Whole-killed gp120-depleted HIV-1 antigen in a murine model for prophylactic vaccination.

In this study, the effects were examined of dose and adjuvant of whole-killed gp120-depleted HIV-1 antigen on antibody and cytokine responses in a murine model. Immunization with increasing doses of inactivated HIV-1 antigen in Incomplete Freund's Adjuvant (IFA) resulted in increased production of IL-4 and IgG1 antibody with decreased production of interferon gamma. Immunization with inactivated HIV-1 antigen in Detox PC adjuvant produced TH1 type predominant cytokine patterns along with IgG2a subclass antibody. Higher levels of interferon gamma were associated with immunization with inactivated HIV-1 antigen in Detox PC compared with inactivated HIV-1 in IFA or inactivated HIV-1 in saline. Inactivated HIV-1 antigen in Detox PC adjuvant produced a trend of lower levels of the beta-chemokine MIP-1 alpha compared with inactivated HIV-1 in IFA or saline. Dose and adjuvant play an important role in the type of immune response elicited to a whole-killed HIV vaccine. Low doses of inactivated HIV-1 antigen in Detox PC adjuvant are currently being studied in animal models in order to optimize cell-mediated immunity against HIV infection.

Initial studies on active immunization of HIV-infected subjects using a gp120-depleted HIV-1 Immunogen: long-term follow-up.

In 1987, exploratory clinical studies were initiated to determine whether the development of AIDS in HIV-infected individuals might be delayed or prevented by immunization with an inactivated HIV preparation. Preclinical studies had shown the preparation to be safe and immunogenic. Twenty-three patients with biopsy-confirmed persistent generalized lymphadenopathy (CDC III) and two with asymptomatic HIV infection and CD4 lymphocyte counts between 135 and 769/mm3 were studied, of whom eight (32%) had additional HIV-related symptoms. Over a 3-year period, they received a median of eight open-label inoculations of 100 micrograms of inactivated gp 120-depleted HIV-1 Immunogen in incomplete Freund's adjuvant (IFA). Clinical, general laboratory, immunologic, and virologic parameters were followed for up to 6 years. No serious treatment-related adverse experiences were reported, nor was accelerated HIV disease progression seen. Twelve patients developed a delayed-type hypersensitivity response (HIV-DTH) to the immunogen and nine showed fourfold or greater increases in anti-p24 antibody titers. In the follow-up period, 10 of the 25 patients developed AIDS and one with Kaposi's sarcoma (KS) at baseline progressed. Of the 12 patients who became HIV-DTH-responsive, one developed an opportunistic infection (OI), occurring approximately 5 years from study onset, and subsequently died. One additional HIV-DTH responder developed KS. Of the 13 patients who remained HIV-DTH-nonresponsive, nine (69%) progressed to AIDS and seven of these have died. Differences were also observed in terms of HIV-DNA copy number, CD4 percentages, and anti-p24 antibody patterns between the HIV-DTH-responsive and -nonresponsive groups, suggesting a more favorable clinical course in the former. HIV-1 Immunogen in IFA appears to be safe and immunogenic. Further studies are indicated to determine clinical efficacy of the HIV Immunogen as well as the significance of the apparent correlation between HIV-DTH responsivity and a more favorable clinical course.

Induction of humoral and cellular immunity to simian immunodeficiency virus: what are the requirements for protection?

In an effort to produce a strong humoral and cellular immune response that might protect against simian immunodeficiency virus (SIV) infection, groups of five rhesus macaques each were immunized intramuscularly at 0, 2 and 6 months with 100 micrograms of an inactivated preparation of SIV/Delta B670 in either an oil-in-water emulsion with Ribi Detox, containing mycobacterial cell wall skeleton and monophosphoryl lipid A (CWS/MPL) (group A) or a water-in-oil emulsion with incomplete Freund's adjuvant, containing CWS/MPL for the first two injections (group B). Animals were challenged with 10-100 monkey ID50 of monkey-cell-grown SIVmac251 3 months after the last injection, along with a group of four unvaccinated controls. Group B animals demonstrated the strongest immune responses following immunization, including neutralizing antibody titres against the challenge virus ranging from 160 to 320 and SIV-specific ELISA titres ranging from 10(5)-10(6) on the day of challenge, as well as strong in vitro lymphoproliferative and interleukin-2 (IL-2) production responses to the immunogen. Neutralizing antibody was not detectable in group A animals, ELISA titres were lower (10(2)-10(4)), no in vitro lymphoproliferative responses were observed, and in vitro IL-2 production was less pronounced. No protection against challenge was observed in either group. Moreover, group B animals exhibited a more pronounced clinical response following challenge than either group A animals or controls, consisting of hyperthermia and a greater degree of lymphadenopathy on day 7, followed by hypothermia and generally higher levels of serum viraemia on day 14.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of autoimmunity and AIDS: prospects for therapeutic intervention.

The network theory of autoimmunity is presented with recent experimental data relevant to the understanding of the pathogenesis of AIDS. Schematically, effector T cells specific for self-antigens exist normally, but their activity is modulated and prevented by networks of regulatory T cells. As a result of mimicry between molecular components of microorganisms and self-antigens, autoimmune disease can be triggered by specific foreign pathogens which alter the state of activity of the network from suppression to activation. Conversely, by a procedure known as T-cell vaccination, autologous effector T cells re-injected after in vitro stimulation and attenuation may alter the state of the network from an activation to a suppression. Numerous observations are reviewed that support the concept of autoimmune activity in the destruction of non-infected T4 cells. Such activity is presumed to be triggered by an antigen of viral origin, the most likely, but not the only one, being the envelope protein gp 120. Based on this hypothesis, a T-cell vaccination procedure against effector T cells responsible for autoimmunopathic activity in HIV-seropositive patients is proposed, similar to the one known from experimental study of autoimmunity and presently being tested in human autoimmune diseases. Its purpose would be to prevent T-cell loss and the onset of immunodeficiency disease in HIV-seropositive patients. Apart from its potential therapeutic value, this procedure will have use as a therapeutic test from which insight will be gained about the immunopathogenesis of AIDS.

Can AIDS be prevented by T-cell vaccination?

T-cell vaccination as a specific prophylactic and therapeutic procedure has been shown to be effective in animal models of autoimmune disease. As autoimmunopathogenic components have been implicated in HIV infection, the authors propose a therapeutic test utilizing T-cell vaccination and suggest that AIDS could be prevented by such a procedure.

Platelet aggregating material (PAM) of two virally-transformed tumors: SV3T3 mouse fibroblast and PW20 rat renal sarcoma. Role of cell surface sialylation.

Platelets are required for certain experimental tumor metastases and several lines of tumor cells have been shown to aggregate platelets. We have extracted a sedimentable sialolipoprotein, platelet aggregating material (PAM) from the cell surface of SV40 transformed Balb C3T3 fibroblasts which aggregates heparinized PRP at 2.5 micrograms/ml via the release reaction, following a one minute lag period. A similar extract from non-transformed 3T3 cells has barely measurable activity at 40 micrograms/ml. Gel-filtered platelets (GFP) do not aggregate with PAM. However, PAM aggregation can be restored by addition of 5% plasma but not by fibrinogen. Two plasma components are required: a heat-labile complement component which is activated during the lag period; and a heat-stable factor which is required for platelet aggregation. The pathophysiologic significance of PAM has been examined in ten variant cell lines derived from a spontaneously metastatic renal cell sarcoma of rats, initially induced with polyoma virus (PW20 Wistar-Furth parental lines). These lines were selected in vitro and in vivo from a single line and differed in their capacity to form distant tumors in various organs after subcutaneous injection. These cells were examined for cell surface sialylation, PAM and PAM sialic acid content, since cell surface sialic acid is increased in a variety of tumor tissues and PAM is inhibited by neuraminidase. A good correlation was obtained between in vivo metastatic potential and cell surface sialic acid, r = 0.83, p less than 0.003; cell surface sialic acid and PAM, r = 0.85, p less than 0.002; in vivo metastatic potential and sialic acid content of PAM, r = 0.69, p less than 0.03; and in vivo metastatic potential and PAM, r = 0.68, p less than 0.03. We conclude that platelets may play a role in hematogenous metastasis via the ability of tumor cells to aggregate platelets by cell surface constituents containing sialic acid. The platelet-tumor cell interaction requires activation of the alternate complement pathway and a heat stable plasma factor.

Metastatic potential is positively correlated with cell surface sialylation of cultured murine tumor cell lines.

The ability of murine tumor cells to metastasize spontaneously from subcutaneous sites is positively correlated with the total sialic acid content of the cells in culture, the degree to which the sialic acid is exposed on the tumor cell surface, and, most strongly, with the degree of sialylation of galactosyl and N-acetylgalactosaminyl residues in cell surface glycoconjugates. These findings suggest that sialic acid on the cell surface may play a role in tumor cell metastasis.

Theoretical considerations and practical concerns regarding the use of continuous cell lines in the production of biologics.

The origin and history of continuous cell lines are discussed briefly in the context of their biological relationship to diploid and tumorigenic cells. The question of the potential tumorigenicity of continuous cell lines is examined from the points of view of the theoretical risks involved in the use of these cells for the production of biological products, and of practical approaches to risk assessment. Animal and in vitro tumorigenicity test systems are discussed, and published data on the transfer of tumorigenic properties by DNA are reviewed. Both animal and human experience with vaccines produced in tumor cells is discussed in relation to cancer risk. When the theoretical risks of using continuous cell lines as substrates to produce biological products are balanced against the available data, it would appear reasonable to proceed with the use of such cell lines for the development of biologics because the benefits of those products appear to exceed by far the potential risks associated with the use of these cell substrates.

Detection and elimination of cellular nucleic acids in biologicals produced on continuous cell lines.

Experiments have been conducted to determine the extent to which currently available purification techniques can remove contaminating substrate cellular DNA from inactivated poliovirus vaccine produced on continuous cell lines rising highly [32P]-labeled, nick-translated cellular DNA added to poliovirus suspensions, we found that purification procedures were capable, in small-scale experiments, of reducing contaminating DNA by factors of 10(3) (DNAse treatment followed by gel filtration) and 10(3)-3X10(5) (ion exchange chromatography). Sequential application of these purification steps should reduce contaminating cellular DNA to acceptable levels. We also examined the potential usefulness of immobilized nucleic acid hybridization techniques for the routine direct testing of residual cellular nucleic acids in final production lots of inactivated poliovirus vaccine and other biologicals. A filter hybridization test, using [32P]-labeled, nick-translated cellular DNA as a probe, was capable of detecting 40 pg of homologous cellular DNA. Using probes of higher specific activity the assay should be sensitive enough for use in routine quality control.

Correlation between spontaneous metastatic potential, platelet-aggregating activity of cell surface extracts, and cell surface sialylation in 10 metastatic-variant derivatives of a rat renal sarcoma cell line.

Several properties of 10 cell lines derived from the polyoma-induced PW20 Wistar-Furth rat renal sarcoma have been examined, including the ability of the tumor cells to metastasize spontaneously from subcutaneous sites in syngeneic hosts, the platelet-aggregating activity of material extracted by urea from the surface of cultured cells, the sialic acid content of the platelet-aggregating material, and the degree of sialylation of cell surface glycoconjugates in cultured cells. A correlation has been observed among all of these parameters. The results suggest a possible link between the degree of cell surface sialylation of tumor cells, their ability to aggregate platelets, and their ability to metastasize.