Several conjugates of model allergen ovalbumin (OA) and the copolymer of N-vinyl pyrrolidone and maleic anhydride (VMA) modified with epsilon-aminocaproic acid (Acp) were prepared in different OA/Acp-VMA ratios. All conjugates were separated by ultrafiltration and analyzed by HPLC. Their compositions were determined by amino acid analysis and UV spectrometry. To detect immunogenicity, all conjugates were injected intraperitoneally into (CBAxC57BL/6)F1 mice three times in 3-week intervals in OA doses equivalent to 0.5, 10, and 100 micrograms/mouse. Only the conjugate containing 20%OA (OA(20%)-Acp-VMA) did not induce significant quantities of anti-OA IgE, but did induce anti-OA IgG antibodies in dose-dependent manner comparable to that of unmodified OA. Mixtures of OA and Acp-VMA or OA modified only with VMA without Acp activation with Acp induced dose-dependent anti-OA IgE and IgG antibody formation comparable to that of OA. Using passive cutaneous anaphylaxis, RAST inhibition and leukocyte histamine release, a significant reduction of allergenicity was noted using OA(20%)-Acp-VMA. This conjugate stimulated activation of the OA-specific T-cell hybrid 3DO-548 comparable to that of unconjugated OA. During experimental allergen-specific hyposensitization with OA(20%)-Acp-VMA, suppression of anti-OA IgE response and elevation of anti-OA IgG responses were noted when compared with unmodified OA. Selective blockade of B-cell epitopes of allergen may occur using the carrier Acp-VMA to reduce allergenicity while not affecting T-cell epitopes, thereby preserving immunogenicity. This approach of chemical modification of allergen suggests new opportunities in the creation of preparations for allergen-specific immunotherapy.

Allergens↗

PubMedDate not supplied

The role of mast cells and basophils in immunoregulation.

The production of a wide range of cytokines by mast cells in response to activation by allergen places the mast cell in the center of the allergic inflammatory response. These cytokines may lead to eosinophil, basophil, and T cell recruitment. Coordinated production of IL-4 and IL-5 by TH2 helper cells enhanced IgE responsivity, thus perpetuating the allergic inflammatory response. As a variety of leukocytes involved in the allergic inflammatory response may produce cytokines, the critical nature of these mediators of inflammation in promoting and perpetuating inflammation is now well appreciated.

Basophils↗

PubMedDate not supplied

In vivo and in vitro immunomodulation induced by the extract of the mycelium fungus Polyporus squamosus.

The mycelial mass of the fungus Polyporus Squamosus strain 64 (PS-64) was disintegrated by mechanical and ultrasound treatments. After centrifugation, the supernatant containing the disintegrate was dialyzed and lyophilized. The resultant PS-64 extract was subsequently investigated as an immunomodulator of IgE and IgG responses to ovalbumin (OA) in (CBAxC57BL/6)F1 mice using passive cutaneous anaphylaxis (PCA) and enzyme-linked immunosorbent assay (ELISA), respectively. Multiple injections of PS-64 extract in doses of 1.5, 15, and 150 mg/kg administered before the primary or secondary immunization of mice with OA resulted in a dose-dependent inhibition of both IgE and IgG antibody responses to OA. In contrast to the inhibition of the anti-OA IgE response noted during the entire 3-week observation period, the anti-OA IgG response was restored to control level by the third week of secondary immunization. The glass microfiber-based whole blood histamine release assay demonstrated that various concentrations of the PS-64 extract did not influence histamine release induced either by anti-IgE or by specific allergens from basophils derived from whole blood of allergen-sensitized patients. Using the hemolytic plaque assay, significant suppression of IgM-secreting cell formation was noted in (CBAxC57BL/6)F1 mice administered various doses of the PS-64 extract before immunization. The PS-64 extract inhibited the in vitro proliferation of human mononuclear cells upon stimulation with phytohemagglutinin (PHA). In a dose-dependent manner, the PS-64 extract also inhibited delayed-type hypersensitivity reaction and skin graft rejection, similar to the effect noted with usage of Cyclosporin A (CsA) in (CBAxC57BL/6)F1 mice. Our investigation suggests that the immunomodulatory effects of PS-64 should be studied further for potential clinical therapeutic utility.

Adjuvants, Immunologic↗