We have previously reported that splenic non-B non-T (NBNT) cells produce IL-4 in response to FcR cross-linkage.8, 9 Following infection by N. brasiliensis or treatment with goat anti-IgD antibody, both of which induce a strong Th2/IgE response, there are increased numbers of splenic NBNT cells and enhanced IL-4 producing capacity by these cells.10 Subsequently, these IL-4-producing splenic NBNT cells were identified as basophils by electron microscopic analysis.11 Coculture or in vivo treatment with IL-3 enhanced IL-4 production by basophils in response to FcR cross-linkage.9 It was further shown that IL-3 primarily produced by activated CD4 T cells induced production of IL-4 by splenic NBNT cells during Schistosoma mansoni infection,12 presumably amplifying the vigorous Th2 type immune response that occurs in the course of this infection. Treatment with IL-3 resulted in enhanced IL-4 production by splenic T cells from mice that had been infected with Trichinella spiralis,13 implying that IL-3-mediated basophil activation might be an important mechanism through which Th2 dominance is established in immune responses to helminths. Indeed, we have recently reported that IL-4 producing cells accumulated in the liver in the course of N. brasiliensis infection.4 Electron microscopic analysis has confirmed their identity as basophils, supporting earlier observations on cells classified as splenic NBNT cells. The accumulation of basophils during N. brasiliensis infection is also associated with the enhanced IL-4 production by basophils (on a per cell basis). An important issue that requires resolution is the nature of the stimuli that result in basophil IL-4 production during N. brasiliensis infection.
Basophils express high levels of FcεRI and cross-linkage of FcεRI or of FcγRII/RIII induces both mediator release from, and IL-4 production by, basophils. The probable importance of antigen-antibody complex-mediated basophil activation is further implied by the strong association of immune responses in which basophil activation occurs with the development of robust IgE responses. The molecular mechanisms underlying IgE/FcεRI mediated activation have been extensively studied in mast cells. Cross-linkage of FcεRI leads to the activation of multiple signaling molecules, including PLCγ, PI3K, MAPK, and PKC, all of which regulate cytokine/chemokine production and mediator release.14, 15 Whether the pathway that operates within the basophils is different from that of mast cells needs further investigation. Addition of IL-3 enhances production of IL-4 and mediator release by basophils, suggesting synergy between the FcεRI-mediated pathway and the IL-3 mediated pathway.9 However, in certain circumstances, basophil activation occurs in the absence of immunoglobulins, such as in mice that lack B cells and antibodies, indicating that immunoglobulin-independent activation of basophils is also operative in vivo.
IL-3 and GM-CSF play essential roles in the differentiation and survival of several myeloid lineages, including basophils, eosinophils, and mast cells. Culture of bone marrow cells with IL-3 promotes the differentiation of bone marrow progenitors into basophils as well as mast cells.16 Paradoxically, the development of basophils is not impaired in mice deficient in IL-3, although the enhanced production of basophils that occurs upon parasitic infection appeared to be compromised in the absence of IL-3.17 IL-3 is well known for its capacity to prime basophils for increased production of cytokines and mediators in response to both immune complex-dependent and immune complex-independent activation. IL-3 synergizes with IL-18 in immune complex-independent induction IL-4 production from bone marrow-derived basophils.16 IL-3 also enhanced immune complex-independent mediator release from basophils stimulated with C5a.18 The underlying molecular mechanism of IL-3-mediated basophil priming is not well understood. Recent studies have shown that IL-3 enhances MEK/ERK activation in anti-IgE stimulated basophils.14 IL-3 treatment also induces the activation of JAK2, STAT5 and PLA2 in these cells.15
In addition to modulating signaling activities that lead to cytokine production, IL-3 also enhances transendothelial migration of basophils.19
CD4 T CELLS
CD4 T cells play a major role in basophil responses in helminthic infections. Infection of immunodeficient Rag2-/- mice with N. brasiliensis fails to result in enhanced numbers of basophils or in their enhanced capacity to produce IL-4.4 Transfer of CD4 T cells into Rag2-/- recipients at the time of infection restored both accumulation of basophils and the increase in their capacity to secrete IL-4 upon stimulation. Furthermore, the transferred T cells need to be capable of mounting an immune response; CD4 T cells from mice transgenic for TCRα and β chains coding for a receptor for a cytochrome C peptide failed to equip Rag2-/- recipients with the capacity to develop helminth-stimulated basophil activation and IL-4 production.4 This process does not depend on IL-4 production by the CD4 T cells, since CD4 T cells from IL-4-/- donors are fully effective in restoring basophil accumulation and secretion of IL-4 by basophils.4 As previously reported, IL-3 derived from activated T cells may be the important factor for the IL-4 production from splenic NBNT cells during Schistosoma mansoni infection.12 These results suggest that antigen-mediated activation of CD4 T cells during helminthic infection leads to the production of the IL-3 that might be necessary for the basophil activation. Nevertheless, in vivo neutralization of IL-3 in the course of N. brasiliensis infection only partially inhibited the accumulation of basophils in the liver and their subsequent IL-4 production.4 Among other cytokines that need study in vivo are IL-18, which, through its synergy with IL-3, could allow low concentrations for IL-3 to be effective. In addition, IL-9 is known to have important effects in mast cell development and should be studied as a possible T cell derived factor important in basophil responses.20
Interestingly, it does appear that Th2 type immunity is needed for the CD4 T cell effect. Infection with Toxoplasma gondii, which induces a potent Th1 response, fails to lead to accumulation of basophils or enhanced IL-4-production by these cells.4 In general, Th1 cells do produce IL-3, although in most cases less that produced by Th2 cells. Further efforts should be made to identify T cell derived factors critical for the basophil activation.
OTHER INNATE TYPE STIMULI
Basophils obtained from peripheral blood express TLR2 and TLR4, as determined both by PCR and flow cytometry.21 Human basophils secrete IL-4 and IL-13 in response to peptidoglycan, a TLR2 ligand but not to LPS, a TLR4 ligand.21, 22 Similarly, TLR ligands enhance the production of cytokines and mediators when basophils are stimulated through IgE-dependent or independent pathway.22 Basophils were also shown to produce IL-4 following stimulation with Schistosoma egg antigens.23 Antigens derived from Helicobacter pylori and urokinase were shown to activate basophils through N-formyl-peptide receptor-like (FPRL) 1 & 2 and induce chemotaxis of basophils.24, 25 The HIV glycoprotein gp120 binds to H chain of surface IgE, resulting in induction of cytokine production from basophils.26 Complement 5a (C5a) is another IgE-independent stimulus capable of activating human basophils to produce cytokines and mediators.27, 28 Taken together, basophils may well be activated by parasitic, bacterial or viral-associated products through activation of innate type machinery.
ACTIVATION MECHANISM OF BASOPHILS DURING N. BRASILIENSIS INFECTION
Which of these mechanisms are responsible for basophil activation during N. brasiliensis infection? Apparently, CD4 T cells play an important role in activating basophils in part via production of IL-3 as neutralization of IL-3 partially diminished both accumulation and IL-4 production by basophils.4 While basophil responses seem to be restricted to Th2 type immunity, IL-3 is produced by most activated T cells. Therefore, production of IL-3 by itself is inadequate for basophil activation or inhibitors are induced during Th1 responses. It is possible that "innate-type" signals derived from N. brasililensis are needed to induce basophil activation. However, whether they operate through TLRs or other receptors described above needs to be determined. It was previously demonstrated that an extract of N. brasiliensis stimulates IgE and IgG1 production by inducing de novo isotype switching and the production of IL-4/IL-13.29 Moreover, injection of N. brasiliensis extract together with protein antigens was shown to act as adjuvant and to induce development of antigen specific Th2 immune response.30-32 Although it is not well understood how such immune differentiation by N. brasiliensis extract is achieved, it is possible that the activation of TLRs or other innate type receptors expressed on the basophils might be involved in this process.
Takeda K, Kaisho T, Akira S. Toll-like receptors. Annu. Rev. Immunol. 2003; 21: 335-376.
Schnare M, Barton GM, Holt AC et al. Toll-like receptors control activation of adaptive immune responses. Nature Immunology 2001; 2: 947-950.
Sabroe I, Parker LC, Wilson AG, Whyte MK, Dower SK. Toll-like receptors: their role in allergy and non-allergic inflammatory disease. Clin. Exp. Allergy 2002; 32: 984-989.
Min B, Prout M, Hu-Li J et al. Basophils produce IL-4 and accumulate in tissues after infection with a Th2-inducing parasite. J. Exp. Med. 2004; 200: 507-517.
Brown SJ, Galli SJ, Gleich GJ, Askenase PW. Ablation of immunity to Amblyomma americanum by anti-basophil serum: cooperation between basophils and eosinophils in expression of immunity to ectoparasites (ticks) in guinea pigs. J. Immunol. 1982; 129: 790-796.
Mukai K, Matsuoka K, Taya C et al. Basophils play a critical role in the development of IgE-mediated chronic allergic inflammation independently of T cells and mast cells. Immunity 2005; 23: 191-202.
Luccioli S, Brody DT, Hasan S et al. IgE (+), Kit (-), I-A/I-E (-) myeloid cells are the initial source of Il-4 after antigen challenge in a mouse model of allergic pulmonary inflammation. J. Allergy Clin. Immunol. 2002; 110: 117-124.
Ben-Sasson SZ, Le Gros G, Conrad DH, Finkelman FD, Paul WE. Cross-linking Fc receptors stimulate splenic non-B, non-T cells to secrete interleukin 4 and other lymphokines. Proc. Natl. Acad. Sci. U.S.A. 1990; 87: 1421-1425.
Le Gros G, Ben-Sasson SZ, Conrad DH et al. IL-3 promotes production of IL-4 by splenic non-B, non-T cells in response to Fc receptor cross-linkage. J. Immunol. 1990; 145: 2500-2506.
Conrad DH, Ben-Sasson SZ, Le Gros G, Finkelman FD, Paul WE. Infection with Nippostrongylus brasiliensis or injection of anti-IgD antibodies markedly enhances Fc-receptor-mediated interleukin 4 production by non-B, non-T cells. J. Exp. Med. 1990; 171: 1497-1508.
Seder RA, Paul WE, Dvorak AM et al. Mouse splenic and bone marrow cell populations that express high-affinity Fc epsilon receptors and produce interleukin 4 are highly enriched in basophils. Proc. Natl. Acad. Sci. U.S.A. 1991; 88: 2835-2839.
Kullberg MC, Berzofsky JA, Jankovic DL et al. T cell-derived IL-3 induces the production of IL-4 by non-B, non-T cells to amplify the Th2-cytokine response to a non-parasite antigen in Schistosoma mansoni-infected mice. J. Immunol. 1996; 156: 1482-1489.
Korenaga M, Akimaru Y, Hashiguchi Y. Exogenous interleukin-3 enhances IL-4 production by splenic CD4+ cells during the early stages of a Trichinella spiralis infection. Int. Arch. Allergy Immunol. 1998; 117: 131-137.
Vilarino N, Miura K, MacGlashan DW Jr. Acute IL-3 priming up-regulates the stimulus-induced Raf-1-Mek-Erk cascade independently of IL-3-induced activation of Erk. J. Immunol. 2005; 175: 3006-3014.
Galli SJ, Kalesnikoff J, Grimbaldeston MA et al. Mast cells as "tunable" effector and immunoregulatory cells: recent advances. Annu. Rev. Immunol. 2005; 23: 749-786.
Yoshimoto T, Tsutsui H, Tominaga K et al. IL-18, although antiallergic when administered with IL-12, stimulates IL-4 and histamine release by basophils. Proc. Natl. Acad. Sci. U.S.A. 1999; 96: 13962-13966.
Lantz CS, Boesiger J, Song CH et al. Role for interleukin-3 in mast-cell and basophil development and in immunity to parasites. Nature 1998; 392: 90-93.
Eglite S, Pluss K, Dahinden CA. Requirements for C5a receptor-mediated IL-4 and IL-13 production and leukotriene C4 generation in human basophils. J. Immunol. 2000; 165: 2183-2189.
Iikura M, Ebisawa M, Yamaguchi M et al. Transendothelial migration of human basophils. J. Immunol. 2004; 173: 5189-5195.
Ochi H, Hirani WM, Yuan Q et al. T helper cell type 2 cytokine-mediated comitogenic responses and CCR3 expression during differentiation of human mast cells in vitro. J. Exp. Med. 1999; 190: 267-280.
Sabroe I, Jones EC, Usher LR, Whyte MK, Dower SK. Toll-like receptor (TLR) 2 and TLR4 in human peripheral blood granulocytes: a critical role for monocytes in leukocyte lipopolysaccharide responses. J. Immunol. 2002; 168: 4701-4710.
Bieneman AP, Chichester KL, Chen YH, Schroeder JT. Toll-like receptor 2 ligands activate human basophils for both IgE-dependent and IgE-independent secretion. J. Allergy Clin. Immunol. 2005; 115: 295-301.
Falcone FH, Dahinden CA, Gibbs BF et al. Human basophils release interleukin-4 after stimulation with Schistosoma mansoni egg antigen. Eur. J. Immunol. 1996; 26: 1147-1155.
de Paulis A, Montuori N, Prevete N et al. Urokinase induces basophil chemotaxis through a urokinase receptor epitope that is an endogenous ligand for formyl peptide receptor-like 1 and-like 2. J. Immunol. 2004; 173: 5739-5748.
de Paulis A, Prevete N, Fiorentino I et al. Basophils infiltrate human gastric mucosa at sites of Helicobacter pylori infection, and exhibit chemotaxis in response to H. pylori-derived peptide Hp (2-20). J. Immunol. 2004; 172: 7734-7743.
de Paulis A, Florio G, Prevete N et al. HIV-1 envelope gp41 peptides promote migration of human Fc epsilon RI+ cells and inhibit IL-13 synthesis through interaction with formyl peptide receptors. J. Immunol. 2002; 169: 4559-4567.
Ochensberger B, Daepp GC, Rihs S, Dahinden CA. Human blood basophils produce interleukin-13 in response to IgE-receptor-dependent and -independent activation. Blood 1996; 88: 3028-3037.
Ochensberger B, Rihs S, Brunner T, Dahinden CA. IgE-independent interleukin-4 expression and induction of a late phase of leukotriene C4 formation in human blood basophils. Blood 1995; 86: 4039-4049.
Ehigiator HN, Stadnyk AW, Lee TD. Extract of Nippostrongylus brasiliensis stimulates polyclonal type-2 immunoglobulin response by inducing De novo class switch. Infect. Immun. 2000; 68: 4913-4922.
Liu Z, Liu Q, Hamed H et al. IL-2 and autocrine IL-4 drive the in vivo development of antigen-specific Th2 T cells elicited by nematode parasites. J. Immunol. 2005; 174: 2242-2249.
Holland MJ, Harcus YM, Riches PL, Maizels RM. Proteins secreted by the parasitic nematode Nippostrongylus brasiliensis act as adjuvants for Th2 responses. Eur. J. Immunol. 2000; 30: 1977-1987.
Marsland BJ, Camberis M, Le Gros G. Secretory products from infective forms of Nippostrongylus brasiliensis induce a rapid allergic airway inflammatory response. Immunol. Cell Biol. 2005; 83: 40-47.
Marone G, Triggiani M, de Paulis A. Mast cells and basophils: friends as well as foes in bronchial asthma? Trends in Immunology 2005; 26: 25-31.
Voehringer D, Shinkai K, Locksley RM. Type 2 immunity reflects orchestrated recruitment of cells committed to IL-4 production. Immunity 2004; 20: 267-277.
Dambach DM, Watson LM, Gray KR, Durham SK, Laskin DL. Role of CCR2 in macrophage migration into the liver during acetaminophen-induced hepatotoxicity in the mouse. Hepatology 2002; 35: 1093-1103.
Rose CE Jr, Sung SS, Fu SM. Significant involvement of CCL2 (MCP-1) in inflammatory disorders of the lung. Microcirculation 2003; 10: 273-288.
Gu L, Tseng S, Horner RM et al. Control of TH2 polarization by the chemokine monocyte chemoattractant protein-1. Nature 2000; 404: 407-411.
Bischoff SC, Krieger M, Brunner T, Dahinden CA. Monocyte chemotactic protein 1 is a potent activator of human basophils. J. Exp. Med. 1992; 175: 1271-1275.
Devouassoux G, Metcalfe DD, Prussin C. Eotaxin potentiates antigen-dependent basophil IL-4 production. J. Immunol. 1999; 163: 2877-2882.
Gessner A, Mohrs K, Mohrs M. Mast cells, basophils, and eosinophils acquire constitutive IL-4 and IL-13 transcripts during lineage differentiation that are sufficient for rapid cytokine production. J. Immunol. 2005; 174: 1063-1072.
Gibbs BF, Haas H, Falcone FH et al. Purified human peripheral blood basophils release interleukin-13 and preformed interleukin-4 following immunological activation. Eur. J. Immunol. 1996; 26: 2493-2498.
Gibbs BF. Human basophils as effectors and immunomodulators of allergic inflammation and innate immunity. Clin. Exp. Med. 2005; 5: 43-49.
Mitre E, Taylor RT, Kubofcik J, Nutman TB. Parasite antigen-driven basophils are a major source of IL-4 in human filarial infections. J. Immunol. 2004; 172: 2439-2445.
Khodoun MV, Orekhova T, Potter C, Morris S, Finkelman FD. Basophils initiate IL-4 production during a memory T-dependent response. J. Exp. Med. 2004; 200: 857-870.
Aoki I, Kinzer C, Shirai A, Paul WE, Klinman DM. IgE receptor-positive non-B/non-T cells dominate the production of interleukin 4 and interleukin 6 in immunized mice. Proc. Natl. Acad. Sci. U.S.A. 1995; 92: 2534-2538.
Gauchat JF, Henchoz S, Mazzei G et al. Induction of human IgE synthesis in B cells by mast cells and basophils. Nature 1993; 365: 340-343.
Yanagihara Y, Kajiwara K, Basaki Y et al. Cultured basophils but not cultured mast cells induce human IgE synthesis in B cells after immunologic stimulation. Clin. Exp. Immunol. 1998; 111: 136-143.
Hida S, Tadachi M, Saito T, Taki S. Negative control of basophil expansion by IRF-2 critical for the regulation of Th1/Th2 balance. Blood 2005; 106: 2011-2017.
Kane CM, Cervi L, Sun J et al. Helminth antigens modulate TLR-initiated dendritic cell activation. J. Immunol. 2004; 173: 7454-7461.