Antibody responses of chimpanzees immunized with synthetic peptides corresponding to full-length V3 hypervariable loops of HIV-1 envelope glycoproteins

Immunization of primates or humans with human immunodeficiency virus type 1 (HIV-1) glycoproteins usually elicited moderate immune responses to the principal neutralizing determinant (PND) located within the V3 hypervariable loop of gp120. Since an antibody response to the PND appears to be protective, experiments were carried out to determine the responsiveness of chimpanzees to immunization with synthetic peptides corresponding to the full-length V3 loop. Seven chimpanzees (4 preimmunized with gp160, 2 preimmunized with HIV-1 antigens unrelated to gp160, and 1 unimmunized) were vaccinated with a mixture of full-length V3 loop peptides from 21 distinct HIV-1 isolates (clones) either in unconjugated form or linked to carrier proteins from HIV-1 nef and gag P18, respectively. Six chimpanzees developed high levels of antibodies to the peptides (dilution endpoints 1: greater than 25,000), and 5 had high levels of antibodies to gp120 from HIV-1IIIB (endpoint titers 1: greater than 500,000). Chimpanzees immunized with peptide-carrier conjugates (4) had antibodies to the carrier proteins nef and gag P18, respectively (endpoint titers 1: greater than or equal to 35,000). Virus-neutralizing (VN) antibodies were detected in sera of 5 of 7 chimpanzees, but were present at titers of 1: greater than or equal to 400 only in sera of 2 chimpanzees. One of these was challenged with HIV-1 and was protected against infection, as reported elsewhere. The antibodies were primarily specific for the HIV-1 isolate used for primary immunization before boosting with peptides. The relatively low dilution endpoints of VN antibodies as compared with endpoints determined by site-specific immunoassays probably can be ascribed to imperfect mimicry of conformational epitopes by synthetic peptides. Nevertheless, sequential or simultaneous immunization with recombinant envelope glycoproteins of HIV-1 and selected synthetic peptides offers an approach for eliciting protective immunity against HIV-1.

Hemin stimulation of hemopoiesis in murine long-term bone marrow culture

The effect of various concentrations of exogenous hemin on cellularity and hemopoietic clonal potential of cells maintained in murine long-term marrow cultures (LTBMC) was studied. Hemin, at concentrations of 1 and 10 microM, was added weekly to LTBMC and was found to produce a significant increase in cellularity for up to 8 weeks in culture. Lower concentrations of hemin (0.1 microM) were more effective for sustained cellularity in older cultures (10-12 weeks). Prior exposure of the adherent cell layer to high concentrations of hemin (10 microM) was found to have a beneficial effect on the support of newly seeded cultures; however, the effect of lower hemin concentrations (0.1-1 microM) on stromal cell layer formation was not significant. Supplementation of hemin for the first week in culture increased cumulative cell production as well as the number of granulocyte-macrophage colony-forming units (CFU-GM), and longevity of hemopoiesis in LTBMC was significantly increased with 0.1 microM hemin. In contrast with data obtained in short-term cultures, hemin in this system primarily affected the myeloid line of differentiation, whereas there was a less noticeable effect on the early erythroid progenitors (erythroid burst-forming units, BFU-E). Hemin, at 0.1 microM, increased spleen colony-forming units (CFU-S) to numbers several-fold higher than those of the control. Results suggest that hemin may produce mobilization of hemopoietic cells and committed precursors from adherent cells into suspension. Further, supplementation with hemin in LTBMC significantly increased the myeloid progenitor compartment and longevity of culture without altering the erythroid compartment.

Confronting the hypervariability of an immunodominant epitope eliciting virus neutralizing antibodies from the envelope glycoprotein of the human immunodeficiency virus type 1 (HIV-1)--II. Synthetic peptides linked to HIV-1 carrier proteins gag and nef

Combining of subtype specific peptides from the hypervariable loop of the envelope glycoprotein gp120 of divergent HIV-1 isolates may help in designing a broadly protective immunogen against HIV-1 infection. To enhance the immunogenicity of such a polyvalent antigen, in the absence of oil-containing adjuvants, it is necessary to link the peptides to a protein carrier. It is preferable to use as carriers those proteins from HIV-1 itself which may contribute to eliciting protective immunity. The structural and non-structural proteins, gag P18 and nef, respectively, which can be prepared in high yields by recombinant DNA techniques in Escherichia coli, were selected for this purpose. The corresponding peptide-protein conjugates, each containing 21 distinct peptides, were prepared using the cross-linking reagents N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP) or m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (sulfo-MBS). Conjugates prepared by the second method elicited approximately 10-100 times higher levels of antibodies recognizing the homologous peptides and the HIV-1 envelope glycoproteins. The sulfo-MBS conjugation procedure preserved the antigenicity of both gag P18 and nef and the respective conjugates elicited an immune response to these proteins. Despite the low immunization dose of single peptides (10 micrograms) present in the mixture of peptides collectively linked to the carriers, antibody responses to most of the individual peptides were high (dilution endpoints 1: greater than 16,000, 1: greater than 80,000 for the nef and gag P18 conjugates, respectively). Conjugates consisting of a multitude of HIV-1 envelope-derived peptides in combination with gag P18 and nef carriers are expected to elicit broadly protective immunity against distinct HIV-1 subtypes.

Peptides mimicking selected disulfide loops in HIV-1 gp120, other than V3, do not elicit virus-neutralizing antibodies

The positions of all 9 intrachain disulfide bonds within the envelope glycoprotein gp120 of the human immunodeficiency virus (HIV-1) have been established recently. Peptides expected to mimic some of the disulfide-bonded domains [(120-133)-(203-221); (133-138)-(164-203); (224-254); (391-425) and (385-392)-(425-452)] were synthesized. All peptides, except (120-133)-(203-221), elicited in immunized rabbits relatively high levels of antibodies reacting with gp120 in enzyme-linked immunosorbent assay (ELISA) and/or Western immunoblot assays. However, these antibodies failed to neutralize the infectivity of HIV-1. Combined with earlier reports concerning other gp120 loop peptides, these results confirm the uniqueness of the V3 (303-338) loop in encompassing a principal determinant(s) involved in virus neutralization.

[Report of six cases of mental complications after cataractopiesis]

Six cases of mental complications after cataract extraction performed on 779 patients by the author when he worked at Do Ye Ha Hospital of Algeria were reported in this paper. The symptoms included confusion, agitation, schizophrenia, aberrant behavior and nervousness. The treatment consisted of sedative and psychotherapy. The patients were all recovered within 72 hours. The methods for preventing mental complications after operation are discussed.

Plasma membrane-associated proteins with the ability to partially inhibit perforin-mediated lysis

Cytolytic lymphocytes have previously been reported to be resistant to the lytic effects of perforin. In this work, plasma membrane proteins from a CTL cell line were fractionated by HPLC, and the eluted fractions were collected based on their ability to inhibit perforin-mediated hemolysis. Three proteins with inhibitory activity were thus purified, the serine esterase MCSP-3/granzyme F and the histones H2B and H3. A commercial source of H2B was able to potently inhibit perforin-mediated lysis, and it was confirmed by FACS analysis that H2B is in fact present on the surface of cytolytic cells. However, H2B was also found on the surface of perforin-susceptible tumor cell lines, indicating that the histones may partially inhibit perforin-mediated lysis in vitro, but that they do not represent the factor conferring specific resistance on cytolytic lymphocytes. The origin of the surface histones and the possible role of the surface MCSP-3/granzyme F are discussed.

Comparison of hemin enhancement of burst-forming units-erythroid clonal efficiency by progenitor cells from normal and HIV-infected patients

The ability of peripheral-blood hematopoietic progenitor cells from AIDS patients and normal controls to respond to erythropoietin (Epo) was assessed for burst-forming units-erythroid (BFU-E). BFU-E colony formation from AIDS patients' peripheral blood responded to a wide range of Epo concentrations (0.5-4 U) in a similar manner as erythroid progenitors obtained from normal peripheral blood. The optimum dose response of BFU-E to Epo was 2 U which resulted in generation of 71 +/- 4 BFU-E in AIDS patients (n = 10), as compared to 77 +/- 5 BFU-E in normal donors (n = 3). The optimum concentration range of hemin enhancement of erythroid progenitor BFU-E was 10-50 microM. In all instances, Epo was essential for BFU-E growth. Inclusion of hemin at a concentration of 10 microM in AIDS patients' peripheral-blood erythroid progenitor cells resulted in enhancement of BFU-E by 136-215%. Similarly, inclusion of hemin (10-100 microM) in normal bone marrow erythroid progenitor cell cultures resulted in enhancement of BFU-E. Inclusion of an equivalent amount of iron or tin protoporphyrin to progenitors cells from AIDS patients' peripheral blood had no effect on the number of colonies observed. On the other hand, inclusion of another heme analogue, zinc protoporphyrin, in AIDS or normal cultures resulted in a 50% suppression of BFU-E colony formation. These results demonstrate that peripheral-blood mononuclear cells from AIDS patients retain the capacity to generate erythroid precursors such as BFU-E in the presence of Epo, and that hemin has a specific enhancement effect on growth of BFU-E colony formation obtained from peripheral blood or bone marrow cells.

Development of technology for linking photosensitizers to a model monoclonal antibody

A procedure is described whereby the photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) was covalently linked to a model monoclonal antibody in a manner which is reproducible, quantifiable, and retains both the biological activity of the antibody and the cytotoxicity of the photosensitizer. Preliminary steps involved the linkage of BPD-MA to a modified polyvinyl alcohol (PVA) backbone, followed by conjugation to the antibody using heterobifunctional linking technology. Briefly, polyvinyl alcohol (MW ca. 10,000) was modified with 2-fluoro-1-methyl pyridinium toluene-4-sulfonate and 1,6-hexanediamine to produce side chains containing free amino groups. The free carboxyl group of BPD-MA was utilized to conjugate photosensitizer molecules to modified PVA using a standard carbodiimide reaction. Final linkage of the PVA-BPD to a model monoclonal antibody involved further substitution of the carrier with 3-mercaptopropionic acid and carbodiimide to introduce 3-4 sulfhydryl residues per carrier molecule, and introduction of sulfo-m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester residues to the monoclonal (3-4 residues/molecule). Conjugation was effected by reaction of the two species at pH 5.5 for 18 h. Detailed methodology and tests for efficacy of the procedure are provided.

[Evaluation of combined use of ultrasonography and beta-hCG determination in diagnosis of pelvic lesions of malignant trophoblastic disease]

The results of combined use of ultrasonography and beta-hCG determination for diagnosis of pelvic lesions of malignant trophoblastic disease in 73 cases were reported. Abnormal ultrasonograms and elevated beta-hCG levels were found in 53 of 55 cases of invasive mole and all 20 cases of choriocarcinoma. The location and extent of the pelvic lesions were clearly defined by ultrasonography. Moreover, there was a high correlation rate between ultrasonograms and beta-hCG levels. Surgico-pathological diagnosis was available in 17 cases. Based on these data, the authors emphasize that in improving the accuracy of diagnosis and locating the pelvic lesions ultrasonography in combination with beta-hCG determinations should be used as a routine procedure in suspected cases of pelvic lesion of malignant trophoblastic disease.

[Prenatal sex identification with biotinylated human Y-specific DNA probe]

Using biotinylated human Y-specific DNA probe PHY2.1 and Cos 84, we carried out Southern and dot hybridization with human DNA from artificially aborted chorionic villi, and with DNA of peripheral lymphocytes from normal male and female. The results show that PHY2.1 may be applied in prenatal sex identification both by Southern and by dot hybridization but with Cos 84, only Southern hybridization could be used.

Purification of a membrane-associated serine esterase from murine cytotoxic T lymphocytes by a single reverse-phase column

The plasma and organelle membranes of a cytotoxic T lymphocyte line, CTLL-R8, were isolated by subcellular fractionation. After dissolving in detergent-containing buffer, the membrane proteins were isolated by high-performance liquid chromatography on a single reverse-phase column. The serine esterase activity in the fractions was detected by measuring hydrolysis of the ester compound N alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester. A major band was revealed in the fraction with highest serine esterase activity. Under sodium dodecyl sulfate-polyacrylamide gel electrophoresis, this band assumes a molecular weight of about 30 kDa. The amino-terminal sequence of the protein was analyzed and shows 100% identity with that of MCSP-3/granzyme F, a soluble serine esterase previously identified in the cytoplasmic granules of cytotoxic T lymphocytes. Modifications of this reverse-phase column method would thus represent a simple, convenient strategy for obtaining high yields of all the lymphocyte surface proteases, which could then be further characterized for function.

[Uses of improved Gersuny-Lowsley's operation in radical surgery for vulvar cancer]

As a tumor of the body surface, theoretically there should be no problem to achieve an early diagnosis and early treatment in carcinoma of the vulva. However, factually it is not always the case. Missed diagnosis is not uncommon and extensive local invasion in late cases may lead to very poor prognosis in patients treated by regular radical vulvectomy. Urethral involvement by vulvar cancer constitutes a special challenge to the gynecologic oncologists. The authors have developed an improved Gersuny-Lowsley's operation in addition to radical vulvectomy to preserve the function of urination and defecation after complete resection of the involved urethra. This modified procedure has been carried out in 10 patients with satisfactory functional control in 8 cases. A follow-up study for 1-10 years reveals no evidence of recurrence in all 10 cases.

The embryonal development of the human eye photoreceptors

The development of the photoreceptors of human embryos and fetuses dating from 7 weeks to term were studied. The outer segments of rods and cones began to form at the seventh month. The arrangement of the newly formed discs were not regular, but at term they were arranged parallel to each other and perpendicular to the long axes of the outer segments. At the 9th month, no phagosome containing discs was seen in the pigment epithelial cells, but they were discerned in those of the term fetuses.

Anti-idiotypic antibodies derived against C8, C9 and perforin bind homologous restriction factor

A pore-forming protein (PFP/perforin/cytolysin), stored in the cytoplasmic granules of cytolytic lymphocytes, lyses a variety of target cells but not the cytolytic lymphocytes. In the complement (C) system, a C8-binding protein (C8bp) or homologous restriction factor (HRF) has been described that protects cells against lysis mediated by homologous C. C8bp/HRF is known to bind to C8 and C9 and has also been suggested to protect lymphocytes against perforin-mediated lysis. Here, using an anti-idiotypic antibody approach, several polyclonal antisera were raised against IgGs that are specific for mouse perforin, and human C8 and C9. These anti-idiotypic antisera were shown to react against an overlapping epitope(s) on C8bp/HRF as indicated by the following evidence: (i) all three types of antisera reacted against partially purified C8bp/HRF and against a 65 kDa protein band in cell lysates; reactivity was only observed against disulfide-reduced antigens; (ii) the three antibodies react with a protein band in normal erythrocytes (E) but not with type III E of patients with paroxysmal nocturnal hemoglobinuria or with a mutant B lymphoblastoid cell line, both of which cell types are known to be deficient in C8bp/HRF; and (iii) the three antibodies compete with each other for binding to C8bp/HRF. Type III E and the C8bp/HRF-deficient mutant lymphoblastoid cell line, however, are as susceptible to perforin-mediated lysis as type I E and wild-type lymphoblastoid cell line, respectively, indicating that C8bp/HRF does not play a role in protecting cells against perforin-mediated lysis. These paradoxical findings suggest that perforin may share with C8 and C9 the same domain(s) that bind to C8bp/HRF and yet, unlike C8 and C9, perforin is not inactivated by this type of putative interaction. Since C8 and C9 are now readily available, the anti-idiotypic approach described here provides a convenient protocol for production of antisera specific for C8bp/HRF.

Resistance of cytolytic lymphocytes to perforin-mediated killing. Murine cytotoxic T lymphocytes and human natural killer cells do not contain functional soluble homologous restriction factor or other specific soluble protective factors

CTL and NK cells produce a cytolytic pore-forming protein (perforin, cytolysin) localized in their cytoplasmic granules. These cytotoxic cells are resistant to killing mediated by other lymphocytes and by purified perforin. A membrane factor, known as homologous restriction factor (HRF), has been suggested to confer protection to different cell types against both C- and perforin-mediated lysis. The granules of human large granular lymphocytes have been reported to contain, in addition to perforin, a soluble HRF activity that can be eluted from anion-exchange columns at 115 mM NaCl. Here, we report that a soluble HRF activity is absent in the granules or the cytosol of murine CTL and human NK cells. Our data indicate that the inhibition attributed to HRF could be explained by exogenous EDTA added during granule fractionation. EDTA was shown to bind to Mono Q and to elute at 90 to 120 mM NaCl. A second perforin-inhibitory activity was also eluted from such a column. However, it was present in preparations obtained not only from CTL and NK cells, but also from some perforin-susceptible tumor cell lines, indicating that it has nonrestricted distribution and suggesting that it is probably irrelevant to the perforin-protection mechanism. Our results argue against a role for soluble granule HRF or other soluble factors in mediating resistance of cytotoxic lymphocytes against perforin-mediated lysis.

Resistance of cytolytic lymphocytes to perforin-mediated killing. Murine cytotoxic T lymphocytes and human natural killer cells do not contain functional soluble homologous restriction factor or other specific soluble protective factors

CTL and NK cells produce a cytolytic pore-forming protein (perforin, cytolysin) localized in their cytoplasmic granules. These cytotoxic cells are resistant to killing mediated by other lymphocytes and by purified perforin. A membrane factor, known as homologous restriction factor (HRF), has been suggested to confer protection to different cell types against both C- and perforin-mediated lysis. The granules of human large granular lymphocytes have been reported to contain, in addition to perforin, a soluble HRF activity that can be eluted from anion-exchange columns at 115 mM NaCl. Here, we report that a soluble HRF activity is absent in the granules or the cytosol of murine CTL and human NK cells. Our data indicate that the inhibition attributed to HRF could be explained by exogenous EDTA added during granule fractionation. EDTA was shown to bind to Mono Q and to elute at 90 to 120 mM NaCl. A second perforin-inhibitory activity was also eluted from such a column. However, it was present in preparations obtained not only from CTL and NK cells, but also from some perforin-susceptible tumor cell lines, indicating that it has nonrestricted distribution and suggesting that it is probably irrelevant to the perforin-protection mechanism. Our results argue against a role for soluble granule HRF or other soluble factors in mediating resistance of cytotoxic lymphocytes against perforin-mediated lysis.

Differential susceptibility of type III erythrocytes of paroxysmal nocturnal hemoglobinuria to lysis mediated by complement and perforin

Previous reports have suggested that a 65 kDa membrane protein, termed homologous restriction factor (HRF), in addition to protecting erythrocytes (E) against lysis by homologous complement (C), may also be involved in protecting cytolytic lymphocytes against lysis mediated by a pore-forming protein (PFP/perforin), one of their own lytic mediators. Here, we used HRF-deficient type III E of patients with paroxysmal nocturnal hemoglobinuria (PNH) to study their susceptibility to lysis mediated by homologous C and perforin, and compared it with lysis of HRF-bearing control or PNH type I E. We show that type III E of PNH patients are indeed more susceptible to lysis mediated by homologous C than control or type I E, but they are as susceptible to perforin-mediated lysis as type I E. In addition, all human E (type I or III) tested here are equally susceptible to lysis mediated by either human (homologous) or murine (heterologous) perforin. By immunoblot analysis, we confirm that type III E, in contrast to type I E, were deficient in the 65 kDa HRF. These results support the notion that homologous species restriction is seen in the C- but not in the lymphocyte perforin-system and argue against an active participation of HRF in protecting cells from perforin-mediated lysis.

The lymphocyte pore-forming protein perforin is associated with granules by a pH-dependent mechanism

A pore-forming protein (PFP, perforin or cytolysin) has been found in the cytoplasmic granules of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. Extraction of granules with high-salt buffers or by freezing-and-thawing results in the release of perforin, which occurs only when the buffer pH is above 7.0. While high-salt extraction and freezing-and-thawing of granules at low pH (below 7.0) do not result in perforin release, these treatments render granules susceptible to a subsequent incubation with low-salt buffers (pH 7-8) that then solubilizes perforin completely. Granules may thus have been made leaky by high-salt extraction or freezing-and-thawing that may occur regardless of the buffer pH, while dissociation of perforin from granules may be exquisitely pH-sensitive. Freezing-and-thawing intact CTL and NK cells in physiological buffers with pH in the range of 7-8 (but not below 7) also causes release of perforin activity to the cell supernatant, thus providing a simple procedure by which perforin activity can be quantitated in small cell samples. Our results suggest that during lymphocyte-mediated killing, the extracellularly released perforin may rapidly dissociate from granules as a result of pH change and, in the process, become cytolytically active.

Resistance of cytolytic lymphocytes to perforin-mediated killing. Induction of resistance correlates with increase in cytotoxicity

CTL and NK cells cultured in vitro are known to produce a cytolytic pore-forming protein (PFP, perforin) localized in their cytoplasmic granules. Using purified perforin, we showed here that both cloned CTL and primary killer cell populations, including allospecific CTL, NK/lymphokine-activated killer cells, and MHC-non-restricted CTL, were more resistant to perforin-mediated killing than other lymphocyte populations and cell types. Similar results were obtained with both murine and human cytolytic lymphocyte populations. Resistance of killer cells to perforin correlated in general with their cytolytic capability. Thus, cells that have acquired competence to kill after stimulation with Con A, IL-2, or leukocyte-conditioned medium, were also the more resistant cells. IL-2-independent CTL lines and hybridomas derived in our laboratories could be triggered to become cytotoxic and perforin resistant by short-term stimulation with various cytokines, indicating that the acquisition of resistance to perforin-mediated lysis was independent of cell proliferation. Activation of one IL-2-independent CTL line with IL-2 also resulted in enhanced production of perforin and in enhanced serine esterase activity. The acquisition of cell resistance to perforin by these IL-2-independent cell lines after activation with stimulatory reagents was independent of protein and RNA neosynthesis: emetine, cycloheximide, and actinomycin D, while effectively blocking the incorporation of [35S]methionine into cell proteins, did not affect the induced increase in perforin resistance.