mediated deposition of complement components on the cryptococcal capsule can augment PMN complement receptor-mediated antifungal activity. Antibody activation of complement-mediated effector cell antifungal mechanisms may play a role in host defense against cryptococcosis and represents a goal for the use of MAbs to treat or prevent human C. neoformans infections.

Antibodies, Fungal↗
PubMed1998

Use of licensed vaccines for active immunization of the immunocompromised host.

The latter part of the 20th century has witnessed an unprecedented rise in the number of individuals with impaired immunity. This is primarily attributable to the increased development and use of antineoplastic therapy for malignancies, organ and bone marrow transplantation, and the AIDS epidemic. Individuals with impaired immunity are often at increased risk for infections, and they can experience more severe and complicated courses of infection. The lack of therapy for a variety of viruses and the rise in antimicrobial resistance of many pathogens have focused attention on vaccination to prevent infectious diseases. The efficacy of most licensed vaccines has been established in immunocompetent hosts. However, there is also considerable experience with most vaccines in those with impaired immunity. We reviewed the use of licensed live, inactivated, and polysaccharide vaccines in this group, and several themes emerged: (i) most vaccines are less immunogenic in those with impaired immunity than in normal individuals; (ii) live vaccines are generally contraindicated in this group; and (iii) the efficacy of many commonly used vaccines has not been established in people with impaired immunity. This review suggests that for most vaccines there are little or no efficacy data in those with impaired immunity but their use in this patient group is generally safe.

Drug Approval↗
PubMed1997

Peptide epitopes recognized by a human anti-cryptococcal glucuronoxylomannan antibody.

Cryptococcus neoformans causes meningitis in 6 to 8% of individuals with AIDS. Recently, immunotherapeutic modalities including antibody therapy have been proposed for the treatment of cryptococcal meningitis in AIDS patients. This is a rational approach because existing antifungal agents fail to eradicate the infection in the setting of profound immunosuppression. Both murine and human antibodies elicited by the investigational cryptococcal capsular polysaccharide vaccine glucuronoxylomannan-tetanus toxoid (GXM-TT) have been shown to be biologically functional in different model systems. The human immunoglobulin M (lambda) GXM monoclonal antibody (MAb) 2E9 expresses idiotypes that are also found in naturally occurring anti-GXM antibodies and opsonic GXM-TT sera. However, the specificity of human anti-GXM antibodies and their possible role in protection against cryptococcosis are not known. In an effort to discover epitopes that are recognized by human anti-GXM antibodies, we screened a random decapeptide phage display library with the human anti-GXM MAb 2E9. An enzyme-linked immunosorbent assay (ELISA)-based screening method led to the selection of phages with peptide inserts that bound 2E9 and inhibited 2E9-GXM binding. Analysis of the amino acid sequences of these phages revealed an increased frequency of combinations of QTGLD residues. Inhibition ELISAs demonstrated that phages with QTG/TL/D motifs inhibited 2E9-GXM binding better than phages with different motifs. A peptide synthesized from one of the inhibitory phages, peptide 13 (GMDGT QLDRW), inhibited GXM binding to solid-phase 2E9 and 2E9 binding to solid-phase GXM. Peptide 13 also inhibited the GXM binding of GXM-TT immune sera and naturally occurring serum antibodies from human immunodeficiency virus (HIV)-negative, but not HIV-positive, individuals. Taken together, our data indicate that the peptide epitopes selected by 2E9 mimic GXM epitopes and that peptide 13 may be a mimotope of a GXM epitope that is recognized by human anti-GXM antibodies.

AIDS-Related Opportunistic Infections↗
PubMed1997

Extracellular proteins of Cryptococcus neoformans and host antibody response.

Proteins secreted by the fungal pathogen Cryptococcus neoformans may be involved in invasion and could be useful in vaccine design. Despite the medical importance of this fungus, little is known about its extracellular proteins or the immune response to these antigens. To study C. neoformans extracellular proteins, 12 strains were metabolically radiolabeled and protein supernatants were analyzed. Both strain- and growth condition-dependent differences were observed. Enzymatic assays of filtered culture supernatants revealed butyrate esterase and caprylate esterase lipase activity for 11 of 12 strains, as well as acid phosphatase, naphthol-AS-BI-phosphohydrolase, and beta-glucosidase activities in some strains. Serum from infected rodents immunoprecipitated several secreted proteins, consistent with in vivo expression and development of an antibody response. For strain 24067, two immunodominant species, of approximately 75 and 30 kDa, were recognized. The relative intensity of the autoradiographic bands depended on the route of infection for both rats and mice. In summary, our results indicate that (i) there are multiple proteins in C. neoformans culture supernatants, (ii) there are strain differences in supernatant protein profiles, (iii) there are differences in supernatant protein profile depending on the growth conditions, (iv) there are several new extracellular and/or cell-associated enzymatic activities, and (v) antibodies to several supernatant proteins are made in the course of infection.

Acid Phosphatase↗
PubMed1997

Fc gammaRIIa polymorphism in human immunodeficiency virus-infected children with invasive pneumococcal disease.

Invasive pneumococcal disease (IPD) occurs frequently in HIV-infected children and adults. Defects in complement function, opsonic capsular antibodies, and Fc receptor antibody-mediated phagocytosis could contribute to impaired host defense against Streptococcus pneumoniae. The objective of this study was to define the distribution of the three Fc gammaRIIa genotypes in HIV+ children, including those with IPD. Forty-eight HIV+ Hispanic children, including eight with IPD, followed at Bronx-Lebanon Hospital Center, Bronx, New York, nine HIV+ adults with IPD, and 56 HIV- Hispanic control subjects were studied. The children and adults were identified retrospectively except for one child who developed IPD during the study. Fc gammaRIIa genotypes were determined by PCR amplification of the Fc gammaRIIa locus from genomic DNA samples and hybridization of the PCR products with allele-specific oligonucleotides. Naturally occurring serum antibodies reactive with four pneumococcal polysaccharide serotypes were determined by ELISA in seven of eight children with IPD. There were no statistical differences in Fc gammaRIIa genotypes between HIV+ children with and without IPD, HIV+ adults with IPD, or HIV- Hispanics. The predominant IgG subclass of pneumococcal polysaccharide binding antibodies in the seven HIV+ children with IPD studied was IgG1. The distribution of Fc gammaRIIa genotypes in HIV+ children with and without IPD is similar to that of the normal Hispanic population. The prospect of passive immunotherapy with specific anticapsular antibodies might be a promising alternative for the treatment and/or prevention of IPD in HIV+ children and other immunodeficient groups.

AIDS-Related Opportunistic Infections↗
PubMed1996

Cryptococcus neoformans: paradigm for the role of antibody immunity against fungi?

Cryptococcus neoformans is an encapsulated fungus that is a frequent cause of life-threatening infections in patients with AIDS. C. neoformans has many similarities with encapsulated bacteria such as S. pneumoniae and H. influenzae for which antibody immunity is important in protection. However the role of antibody immunity in protection against C. neoformans has been controversial. Experiments with polyclonal sera have produced conflicting evidence for and against the importance of antibody immunity in host defense. Experiments with monoclonal antibodies (mAb) to the C. neoformans capsular polysaccharide (CPS) have revealed the existence of protective, non-protective and disease-enhancing mAbs, suggesting that the divergent results obtained with polyclonal preparations may be a result of relative proportion of protective and non-protective antibodies in immune sera. Administration of protective mAbs can prolong survival, decrease organ fungal burden, and reduce serum polysaccharide antigen. In vitro experiments suggests that protective mAbs modify the course of infection by enhancing effector cell function against C. neoformans. Addition of mAb to antifungal drugs enhances their efficacy against C. neoformans in vivo and in vitro. Human-mouse chimeric antibodies with activity against C. neoformans have been constructed. A highly immunogenic capsular polysaccharide-protein vaccine has been synthesized that elicits protective antibodies in mice. Antibody immunity elicited by conjugate vaccines or provided by passive administration may be useful in the prevention treatment of human cryptococcal infections.

Animals↗
PubMed1996

Opsonization of Cryptococcus neoformans by human anticryptococcal glucuronoxylomannan antibodies.

Cryptococcal meningitis occurs in 6 to 8% of human immunodeficiency virus-infected individuals. Despite the availability of powerful antifungal agents that are active against Cryptococcus neoformans, these drugs generally fail to cure cryptococcal infections in immunocompromised hosts. Alternative approaches to prevention and therapy of cryptococcosis are urgently needed. Complement promotes phagocytosis of C. neoformans, but human antibodies to cryptococcal capsular polysaccharide have not been shown to function as complement-independent opsonins. The goal of our studies was to characterize the in vitro biological function of human antibodies to glucuronoxylomannan (GXM) from individuals immunized with a GXM-tetanus toxoid (GXM-TT) vaccine. We studied sera from nine vaccinees that manifested good serologic responses to GXM-TT. The results indicate that GXM-TT-elicited antibodies promote phagocytosis of C. neoformans by both murine J774 cells and human peripheral blood mononuclear cells (PBMCs). The two sera with the highest titers of anti-GXM immunoglobulin G2 antibodies were the most opsonic. When PBMC Fc gamma RIIa receptors were blocked, a 75% decrease in phagocytosis occurred following incubation of the PBMCs with C. neoformans opsonized with these sera. Our data indicate that, in the absence of complement, human anti-GXM-TT antibodies are opsonic and that antibodies of the immunoglobulin G2 isotype are effective opsonins.

Adjuvants, Immunologic↗
PubMed1995

Antibodies to the Cryptococcus neoformans capsular glucuronoxylomannan are ubiquitous in serum from HIV+ and HIV- individuals.

Murine MoAbs to the Cryptococcus neoformans capsular glucuronoxylomannan (GXM) polysaccharide are protective in mice in vivo and in vitro. The prevalence of protective anti-GXM antibodies in human serum is unknown. To provide further insight into the human antibody response to C. neoformans we determined the prevalence, isotype, and IgG subclass utilization of human anti-GXM antibodies in HIV+ and HIV- sera by a sensitive antigen capture FLISA assay. One hundred and twenty-three sera from the Bronx Municipal Hospital Centre serum bank were studied retrospectively. Seventy were from HIV+ individuals, 10 with a history of cryptococcal meningitis (CM), and 53 were from HIV- individuals. Serum GXM determinations were also performed on 61 HIV+ sera. Our results demonstrated that anti-GXM IgG, IgA, and IgM are ubiquitous in both HIV+ (including those with CM), and HIV- sera. Anti-GXM IgA titres and total serum IgA concentration were elevated in HIV+ sera. Anti-GXM IgG antibodies were almost exclusively isotype-restricted to the IgG2 subclass. Our data also demonstrated elevations of anti-bovine serum albumin (BSA) titres in HIV+ sera. Taken together, our findings confirm hypergammaglobulinaemia and expansion of anti-protein (BSA) antibodies in HIV+ individuals and isotype restriction of human anti-carbohydrate (GXM) antibodies to the IgG2 subclass. Our report of ubiquitous anti-GXM antibodies of the IgG and IgA isotypes suggests that anti-GXM antibodies exist before HIV infection.

Antibodies, Fungal↗
PubMed1995

Mouse adenovirus type 1 causes a fatal hemorrhagic encephalomyelitis in adult C57BL/6 but not BALB/c mice.

Mouse adenovirus type 1 (MAV-1) produces a lethal disease in newborn or suckling mice characterized by infectious virus and viral lesions in multiple organs. Previous reports of MAV-1 infection of adult mice generally described serologic evidence of infection without morbidity or mortality. However, our current results demonstrate that MAV-1 causes a fatal illness in adult C57BL/6(B6) mice (50% lethal dose, [LD50], 10(3.0) PFU) but not in adult BALB/c mice at all of the doses tested (LD50, > or = 10(5.0) PFU). Adult (BALB/c x B6)F1 mice were intermediately susceptible (LD50, 10(4.5) PFU). Clinically, the sensitive B6 mice showed symptoms of acute central nervous system (CNS) disease, including tremors, seizures, ataxia, and paralysis. Light microscopic examination of CNS tissue from the B6 animals revealed petechial hemorrhages, edema, neovascularization, and mild inflammation in the brain and spinal cord. Analysis by electron microscopy showed evidence of inflammation, such as activated microglia, as well as swollen astrocytic endfeet and perivascular lipid deposition indicative of blood-brain barrier dysfunction. Outside of the CNS, the only significant pathological findings were foci of cytolysis in the splenic white pulp. Assessment of viral replication from multiple tissues was performed by using RNase protection assays with an antisense MAV-1 early region 1a probe. The greatest amounts of viral mRNA in MAV-1-infected B6 animals were located in the brain and spinal cord. Less viral message was detected in the spleen, lungs, and heart. No viral mRNA was detected in BALB/c mouse tissue, with the exception of low levels in the heart. Viral titers of organ tissues were also determined and were concordant with RNase protection findings on the brain and spinal cord but failed to demonstrate significant infectious virus in additional organs. Our experiments demonstrate that MAV-1 has a striking tropism for the CNS that is strain dependent, and this provides an informative in vivo model for the study of adenoviral pathogenesis.

Adenoviridae↗
PubMed1994

Molecular and idiotypic analysis of antibodies to Cryptococcus neoformans glucuronoxylomannan.

Antibodies to the Cryptococcus neoformans capsular glucuronoxylomannan (GXM) form the basis of two potential therapeutic intervention strategies, i.e., conjugate vaccines and passive antibody therapy. To better understand the molecular basis of the antibody response, the heavy- and light-chain immunoglobulin variable region (VH and VL, respectively) sequences of seven monoclonal antibodies (MAbs) to GXM were determined. Rabbit anti-idiotypic serum was made to the previously characterized murine MAb 2H1 and used to study MAb 2H1 idiotype expression in other GXM-binding MAbs and immune sera. MAb E1 originated from a C3H/HeJ mouse immunized with C. neoformans serotype A polysaccharide. MAbs 471, 1255, 339, 3C2, 386, and 302 originated from BALB/c mice immunized with polysaccharide of serotypes A, A, B, C, D, and D, respectively, conjugated to sheep erythrocytes. In the E1, VH uses V11 from the T15 gene family and JH3 and has a D segment of three amino acids, and the VL uses a VKSer-like gene family element and JK5. In MAbs 471 and 3C2, the VH uses VH7183-like gene family elements and JH2 and has D segments of seven amino acids, and the VL uses VK5.1 and JK1. In MAbs 1255 and 339, the VH uses VH10-like gene elements and JH4 and has six codon D segments, and the VL uses a VK21-like gene element and JK5. In MAbs 302 and 386, respectively, the VH uses VHGAM-like gene elements and JH2 and JH3 and has six and four codon D segments, and VL uses VK4/5-like gene elements and JK1.VH usage, MAb 2H1 idiotype expression, and fine specificity mapping define a minimum of three GXM epitopes which elicit protective antibodies. The results confirm that the antibody response is highly restricted, suggest a close relationship between molecular structure and serological properties, and provide insight into protein structural motifs important for GXM binding.

Animals↗
PubMed1993

Antibody-mediated protection in mice with lethal intracerebral Cryptococcus neoformans infection.

The fungus Cryptococcus neoformans is an important opportunistic pathogen for patients with AIDS. C. neoformans infections frequently involve the brain and are often fatal. In the setting of AIDS C. neoformans infections are incurable and new treatment strategies are urgently needed. Passive administration of antibody is a potential therapeutic option for the prevention and treatment of C. neoformans. The IgG1 murine monoclonal antibody 2H1 to the capsular polysaccharide of C. neoformans was studied for its ability to modify the course of lethal intracerebral cryptococcal infection in mice. Intraperitoneal administration of antibody 2H1 resulted in small, yet significant, prolongations in the average survival of mice given intracerebral infection and reduced the number of C. neoformans colonies in brain tissue. Histopathological examination of brain tissues revealed a diffuse cryptococcal meningitis with fewer organisms in the brains of mice that received antibody 2H1 than in the control group. Thus, systemic administration of a monoclonal antibody can modify the course of lethal intracerebral C. neoformans infection in mice by prolonging survival and decreasing fungal burden in brain tissues.

Animals↗
PubMed1993

Variable region gene utilization and mutation in a group of neutralizing murine anti-human immunodeficiency virus type 1 principal neutralizing determinant antibodies.

The heavy (VH) and light (VL) chain variable region nucleotide sequences of four neutralizing anti-human immunodeficiency virus type 1 (HIV-1) murine monoclonal antibodies (mAbs) were determined. These mAbs bind to native gp120, recombinant gp120, and a linear HIV-1 principal neutralizing determinant (PND) peptide that spans amino acid 308-328. Three mAbs that bind to the same linear determinant, 110.3, 110.4, and 110.5, all use the same VL gene elements, a VK21 gene and JK2. These three mAbs also share the same VKJK junctional diversity and specific somatic mutations. They have identical VL immunoglobulin gene rearrangement patterns on Southern blot. Two of the antibodies, 110.4 and 110.5, also use the same VH gene elements, SB32-D-JH4, and have identical VD and DJ junctions and N sequences. Two different anti-HIV-1 PND murine mAbs reported by others, BAT123 and 0.5 beta, also use VK21-JK2, and BAT123 also uses the SB32 VH gene element. Although 110.3 uses the same VL region gene as 110.3 and 110.4, it uses a different VH gene that appears to be a member of the 7183 VH family. 110.6, an mAb that recognizes a discrete, overlapping PND compared to 110.3, 110.4, and 110.5, uses entirely different VH and VL gene elements and has unique immunoglobulin VH and VL rearrangement patterns. Our data, taken together with reports of the BAT123 and 0.5 beta mAb sequences, suggest that the murine antibody response to HIV-1 PND may be restricted to a small subset of VH and VL gene elements.

Amino Acid Sequence↗