Effects of structural variations in synthetic glycolipids upon mitogenicity for spleen lymphocytes, adjuvancy for humoral immune response and on anti-tumour potential

Modulation of amphotericin B activity by association with mannose ester

The biological and molecular properties of a new formulation of Amphotericin B complexed with the surfactant palmitoyl mannose were studied in in vitro as well as in in vivo situations. The properties analyzed include toxicity towards two types of mammalian cells and four fungi strains, effect on macrophage activity, inflammatory properties, acute toxicity in mice and spectral behavior in presence of foetal calf serum or 6% propanol. The results demonstrate that, in presence of palmitoyl mannose, the cytotoxicity of AmB is decreased towards both, fungal and mammalian cells while its fungistatic potential is increased, its inflammatory properties are conserved and its acute toxicity is significantly diminished. These effects can be potentially explained by the formation of a complex between AmB and the sugar ester that impedes the interaction of the drug with either serum components or cell membrane constituents. The overall properties of AmB in the complex would be expected to favor an increase in the immunoadjuvant properties of the drug, a more localized inflammation during fungal infection and consequently a better therapeutic efficiency.

Stimulation of lymphoproliferation by sucrose esters

Lauryl sucrose has recently been shown to decrease the toxicity of amphotericin B (AmB), a widely used antifungal agent, probably through a modulation of its physical state. In this paper, we demonstrate using a lymphoproliferative assay, that lauryl sucrose and monosubstituted analogs in addition to their effects on AmB also possess significant immune enhancer properties. An anti-bell shape relationship was observed between stimulation of lymphoproliferation and chain length of ester's fatty acid, lauryl sucrose being the less active of the tested derivatives. These properties of sucrose esters are discussed in the specific context of antifungal therapy.

Mitogenic, immunoadjuvancy, and genetic studies on fatty acyl maltose

Three synthetic glycolipids, maltose tetrapalmitate (MTP), maltose hexastearate (MHS), and maltose hexalinoleate (MHL) prepared as nontoxic lipid A analogs, and Escherichia coli lipopolysaccharide (LPS) were assayed for their mitogenic activity using spleen lymphocytes in nine inbred mouse strains and three F1 hybrids. The MTP and LPS were also assayed for their ability to enhance plaque-forming cell (PFC) responses using sheep red blood cells as the antigen in the same inbred mouse strains and F1 hybrids, The mitogenic activity of synthetic glyco-lipids was several fold lower than that of LPS and MHL was inferior to MTP and MHS. DBA/2J was the most responsive strain for MTP and DBA/1J and C3H/HeJ the least. The mitogenic activity of MTP was generally in agreement with the PFC response stimulation by it. Low-dose cyclophosphamide treatment of mice synergized MTP for PFC response augmentation. Genetic studies on MTP mitogenicity revealed that 90% of responder DBA/2J X nonresponder C3H/HeJ F1 hybrids had intermediate mitogenic activity. Among F2, 73% had intermediate-high activity and 27% were nonmitogenic. Among F1 X C3H/HeJ backcrosses 11% had high, 56% intermediate, and 33% had no mitogenic activity, whereas, for the F1 X DBA/2J backcross, 14% had high, 36% intermediate, and 50% low or negligible activity. The data favored a single gene for MTP activation of immune cells.

Synthetic sulpholipopolysaccharides: novel adjuvants for humoral immune responses

Referring to the strong immunostimulating activity of combinations of lipophilic agents and dextran sulphate, conjugates with chemical determinants of both types of adjuvants were synthesized and then examined for immunostimulatory capabilities in mice. Saturated fatty acids with varying chain lengths and sulphate groups were coupled covalently at defined ratios to the polysaccharide Ficoll (MW 400,000). Chemical analysis of 60 of the sulpholipopolysaccharides synthesized revealed that the number of sulphate groups per monosaccharide unit varied from 0 to 1.6, and the number of lipid groups from 0 to 0.8. Adjuvanticity of these conjugates for the humoral immune response was determined using sheep red blood cells (SRBC) and dinitrophenyl-haptenated bovine serum albumin (DNP-BSA) as antigens. Five days after intraperitoneal injection of adjuvant and antigen, the numbers of direct anti-SRBC plaque-forming cells (PFC) in the spleen were determined. Anti-DNP antibody titres were measured from 1 to 4 weeks after immunization. PFC responses to 2 X 10(6) SRBC were augmented up to a 100-fold by conjugates of Ficoll and sulphate (sulphopolysaccharides: SPs) or lipid groups (lipopolysaccharides: LPs). Introduction of low or moderate numbers of lipid groups in SPs reduced adjuvanticity. Adjuvant activity of sulpholipopolysaccharides (SLPs) with varying sulphate and high lipid content depended on the sulphate contents and the chain length of the lipids. Sulphate reduced adjuvanticity of the SLPs, and the number of sulphate groups required for complete annihilation increased with the chain length of the lipid. LPs and SLPs, including conjugates that did not enhance anti-SRBC PFC responses, augmented serum antibody responses to DNP-BSA while SPs were hardly effective.

Combination of 60Co gamma-radiation, misonidazole, and maltose tetrapalmitate in the treatment of Dunning prostatic tumor in the rat

Maltose tetrapalmitate (MTP), a synthetic nontoxic immunoadjuvant, the radiosensitizer misonidazole (MISO), and 60Co gamma-radiation, alone or in combination, were used in the management of Dunning prostatic tumor in the rat. Nine groups of 10 rats each were used to assess the efficacy of various therapeutic modalities. Tumor growth rates and animal survival times were determined for each group. Radiation was more effective when combined with MTP, but the adjuvant must be present when radiation is given for synergism to occur. MISO was as effective as MTP when used with radiation, but combining them cancels out their individual effects. In a clinical situation it would be advantageous to use separately the synergisms existing between MISO and radiation on the one hand and MTP and radiation on the other hand.

Modulation of the immunosuppressive effects of splenic macrophages in Fischer rats bearing adenocarcinoma 13762

The nature of spleen cells in Fischer rats bearing a large size (greater than 1 cm diameter) mammary adenocarcinoma 13762A (MAC) which block the immunostimulating capacities of MTP2 (a synthetic immunomodulator) and suppress proliferation in vitro of splenic T and B lymphocytes by their respective mitogens was investigated. Splenic macrophages were recognized as the suppressor cells by (a) restoration of mitogenic responses by depletion of macrophages from spleen cell suspensions and (b) continued suppressor activity in spleen cell suspensions of tumor bearers devoid of viable T lymphocytes. Macrophage contact with T lymphocytes was required for the inhibition of T lymphocyte proliferation by concanavalin A as shown by (a) the absence of suppressor activity in supernatants derived from cultured suppressor macrophages, (b) lowering of the suppressor activity of intact macrophages after treatment with neuraminidase, (c) lowering of the suppressor activity of macrophages by addition of red cells to spleen cultures of tumor bearers indicating red cell interference with macrophage-T cell interaction and (d) lack of inhibiting action of suppressor macrophages on allogenic T lymphocyte proliferation showing macrophage T cell recognition for suppression. Animals bearing a large size tumor exhibited spleen hypertrophy and an increase in macrophage: lymphocyte ratio and a decrease in red cell: lymphocyte ratio. Splenic macrophages did not appear to be implicated in blocking antitumor immunity induction since (a) suppressor macrophages were absent in spleens during the inductive phase of the immune response and (b) MAC implanted in allogenic Wistar rats grew to about 2 cm diameter, induced splenic suppressor macrophages but the tumor was later rejected by the animals. Collectively the results suggest that suppressor macrophages are the result of increasing tumor volume rather than its cause.

In vitro spleen cell proliferation following in vivo treatment with a synthetic glycolipid or lipid A in three mouse strains

Synthetic glycolipid, maltose hexastearate (MHS), like LPS or lipid A is a B cell mitogen for outbred Swiss mice, inbred C3H/HeN and C3H/HeJ X C3H/HeN F1 hybrid but not for C3H/HeJ mice. MHS administered i.p. (10 micrograms) to Swiss, C3H/HeN, C3H/HeJ and C3H/HeJ X C3H/HeN F1 hybrid mice confers within 90 min an increased ability in the spleen cell populations such that they exhibit increased incorporation of 3H thymidine into cellular DNA in vitro. The spleen cells of MHS treated mice also respond in vitro more vigorously than controls to a T cell mitogen (Con A) but not at all differently from controls to a B cell mitogen (LPS). The stimulated cells are sensitive to anti theta serum + C' (experiment done with Swiss mice) and the Lyt 1,1 monoclonal antibody + C' (experiment done with C3H/HeN mice), indicating them functionally to be of T-helper variety. Unlike MHS, lipid A administration i.p. resulted in MHS like response in C3H/HeN but not in C3H/HeJ mice. MHS action has been traced to an induction of IL1 release by macrophages of MHS treated animals by chromatographic analysis of macrophage derived supernatants. IL1, in turn, according to the prevalent concepts would stimulate immature T cells to become mature IL2 producer cells, allowing T helper cell proliferation through IL2 release.

A comparative study of the intravesical MTP and BCG treatment of transplantable bladder cancer

We induced transitional cell cancer of the urinary bladder in Fischer rats by feeding them N-[4(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT). Tumors were subsequently transplanted orthotopically in the bladder submucosa of Fischer rats. This animal model was used to compare the therapeutic effects of maltose tetrapalmitate (MTP), and bacillus Calmette Guérin (BCG). The routes of administration compared were intravesical alone or intravesical and oral for MTP, and intravesical alone or intravesical and subcutaneous for BCG. The intravesical and oral MTP treatment was more effective than the intravesical and subcutaneous BCG as regards the tumor size, incidence of tumor metastasis and the immunologic status of the tumor bearing host.