Immune responses to nematode exoantigens: sensitizing antibodies and basophil histamine release

Abstract

High levels of IgE and eosinophilia are found in both allergy and helminth infections, but allergic symptoms are rare in naturally acquired helminth infections. The interrelation of specific IgE antibodies and in vitro basophil histamine release (HR) induced by exoantigens from the larval stages (L2/L3) of the nematodes Toxocara canis and Ascaris suum was examined in 148 patients visiting an outpatient clinic for parasitic diseases. The antigen sensitivity of the basophils was found to be dependent not only on the absolute amount of antigen-specific IgE present in patient plasma, but also on the ratio between specific and total IgE. Thus, large HR was observed in some patients in response to helminth antigens despite low levels of both specific and total IgE content in plasma. Patients with eosinophilia showed greater IgE-mediated HR than the other patients examined. In contrast, only five patients showed HR after challenge with anti-IgG4, despite the presence of high levels of antigen-specific IgG4 and IgG1 in all patients showing specific IgE antibodies.

Lack of Basophilia in Human Parasitic Infections

“…22 Basophils from Toxocara-, Ascaris-, Onchocerca-, Wuchereria-, Strongyloides-, and Schistosoma-infected patients have been shown to release histamine in response to parasite antigen. [23][24][25][26][27] The amount of histamine released by basophils in response to Toxocara antigen was found to be proportional to the serum concentration of Toxocara antigen-specific IgE. 23 In addition to high levels of IgE, human helminth infections are also associated with increased production of interleukin (IL)-4, the prototypical Th2 cytokine.…”

“…[23][24][25][26][27] The amount of histamine released by basophils in response to Toxocara antigen was found to be proportional to the serum concentration of Toxocara antigen-specific IgE. 23 In addition to high levels of IgE, human helminth infections are also associated with increased production of interleukin (IL)-4, the prototypical Th2 cytokine. Basophils from filaria-infected patients have been shown to release IL-4 in response to L3 larvae and filarial antigen, 28 and basophils from uninfected individuals have been shown to release IL-4 after stimulation with Schistosoma egg antigen.…”

Melatonin modulates allergic lung inflammation

“…It is well known that melatonin can influence some aspects of the immune response such as antibody production [Kuribayashi et al, 1981;Caroleo et al, 1992], including the production of IgG1 isotype in response to an OA challenge, which increased in the presence of melatonin [Shaji et al, 1998]. IgG1 antibodies are of particular interest, as they can bind to mast cell receptors and mediate cell degranulation [Nielsen et al, 1994;Miyajima et al, 1997]. Considering the effect of melatonin upon immunoglobulin production, we evaluated whether the reduced production of immunoglobulins in sensitized, pinealectomized rats were involved in the reduction of cell migration through a decrease of mast cell degranulation.…”

Regulation of secretion of IL-4 and IgG1 isotype by melatonin-stimulated ovalbumin-specific T cells

“…It may be concluded from these experiments that melatonin also augments the ability of Th cells to help B cells, as evidenced by augmentation of the levels of IgG1 secretion. Preferential production of IgG1 antibodies is of particular interest, since this isotype binds to mast cell receptors and can mediate mast cell degranulation that may confer increased resistance to nematode parasites and may contribute to its ability to induce anaphylaxis [25,26].…”