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PubMed1990

Effect of iscoms and their adjuvant moiety (matrix) on the initial proliferation and IL-2 responses: comparison of spleen cells from mice inoculated with iscoms and/or matrix.

In the iscom, antigen is attached by hydrophobic interactions to a matrix which is built up by the adjuvant Quil A and lipids. Thus, the iscom presents antigen in multiple copies on a small particle with a built-in adjuvant. By studying the specific antibody response, in vitro proliferation and IL-2 secretion by splenocytes from mice following different in vivo treatments with iscoms and/or matrix, we attempted to distinguish between nonspecific stimulatory effects, caused by the matrix or iscoms, and specific responses to the antigens incorporated into iscoms. The results strongly suggest that matrix and also iscoms exert a nonspecific adjuvant activity by a transient high spontaneous proliferation of cells collected within 2 weeks after administration of iscoms or matrix. This high rate of proliferation was preceded by suppressed proliferation, 3 days after injection with matrix or iscom. The adjuvant component included in iscoms, i.e., the matrix, does not excert a mitogenic stimulation in vitro or influence the levels of specific antibodies in serum. Specific responses to the antigens included in iscoms were recorded both as increasing levels of serum antibodies and as iscom-induced proliferation of immune spleen cells in vitro. The recruitment of IL-2 was only related to the specific stimulation induced by the antigens in iscom.

Adjuvants, Immunologic↗

PubMed1995

Isolation and quantification of Quillaja saponaria Molina saponins and lipids in iscom-matrix and iscoms.

In the iscom, multiple copies of antigen are attached by hydrophobic interaction to a matrix which is built up by Quillaja triterpenoid saponins and lipids. Thus, the iscom presents antigen in multimeric form in a small particle with a built-in adjuvant resulting in a highly immunogenic antigen formulation. We have designed a chloroform-methanol-water extraction procedure to isolate the triterpenoid saponins and lipids incorporated into iscom-matrix and iscoms. The triterpenoids in the triterpenoid phase were quantitated using orcinol sulfuric acid detecting their carbohydrate chains and by HPLC. The cholesterol and phosphatidylcholine in the lipid phase were quantitated by HPLC and a commercial colorimetric method for the cholesterol. The quantitative methods showed an almost total separation and recovery of triterpenoids and lipids in their respective phases, while protein was detected in all phases after extraction. The protein content was determined by the method of Lowry and by amino acid analysis. Amino acid analysis was shown to be the reliable method of the two to quantitate proteins in iscoms. In conclusion, simple, reproducible and efficient procedures have been designed to isolate and quantitate the triterpenoids and lipids added for preparation of iscom-matrix and iscoms. The procedures described should also be useful to adequately define constituents in prospective vaccines.

Adjuvants, Immunologic↗

PubMed1999

Iscom and iscom-matrix enhance by intranasal route the IgA responses to OVA and rCTB in local and remote mucosal secretions.

Iscoms, with rCTB incorporated via the GM1 receptor, enhanced in mice the mucosal immunogenicity of rCTB as antigen after intranasal (i.n.) administration both by inducing IgA response in the remote intestinal tract mucosa and by a 100-fold increase of the specific IgA locally in the lungs. Iscom-matrix as a separate entity mixed with rCTB enhanced the rCTB-IgA response similarly. While OVA in iscoms induced high mucosal IgA responses, iscom-matrix co-administered with OVA induced low or no mucosal IgA response to OVA. A synergism between iscoms and rCTB could only be seen as an adjuvant targeting effect enhancing the IgA response to OVA in the remote genital tract mucosa. In serum, the immunomodulatory effect of iscoms after i.n. administration was seen as an enhanced serum IgG2a response.

Adjuvants, Immunologic↗

PubMed1988

Canine distemper virus (CDV) immune-stimulating complexes (Iscoms), but not measles virus iscoms, protect dogs against CDV infection.

The potential of immune-stimulating complexes (iscoms), a novel form of antigenic presentation, for the induction of protective immunity against morbillivirus infection was shown by immunizing dogs with canine distemper virus (CDV) iscoms, which contained the fusion (F) protein and a minor amount of the haemagglutinin of the virus. The immunized dogs developed CDV-neutralizing antibodies but, in contrast to non-immunized dogs, did not develop viraemia or clinical signs of infection upon intranasal challenge with the virulent Snyder Hill strain of CDV. Immunization of dogs with measles virus (MV) iscoms, prepared either from affinity-purified MV F protein or from purified whole virus, resulted in partial protection against challenge with CDV. The data presented clearly show that the iscom form of antigenic presentation may be considered a serious candidate for subunit vaccines against morbillivirus infection.

Adjuvants, Immunologic↗

PubMed1992

Incorporation of soluble antigens into ISCOMs: HIV gp120 ISCOMs induce virus neutralizing antibodies.

Through a process of covalent attachment of palmitic acid, we have incorporated recombinant gp120 of HIV strain IIIB into ISCOMs. Rabbits immunized with ISCOMs incorporating 10 micrograms gp120 produced high levels of gp120-specific antibody, comparable to the response to ten times as much antigen in complete Freund's adjuvant. The ISCOM-induced antisera showed virus neutralizing activity against the homologous strain, but failed to neutralize two heterologous strains of HIV-1. The antisera recognized non-conformationally determined epitopes on gp120, and antibody binding to gp120 was affected by glycosylation of the viral glycoprotein.

AIDS Vaccines↗

PubMed1998

Internalization of iscom-borne antigens and presentation under MHC class I or class II restriction.

Exogenous nonreplicating antigens (Ag) incorporated into immunostimulating complexes (iscoms) induce CTL responses under MHC class I restriction. A requirement for inducing CTL responses is that the Ag is delivered to the cytosol of antigen-presenting cells (APC), a route restricted to endogenously produced Ag. To investigate the mechanisms by which iscoms elicit MHC class I-restricted responses, the intracellular distribution of influenza virus envelope proteins incorporated in iscoms (flu-iscoms) or in micelles (flumicelles) was studied in vitro using murine peritoneal cells (PEC). Ultrathin sections of cells pulsed with biotinylated flu-iscoms or flu-micelles were analyzed by electron microscopy after detection of the biotin label by reaction with streptavidin-gold. PEC pulsed with flu-iscoms showed a pattern of scattered gold particles distributed in clear and dense vesicles as well as in the intracellular space but not associated with organelles. In cells pulsed with flu-micelles, Ag was also detected in most cellular compartments but at a considerably lower concentration. The intracellular distribution of particulate Ag in iscom or micelle form was confirmed by lysis and differential centrifugation of Ag-pulsed APC. Furthermore, P815 cells pulsed with flu-iscoms were lysed by specific immune effectors showing that the iscom-Ag was processed and presented by class I-expressing APC. Flu-iscoms were internalized about 50-fold more efficiently than ovalbumin iscoms (ovaiscoms) suggesting that the nature of the protein and/or the presence of cellular receptors are important factors influencing the capacity of APC to take up iscom-borne proteins. PEC accounted for the most active internalization of iscom-borne Ag, although splenic dendritic cells and B cells also took up fluiscoms with remarkable efficiency.

Animals↗

PubMed2000

Induction of antibody and T-cell responses by immunization with ISCOMS containing the 38-kilodalton protein of Mycobacterium tuberculosis.

In this study, we investigated the influence of different amounts of N-(palmitoyloxy) succinimide (PA-NHS): attachment of lipid tails to the protein and Quil A on the immunogenicity of the 38-kDa mycobacterial protein incorporated into immunostimulating complexes (ISCOMS; 38-kDa ISCOMS). The addition of higher amounts of Quil A during the ISCOMS preparation increased the amount of protein incorporated into ISCOMS, whereas the use of higher amounts of PA did not influence this parameter. Low antibody responses were observed after primary immunization with all 38-kDa ISCOMS preparations which, however, strongly increased after booster injections. IgG2a is the major subclass IgG induced by these ISCOMS preparations. There were only slight differences between the various ISCOMS formulations in their capacity to induce cytotoxic T-lymphocytes (CTLs). Spleen cells primed with ISCOMS prepared with the highest amount of Quil A produced high levels of IFN-gamma after stimulation with T helper cell type one (Th1) peptide of the 38-kDa protein (aa 70-84), 38-kDa protein or purified protein derivate (PPD). Spleen cells primed with ISCOMS prepared with the lowest amount of Quil A only substantial IFN-gamma levels were detected after stimulation with 38-kDa protein. IL-4 secretion was very low or not detectable with all ISCOM preparations. These results therefore demonstrated that all 38 kDa-ISCOMS preparations were: (1) immunogenic by inducing antibodies, Th1 and CTL responses; (2) that the way in which the ISCOMS were prepared, e.g. the amount of Quil A used, modulates the epitope specificity of the Th1 response.

Adjuvants, Immunologic↗

PubMed1999

Immunomodulation by iscoms, immune stimulating complexes.

The iscom is a uniform stable complex consisting of cholesterol, phospholipid, adjuvant-active saponin, and antigen. The iscom matrix is a particulate complex with identical composition, shape, and morphology, but lacking the incorporated antigen. The assembly of the complex is based on hydrophobic interactions, but antigens that are not hydrophobic can be conjugated with a hydrophobic tail or hidden hydrophobic regions can be exposed, e.g., by acid treatment, to facilitate the incorporation into iscoms. The functional aspects of iscoms are described emphasizing immunomodulation in mouse models. Iscoms prominently enhance the antigen targeting, uptake, and activity of antigen presenting cells including dendritic and B cells and macrophages resulting in the production of proinflammatory cytokines, above all interleukin (IL)-1, IL-6, and IL-12. The expression of costimulatory molecules major histocompatibility complex (MHC) class II, B7.1 and B7.2, is also enhanced. The latter partly explains why the iscom is an efficient adjuvant for elderly mice. Iscoms enhance the Th1 type of response with increased production of IL-2 and interferon gamma. However, with some antigens and particularly in monkeys immunized with HIV iscoms, the production of IL-4 was enhanced. IL-4, IL-2, and interferon gamma (IFNgamma) together with the beta chemokines MIP-1alpha and MIP-1beta correlated with protection against challenge infection with a chimeric virus (simian immunodeficiency virus-human immunodeficiency virus). Iscoms were also shown to induce a potent immune response in the newborn and to be an efficient delivery system for mucosal administration. Technical information is given about formulation of iscoms and about handling of antigens to optimize their incorporation into iscoms.

Adjuvants, Immunologic↗

PubMed2001

Immunostimulating complexes (ISCOMs) for nasal vaccination.

The immunostimulating complex (ISCOM) is documented as a strong adjuvant and delivery system for parenteral immunization. Its effectiveness for mucosal immunization has also been proven with various incorporated antigens. Lövgren et al. were the first to demonstrate the capacity of influenza virus ISCOMs to induce mucosal immune response and protection after one comparatively low nasal dose. Further studies show that similar to Cholera toxin (CT) and Escherichia coli heat-labile toxin (LT), ISCOMs break immunological tolerance and exert strong mucosal adjuvant activity, resulting in secretory IgA and systemic immune responses. Striking is the capacity of ISCOMs to induce CTL response also after nasal administration. In contrast to CT, ISCOMs initiate mucosal as well as systemic immune responses in an IL-12 dependent manner but independently of IL-4. The recombinant B subunit of cholera toxin (rCTB) was incorporated in the same ISCOM particle to explore symbiotic effects. The IgA response to rCTB in lungs was increased 100-fold when rCTB was administered nasally in ISCOMs and more than 10-fold in the remote mucosa of the genital tract. An enhanced IgA response to a passenger antigen OVA was recorded in the remote genital tract. After i.n. administration of the envelope proteins of respiratory syncytial virus in ISCOMs, high serum antibodies were induced, almost at the same levels as those following parenteral immunization and potent IgA responses were also evoked both at the local respiratory mucosa, and in the cases tested at the distant mucosae of the genital and intestinal tracts. Similar results have also been recorded with ISCOMs containing envelope proteins from Herpes simplex virus, Influenza virus and Mycoplasma mycoides. The mucosal targeting property of envelope proteins of RSV was utilized in an HIV-gp120 RSV ISCOM formulation. After nasal administration an enhanced mucosal IgA response to gp120 was observed in the female reproductive tract. In general, antigens derived from envelope viruses or cell membranes incorporated into ISCOMs retain their biological activity and conformation, encompassing the mucosal targeting and virus neutralizing properties.

Adjuvants, Immunologic↗

PubMed1996

Induction of homologous virus neutralizing antibodies in guinea-pigs immunized with two human immunodeficiency virus type 1 glycoprotein gp120-iscom preparations. A comparison with other adjuvant systems.

The immunogenicity in guinea-pigs of the human immunodeficiency virus type 1 envelope glycoprotein gp120 in immune stimulating complex (iscom) was compared to that of gp120 adjuvanted with QuilA-matrix (iscom without attached antigen), aluminium hydroxide (alum) and the Ribi adjuvant system. Gp120 was either incorporated into iscoms by covalent conjugation (iscom(c)) or by acid treatment of gp120 (iscom(a) and both these preparations induced high ELISA antibody titres to gp120. Virus neutralizing (VN) antibodies were most frequently induced by gp120 in iscom(c), iscom(a) or in alum and correlated to high titres to the V3-region of gp120. Further, antibodies induced by gp120-iscom(c) most efficiently inhibited binding of a VN monoclonal antibody GP13 to the CD4 binding region of gp120 whereas gp120-iscom(a) induced the highest mean titre of antibodies blocking the binding of [125I]gp120 to CD4. These results suggest that the gp120-iscom preparations efficiently induced high levels of gp120 specific antibodies and that the adjuvant formulation of gp120 affect the specificity and functional properties of elicited antibodies.

Adjuvants, Immunologic↗

PubMed2000

Introduction of the haemagglutinin transmembrane region in the influenza virus matrix protein facilitates its incorporation into ISCOM and activation of specific CD8(+) cytotoxic T lymphocytes.

The gene encoding the influenza virus A matrix (MA) protein was cloned into the bacterial expression vector pMalC with and without the sequence encoding the transmembrane region of the haemagglutinin (HA). With the resulting recombinant proteins, immune stimulating complexes (ISCOM) were prepared. The MA protein with the hydrophobic anchor region (rMAHA) associated more efficiently with ISCOM than the unmodified MA protein (rMA). A B-lymphoblastoid cell line (B-LCL) was lysed by an autologous CD8(+) cytotoxic T lymphocyte (CTL) clone specific for the MA protein after incubation with rMAHA-ISCOM but not after incubation with rMA, rMAHA, rMA-ISCOM or empty ISCOM. The B-LCL was also lysed by the CTL clone after incubation with empty ISCOM mixed with the respective MA proteins. Incubation of ISCOM with the rMAHA protein proved to be the most efficient in this respect. Addition of the proteasome inhibitors lactacystin or clasto-lactacystin beta-lactone to the B-LCL incubated with rMAHA-ISCOM or the MA proteins mixed with empty ISCOM dramatically decreased the lysis by the CD8(+) CTL clone. These results indicate that the addition of a hydrophobic anchor to hydrophilic proteins in combination with ISCOM facilitates their entry in the MHC class I processing and presentation pathway. This may be an attractive approach for the development of subunit vaccines aiming at the induction of CTL-mediated immunity.

Antigen Presentation↗

PubMed1991

On the structure of immune-stimulating saponin-lipid complexes (iscoms).

Immune-stimulating complexes (iscoms) are stable complexes of cholesterol, phospholipid and Quil A, a triterpene saponin mixture in the size range from 40 to 100 nm. They can be used as antigen carriers in subunit vaccines. In this paper it is demonstrated that iscoms are rigid, negatively charged vesicles in which small water soluble molecules like carboxyfluorescein cannot be retained. The negative zeta-potential prevents iscoms from aggregation. The chemical composition of iscoms in one dispersion varied considerably. A typical example of the composition of iscoms is cholesterol/phospholipid/Quil A = 1.0:1.2:6.2 by weight for the iscom matrix, that is iscoms without antigen, and 1.0:1.3:5.1 for antigen-containing iscoms. A hypothetical model for the structure of the iscom matrix and related structures is presented, based on analytical chemical, physico-chemical and electronmicroscopic data. In this model iscoms are considered to be multi-micellar structures, shaped and stabilized by hydrophobic interactions, electrostatic repulsion, steric factors and possibly hydrogen bonds. The individual micelles are relatively flat, ring-shaped structures, the center offering space for one of the two bulky sugar chains of the saponins.

Adjuvants, Immunologic↗

PubMed1989

Bovine leukaemia virus ISCOMs: biochemical characterization.

The glycoprotein gp51 of bovine leukaemia virus (BLV) has been included in an immunostimulating complex (ISCOM). The ISCOM was characterized biochemically in SDS-polyacrylamide gel electrophoresis showing the presence of proteins of estimated molecular weights of 50 and 30 kDa. Immunoblotting showed that gp51 was present in the ISCOM. The BLV-ISCOM had a S-value of 19 S and the electronmicrograph showed the cage-like structure as previously reported for other ISCOMs. About 17% of the total amount of gp51 in the cell culture fluid was recovered in the ISCOMs. The largest loss of gp51 was encountered during the sedimentation of the virus. An ELISA, utilizing monoclonal antibodies to defined epitopes for capture was developed to control the antigenicity of epitopes, e.g. those known to induce neutralizing antibodies. Using this device as a quality control for epitopes the following could be stated. First, ISCOMs prepared from virus solubilized with the non-ionic detergents Triton X-100 or MEGA did not react with neutralizing monoclonal antibodies. In contrast, ISCOMs prepared from virus solubilized with the non-ionic detergents Tween-20, Tween-80 or octyl glucoside did react with the neutralizing antibodies. Second, the neutralizing epitopes were better exposed in ISCOMs than the other epitopes of gp51. In a preliminary experiment it was shown that gp51 in ISCOMs was highly immunogenic.

Adjuvants, Immunologic↗

PubMed1989

Iscom of viral envelope proteins protects against Aujeszky's disease.

An immunostimulating complex (iscom) containing the envelope proteins of pseudorabies virus (PRV) was prepared and its efficacy was evaluated in two experiments on sheep. In the first experiment, sheep were intramuscularly (i.m.) or intradermally (i.d.) vaccinated with PRV iscom doses varying between 1 and 81 micrograms. The vaccination was repeated on Day 21 and the animals were exposed to challenge infection by subcutaneous inoculation of 1000 TCID50 of the virulent Phylaxia strain on Day 35 after first vaccination. In the second experiment, sheep were i.m. vaccinated with single doses of iscom varying between 1 and 27 micrograms and challenge-infected on Day 14. It was found that: (1) the i.d. administration of PRV iscom has no advantage over i.m. administration (2); a single dose of greater than or equal to 3 micrograms of PRV iscom provided protection against the disease. In immunoblots, viral proteins of molecular masses 120, 109, 55, 53 and 32 kDa were detected with the sera obtained from iscom-vaccinated and subsequently challenge-infected sheep, but not with sera from sheep which were iscom-vaccinated only. The above findings indicated that: (1) by using iscom technology, potent subunit vaccines can be prepared to prevent Aujeszky's disease; (2) the selective incorporation of viral envelope proteins into iscoms gives the opportunity to discriminate between iscom-vaccinated and naturally infected animals.

Adjuvants, Immunologic↗

PubMed1988

Measles virus fusion protein presented in an immune-stimulating complex (iscom) induces haemolysis-inhibiting and fusion-inhibiting antibodies, virus-specific T cells and protection in mice.

Immune-stimulating complexes (iscoms), which have recently been shown to be highly effective for the antigenic presentation of membrane proteins of viruses, were prepared with affinity-purified fusion (F) protein of measles virus (MV), using an adaptation of the standard method for iscom preparation. Immunization of monkeys with the F iscom preparation induced biologically active anti-F protein antibodies as was shown in haemolysis inhibition and cell-cell fusion inhibition tests. A whole MV iscom preparation, which also contained the haemagglutinin protein, induced not only also haemolysis-inhibiting antibodies, but, in contrast to the F iscom preparation, also haemagglutination-inhibiting and virus-neutralizing antibodies. In addition the F iscom preparation was shown to activate measles virus-specific T cells in mice. This was demonstrated by the generation of an MV-specific delayed type hypersensitivity response in F iscom-immunized animals and by the isolation of T cell clones specific for MV F protein with the T helper phenotype. Vaccination of mice with MV iscom or F iscom protected them from MV-induced fatal encephalopathy. The data concerning the immunogenicity of MV proteins presented in iscoms are discussed in relation to their potential for the development of an inactivated measles vaccine.

Animals↗

PubMed1996

Adjuvant activity of iscoms; effect of ratio and co-incorporation of antigen and adjuvant.

We have studied the importance of co-incorporation of antigen and adjuvant in iscoms and the effects of different ratios of adjuvant and antigen in the iscom particles. Immune responses to influenza virus antigens (flu-Ag) in iscoms were compared to those induced by flu-Ag mixed with iscom-matrix, i.e. antigen and adjuvant delivered in separate packages. Higher doses of Quil A were required with iscom-matrix to induce strong immune responses compared to iscoms containing the same amount of antigen. The immunogenic properties of iscoms were affected by the ratio between antigen and adjuvant in the particles. Both iscoms and flu-Ag mixed with iscom-matrix induced antigen-specific antibodies with similar IgG subclass distribution and activated spleen cells producing high levels of IL-2 and IFN-gamma in vitro.

Adjuvants, Immunologic↗

PubMed1998

The immunostimulating complex (ISCOM) is an efficient mucosal delivery system for respiratory syncytial virus (RSV) envelope antigens inducing high local and systemic antibody responses.

ISCOM is an efficient mucosal delivery system for RSV envelope proteins as measured by antibody responses in respiratory tract secretions and in sera of mice following two intranasal (i.n.) administrations. Intranasally administered RSV ISCOMs induced high levels of IgA antibodies both in the upper respiratory tract and in the lungs. In the lungs, a prominent and long-lasting IgA response was recorded, which still persisted 22 weeks after the second i.n. immunization when the experiment ended. Subcutaneous (s.c.) immunization only induced low IgA titres in the upper respiratory tract and no measurable response to RSV was found in the lungs. Differences were also noticed in serum between the i.n. and s.c. modes of immunization. ISCOMs given intranasally induced earlier, higher and longer lasting IgM and IgG1 serum anti-RSV antibody responses than those induced by the s.c. mode of administration. A low serum IgE response was only detectable at 2 weeks after i.n. immunization with ISCOMs and after s.c. immunization with an inactivated virus, but no IgE response was detectable after s.c. injection of ISCOMs. The serum IgA response was more pronounced following s.c. injection of inactivated virus than after i.n. application of ISCOMs, and a clear-cut booster effect was obtained with a second immunization. Virtually no serum IgA response was detected after the s.c. administration of ISCOMs. In conclusion, the high immune responses induced by RSV ISCOMs in the respiratory tract and serum after i.n. administration indicate prominent mucosal delivery and adjuvant properties of the ISCOMs, warranting further studies.

Administration, Intranasal↗

PubMed1997

Influence of Quillaja saponaria triterpenoid content on the immunomodulatory capacity of Epstein-Barr virus iscoms.

The immune responses to immunostimulating complexes (iscoms) containing recombinant Epstein-Barr virus (EBV) gp340 envelope protein was evaluated in BALB/c (H-2(d)) and CBA (H-2(k)) mice. Gp340-iscoms were used either with a low content of Quillaja triterpenoid adjuvant (L-iscoms) or supplemented with additional Quillaja adjuvant in the form of iscomatrix (S-iscoms). Class and subclass distribution of anti-gp340 antibodies, EBV-neutralizing antibodies, antigen-specific T cell proliferation and cytokine production were determined and these results compared to those obtained by immunization with non-adjuvated gp340. The H-2(d) and H-2(k) mice were characterized as low or high responders in respect to the level of specific anti-gp340 antibodies, secretion of IgG2a isotype, antigen-specific lymphoproliferative capacity, interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) production in the basic immunizations with gp340. While presentation of the antigen in iscom formulations with low levels of Quillaja triterpenoids induces a moderate enhancement of the immune responses in the low responder H-2(d) mice, supplementation with high levels of iscomatrix immunomodulator was required to enhance the immune responses in the high responder H-2(k) mice. In both mouse strains subcutaneous immunization with S-iscoms resulted in a significant increase of IgG1- and IgG2a-specific antibodies, as well as in strong antigen-specific proliferative response confirmed by the simultaneous cytokine production. The enhanced antigen-specific secretion of IL-2 and IFN-gamma together with the abrogation of IL-10 and the absence of IL-4 indicates that the responses were driven towards a Th1-type rather than Th2-type immune response. The S-iscom formulations minimized the differences in immune responses between the two mouse strains, but the capacity of immune sera to neutralize EBV transformation in vitro remained completely strain-dependent. These data indicate that immune responses generated by iscoms can be manipulated by altering the triterpenoid composition of the iscoms and that the levels of triterpenoids can determine whether or not a Th1-type response is made.

Adjuvants, Immunologic↗