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Possible role of FcR+ T cells in the regulation of the IgE response
B E G U L A T O R Y FeR
401
POSSIBLE ROLE OF FcR + T CELLS IN T H E REGULATION OF THE IgE RESPONSE by K. I s h i z a k a
Subdeparlmenl of Immunology, The Johns Hopkins Universilg School o[ Medicine at the Good Samaril~tn Hospital, Ballimore, MD 21239 (USA) One of the problems remaining to be solved in the antibody responses is dissociation among antibody responses of different isotypes. The dissociation is frequently observed between the IgE-antibody response and the IgG-antibody response, and suggests the existence of isotypespecific regulatory mechanisms. Our interests in the Fcl% particularly Fcr are based on a speculation that the receptors, or soluble factors related to the receptors, i. e. fgE-binding (Ig-BF) factors, may be involved in the isotypc-specific regulation. 1) Role o/ 1,qE-BF in the regulation of
the lgE response. Our studies on the isotype-specitic regulation of the IgE response were initiated using the infection of rats with NippostronggIus brasiliensis (Nb) as all experimental model. This study led to the detection of two ]'-cell factors which have affinity for lgE and selectively regulate the IgE response [1]. One of them selectively enhances the IgE response, while another ]gE-BF suppresses the response. The two factors have comparable molecular weights, i. e. 13,000 to 15,000 daltons, and appear to be derived from the same subset of T cells. Both factors share a common antigenic determinant with Fc~l~ on both B and T cells [2]. Subsequent studies have shown that not only Nb infection but also an.injection of Bordelella pertussis vaccine induced the formation of 15-Kd IgE-potentiating factor (IgE-PF). Spleen cells of rats primed with alum-absorbed anti-
gen formed IgE-PF upon antigenic stimulation [3]. In contrast, repeated injections of complete Freund's adjuvant (CFA), which suppress the IgE antibody response to an unrelated antigen, induce the formation of IgE-suppressive factor (IgE-SF) [4]. Spleen cells of rats primed with an antigen included in CFA produced IgE-SF upon antigenic stimulation [3]. The selective formation of either I g E - P F or IgE-SF by FcR + T cells m a y explain genetic differences in the IgE response. When mice were immunized with alum-absorbed ovalbumin (OA), splenic T cells of a high IgE responder, BGD2F1 mice, formed l g E - P F upon antigenic stimulation, while those of a low lgE responder, SJI. mice, formed IgE-SF [5]. It is known that irradiation with low dose X-ray or cyclophosphamide treatment prior to immunization enhances the IgE response. Indeed, recent experiments show that X-irradiation or eyclophosphamide treatment of SJL mice switch their T cells to form IgE-PF. A correlation between the enhancement of the IgE response and the formation of IgE-PF, and that between suppression of IgE response and formation of IgE-SF strongly suggest that IgE-binding factors (IgEBF) are involved in tile lgE response
in vivo. 2) Significance of oli.qosaccharides in
lhe I.qE-BF in their biologic activities. Major differences between the I g E - P F and IgE-SF are their carbohydrate moieties. IgE-PF has both
402
7e F O R U M D'IMMUNOLOGIE
sialidated N-linked oligosaccharide and O-linked oligosaccharide, while IgE-SF contains only O-linked oligosaccharide with galactose ~ N-acetylgalactosamine as terminal sugars [6]. Therefore, I g E - P F has affinity for lentil lectin and ConA, while IgE-SF has affinity for peanut agglutinin (PNA). We hypothesized that these oligosaccharides play an important role in the biologic activities of IgE-BF, because inhibition of assembly of N-linked oligosaceharides switches the same cells from the formation of IgE-PF to the formation of IgE-SF [6]. In addition to the 15-Kd I g E - B F described above, FOR.- T cells also produce the 60-Kd and 30-Kd lgE-BF. Some of these factors have either potentiating activity or suppressive activity; however, a correlation between the biologic activities and affinity for lectin does not apply for the 60-Kd and 30-Kd IgE-BF. The 30-Kd IgE-BF having affinity for PNA frequently lacked biologic activities [2, 4]. IgE suppressor factor (IgE-TsF) described by Suemura el al. [7] has a molecular weight of 6 0 K d or higher, and has affinity for IgE; however, this factor has affinity for lentil lectin. As will be described, the 60-Kd IgE-BF has multiple sites for N-linked oligosaccharides and O-linked oligosaccharides. Binding of IgE-TsF to lentil lectin appears to be due to the presence of a N-linked oligosaccharide, which is not included in the 15-Kd IgE-BF. Evidence has accumulated which suggests that the same FoR + T cells can produce both the 15-Kd IgE-PF and IgE-SF [8]. We predicted that the two factors share common precursor molecules. This hypothesis is supported by gene cloning of rodent IgE-BF. Using mBNA of a ratmouse T hybridoma, 23B6, which produces IgE-SF upon incubation with IgE, Martens el al. [9] succeeded in obtaining eDNA clones encoding rodent IgE-BF. Transfection of COS-7 monkey kidney cells with a eDNA clone, 8.3, resulted in the formation of the 60-Kd and l l - K d IgE-BF. The nucleotide sequence of the eDNA evoked the amino acid sequence of the
60-Kd IgE-BF. The factor represents a single polypeptide consisting of 556 amino acids with two potential sites for N-linked glycosylation and several potential sites for post-translational proteolytic cleavage. We speculate t h a t the l l-Kd IgE-BF from the transfected COS-7 cells is a cleavage product of the 60-Kd precursor molecule. An interesting finding was that both the 60-Kd and l l - K d IgE-BF from the eDNA clone had atlinity for lentil leetin, and both factors selectively potentiated the IgE response. It should be noted that hybridoma cells 23B6, from which mRNA was obtained for the construction of eDNA libraries, produced IgE-SF. The findings support the view that IgE-PF and IgE-SF may be encoded by the same mRNA, and biologic activities of the factors are decided b y post-translational glycosylation process. 3) FcR+ I' cells are mulli-/unclional regulalorg cells.
The cell source of IgE-BF is T cells with either Fcd~ or Fc-(R or both [8]. These cells respond to homologous IgE or interferon-like substances which are released from antigen-primed T cells. Even when FccR are not detectable, we imagine that the cells bear a small number of Fcr which may not be detectable by rosetting technique. This speculation is based on the fact that some Fc~lR § 1 6 2 ) cells respond to antibodies against IgE-BF, which cross-reacts with F e a r but not with Fc,fll, to form IgE-BF [2]. However, none of the interferon-like substance, IgE or anti-IgE-BF, determines the nature of IgE-BF formed. Under physiological conditions, the N-glycosylation of IgE-BF is controlled by two T-cell factors which either enhance or inhibit the N-glycosylation. The glycosylation-enhancing factor (GEF) is derived from Lyt-l+ T cells, and is a kallikrein-like enzyme with lectinlike properties [10]. Glycosylationinhibiting factor (GIF) is a fragment of phosphorylated lipomodulin, a phospholipase inhibitory protein [11]. It was found that unprimed FoR + T cells
R E G U L A T O R Y FcR from Lewis rats or BALB/c mice formed IgE-PF when they were incubated with IgE (or interferon) in the presence of GEF, but the same cells produced IgE-SF in the presence of G1F. In these systems, the source of I g E - P F / I g E - S F is not antigen-primed. Recently, however, we obtained an antigen-specific FcR + T-cell clone and antigen-specific T hybridomas which formed IgE suppressive factor upon incubation with antigen-pulsed macrophages. From the classical concept in cellular immunology, these cells may be called ~ IgE-specific suppressor T cells )). However, if one incubates the hybridomas with antigen-pulsed maerophages in the presence of GEF, the same cells produce IgE-PF. Since these cells bear FcyB, it is quite possible that they may form IgG-BF [12]. We hypothesize that F e b +, antigen-specific T cells are multifunctional, and could either suppress or enhance the IgE and IgG antibody responses depending on the environment of the cells.
]t~('/erC,qcSS. [1] 1SItlZAKA, X.,
SUEMU1RA, M,,
YODOI, J. & HIRASHIM~, M., Fed. Proe., 1981, 40, 2162.
403
[2] HUFF, T. F., YODOl, J., U~DE, T. & ISHIZAKA, [~., ,1. Immunol., 1984, 132, 406. [3] UEDE, T., HUFF, T. F. & ISHIZAKA, K., J. lmmunol., 1982, 129, 1384. [4] HIRASHIMA, M., YODOI, J. & ISHiZAK.% K., J. Immunol., 1980, 125, 2514. [5] UEDE, T. & ISHIZAKA, I(., J. Immunol., 1984, 133, 359. [61 YODOI, J., t~III~IASH 13IA, ~[. & ISmZt~KA, K., d. immunol., 1982, 128, 289. [7] SUEMURA, M., SHIIIO, O., DEGUcni, H., YAMAMUllA, Y., BSTTCHER, I. ~5 t(ISIIIMOTO, T., J. Immunol., 1981, 127, 465. [8] ISHIZAKA, K., Anll. Reo. Immunol., 1984, 2, 159. [9] M.~BTENS, C. L., HUFF, T. F., JARDIEU, P., TROUSTINE, M. L., COFFMAN, 1~. L., ISmZAKA, K. & MOORE, K. \u Proc. nat. Acad. Sci. (Wash.), 1985 (in press). [10l IWATA, M., MUNOZ, J. J. & IStlIZAKA, K., J. Immunol., 1983, 131, 1954. [11] U z o r , T., HmATA, F., HII/ASHIMA, M. & ]SHIZAKA, 1~., ,J. Immunol., 1983, 130, 878. [12] FRID3IA-N, W. H., RABOU/-~DINCOMBE, NEAUPORT-SAUTES, C. & GmLER, H., lmmunol. Rev.. 1981, 56, 51.
REGULATORY MECHANISM OF IgA AND lgE PRODUCTION by M. Adachi, N. Noro, T. Nagai and J. Yodoi I~slilule for Imrmmologg, Facullg o[ Medicine, Kyolo Universily, Kyoto, 606 (Japan) Inlroduclion. Accumulating evidence shows that T cells bearing class-specific Fc receptors (FOR) play an important role in isotypic regulation via releasing soluble factors [1, 2, 3]. These factors include IgG-binding factors (IgG-BF) reported by Fridman and his colleagues [21 and IgE-binding factors (IgE-BF) by lshizaka el al. [3, 4, 5]. IgG-BF and IgE-BF regulate IgG
and IgE responses, respectively, in vilro in a class-specific manner. Furthermore, both of the BF are produced by T cells bearing F e b of corresponding isotypes. Abnormal regulation of IgA production, which is important in immune responses in secreting organs, is observed in human diseases such as selective IgA deficiency and IgA nephropathy. In order to determine tile pathophysiological mechanism of these
401
POSSIBLE ROLE OF FcR + T CELLS IN T H E REGULATION OF THE IgE RESPONSE by K. I s h i z a k a
Subdeparlmenl of Immunology, The Johns Hopkins Universilg School o[ Medicine at the Good Samaril~tn Hospital, Ballimore, MD 21239 (USA) One of the problems remaining to be solved in the antibody responses is dissociation among antibody responses of different isotypes. The dissociation is frequently observed between the IgE-antibody response and the IgG-antibody response, and suggests the existence of isotypespecific regulatory mechanisms. Our interests in the Fcl% particularly Fcr are based on a speculation that the receptors, or soluble factors related to the receptors, i. e. fgE-binding (Ig-BF) factors, may be involved in the isotypc-specific regulation. 1) Role o/ 1,qE-BF in the regulation of
the lgE response. Our studies on the isotype-specitic regulation of the IgE response were initiated using the infection of rats with NippostronggIus brasiliensis (Nb) as all experimental model. This study led to the detection of two ]'-cell factors which have affinity for lgE and selectively regulate the IgE response [1]. One of them selectively enhances the IgE response, while another ]gE-BF suppresses the response. The two factors have comparable molecular weights, i. e. 13,000 to 15,000 daltons, and appear to be derived from the same subset of T cells. Both factors share a common antigenic determinant with Fc~l~ on both B and T cells [2]. Subsequent studies have shown that not only Nb infection but also an.injection of Bordelella pertussis vaccine induced the formation of 15-Kd IgE-potentiating factor (IgE-PF). Spleen cells of rats primed with alum-absorbed anti-
gen formed IgE-PF upon antigenic stimulation [3]. In contrast, repeated injections of complete Freund's adjuvant (CFA), which suppress the IgE antibody response to an unrelated antigen, induce the formation of IgE-suppressive factor (IgE-SF) [4]. Spleen cells of rats primed with an antigen included in CFA produced IgE-SF upon antigenic stimulation [3]. The selective formation of either I g E - P F or IgE-SF by FcR + T cells m a y explain genetic differences in the IgE response. When mice were immunized with alum-absorbed ovalbumin (OA), splenic T cells of a high IgE responder, BGD2F1 mice, formed l g E - P F upon antigenic stimulation, while those of a low lgE responder, SJI. mice, formed IgE-SF [5]. It is known that irradiation with low dose X-ray or cyclophosphamide treatment prior to immunization enhances the IgE response. Indeed, recent experiments show that X-irradiation or eyclophosphamide treatment of SJL mice switch their T cells to form IgE-PF. A correlation between the enhancement of the IgE response and the formation of IgE-PF, and that between suppression of IgE response and formation of IgE-SF strongly suggest that IgE-binding factors (IgEBF) are involved in tile lgE response
in vivo. 2) Significance of oli.qosaccharides in
lhe I.qE-BF in their biologic activities. Major differences between the I g E - P F and IgE-SF are their carbohydrate moieties. IgE-PF has both
402
7e F O R U M D'IMMUNOLOGIE
sialidated N-linked oligosaccharide and O-linked oligosaccharide, while IgE-SF contains only O-linked oligosaccharide with galactose ~ N-acetylgalactosamine as terminal sugars [6]. Therefore, I g E - P F has affinity for lentil lectin and ConA, while IgE-SF has affinity for peanut agglutinin (PNA). We hypothesized that these oligosaccharides play an important role in the biologic activities of IgE-BF, because inhibition of assembly of N-linked oligosaceharides switches the same cells from the formation of IgE-PF to the formation of IgE-SF [6]. In addition to the 15-Kd I g E - B F described above, FOR.- T cells also produce the 60-Kd and 30-Kd lgE-BF. Some of these factors have either potentiating activity or suppressive activity; however, a correlation between the biologic activities and affinity for lectin does not apply for the 60-Kd and 30-Kd IgE-BF. The 30-Kd IgE-BF having affinity for PNA frequently lacked biologic activities [2, 4]. IgE suppressor factor (IgE-TsF) described by Suemura el al. [7] has a molecular weight of 6 0 K d or higher, and has affinity for IgE; however, this factor has affinity for lentil lectin. As will be described, the 60-Kd IgE-BF has multiple sites for N-linked oligosaccharides and O-linked oligosaccharides. Binding of IgE-TsF to lentil lectin appears to be due to the presence of a N-linked oligosaccharide, which is not included in the 15-Kd IgE-BF. Evidence has accumulated which suggests that the same FoR + T cells can produce both the 15-Kd IgE-PF and IgE-SF [8]. We predicted that the two factors share common precursor molecules. This hypothesis is supported by gene cloning of rodent IgE-BF. Using mBNA of a ratmouse T hybridoma, 23B6, which produces IgE-SF upon incubation with IgE, Martens el al. [9] succeeded in obtaining eDNA clones encoding rodent IgE-BF. Transfection of COS-7 monkey kidney cells with a eDNA clone, 8.3, resulted in the formation of the 60-Kd and l l - K d IgE-BF. The nucleotide sequence of the eDNA evoked the amino acid sequence of the
60-Kd IgE-BF. The factor represents a single polypeptide consisting of 556 amino acids with two potential sites for N-linked glycosylation and several potential sites for post-translational proteolytic cleavage. We speculate t h a t the l l-Kd IgE-BF from the transfected COS-7 cells is a cleavage product of the 60-Kd precursor molecule. An interesting finding was that both the 60-Kd and l l - K d IgE-BF from the eDNA clone had atlinity for lentil leetin, and both factors selectively potentiated the IgE response. It should be noted that hybridoma cells 23B6, from which mRNA was obtained for the construction of eDNA libraries, produced IgE-SF. The findings support the view that IgE-PF and IgE-SF may be encoded by the same mRNA, and biologic activities of the factors are decided b y post-translational glycosylation process. 3) FcR+ I' cells are mulli-/unclional regulalorg cells.
The cell source of IgE-BF is T cells with either Fcd~ or Fc-(R or both [8]. These cells respond to homologous IgE or interferon-like substances which are released from antigen-primed T cells. Even when FccR are not detectable, we imagine that the cells bear a small number of Fcr which may not be detectable by rosetting technique. This speculation is based on the fact that some Fc~lR § 1 6 2 ) cells respond to antibodies against IgE-BF, which cross-reacts with F e a r but not with Fc,fll, to form IgE-BF [2]. However, none of the interferon-like substance, IgE or anti-IgE-BF, determines the nature of IgE-BF formed. Under physiological conditions, the N-glycosylation of IgE-BF is controlled by two T-cell factors which either enhance or inhibit the N-glycosylation. The glycosylation-enhancing factor (GEF) is derived from Lyt-l+ T cells, and is a kallikrein-like enzyme with lectinlike properties [10]. Glycosylationinhibiting factor (GIF) is a fragment of phosphorylated lipomodulin, a phospholipase inhibitory protein [11]. It was found that unprimed FoR + T cells
R E G U L A T O R Y FcR from Lewis rats or BALB/c mice formed IgE-PF when they were incubated with IgE (or interferon) in the presence of GEF, but the same cells produced IgE-SF in the presence of G1F. In these systems, the source of I g E - P F / I g E - S F is not antigen-primed. Recently, however, we obtained an antigen-specific FcR + T-cell clone and antigen-specific T hybridomas which formed IgE suppressive factor upon incubation with antigen-pulsed macrophages. From the classical concept in cellular immunology, these cells may be called ~ IgE-specific suppressor T cells )). However, if one incubates the hybridomas with antigen-pulsed maerophages in the presence of GEF, the same cells produce IgE-PF. Since these cells bear FcyB, it is quite possible that they may form IgG-BF [12]. We hypothesize that F e b +, antigen-specific T cells are multifunctional, and could either suppress or enhance the IgE and IgG antibody responses depending on the environment of the cells.
]t~('/erC,qcSS. [1] 1SItlZAKA, X.,
SUEMU1RA, M,,
YODOI, J. & HIRASHIM~, M., Fed. Proe., 1981, 40, 2162.
403
[2] HUFF, T. F., YODOl, J., U~DE, T. & ISHIZAKA, [~., ,1. Immunol., 1984, 132, 406. [3] UEDE, T., HUFF, T. F. & ISHIZAKA, K., J. lmmunol., 1982, 129, 1384. [4] HIRASHIMA, M., YODOI, J. & ISHiZAK.% K., J. Immunol., 1980, 125, 2514. [5] UEDE, T. & ISHIZAKA, I(., J. Immunol., 1984, 133, 359. [61 YODOI, J., t~III~IASH 13IA, ~[. & ISmZt~KA, K., d. immunol., 1982, 128, 289. [7] SUEMURA, M., SHIIIO, O., DEGUcni, H., YAMAMUllA, Y., BSTTCHER, I. ~5 t(ISIIIMOTO, T., J. Immunol., 1981, 127, 465. [8] ISHIZAKA, K., Anll. Reo. Immunol., 1984, 2, 159. [9] M.~BTENS, C. L., HUFF, T. F., JARDIEU, P., TROUSTINE, M. L., COFFMAN, 1~. L., ISmZAKA, K. & MOORE, K. \u Proc. nat. Acad. Sci. (Wash.), 1985 (in press). [10l IWATA, M., MUNOZ, J. J. & IStlIZAKA, K., J. Immunol., 1983, 131, 1954. [11] U z o r , T., HmATA, F., HII/ASHIMA, M. & ]SHIZAKA, 1~., ,J. Immunol., 1983, 130, 878. [12] FRID3IA-N, W. H., RABOU/-~DINCOMBE, NEAUPORT-SAUTES, C. & GmLER, H., lmmunol. Rev.. 1981, 56, 51.
REGULATORY MECHANISM OF IgA AND lgE PRODUCTION by M. Adachi, N. Noro, T. Nagai and J. Yodoi I~slilule for Imrmmologg, Facullg o[ Medicine, Kyolo Universily, Kyoto, 606 (Japan) Inlroduclion. Accumulating evidence shows that T cells bearing class-specific Fc receptors (FOR) play an important role in isotypic regulation via releasing soluble factors [1, 2, 3]. These factors include IgG-binding factors (IgG-BF) reported by Fridman and his colleagues [21 and IgE-binding factors (IgE-BF) by lshizaka el al. [3, 4, 5]. IgG-BF and IgE-BF regulate IgG
and IgE responses, respectively, in vilro in a class-specific manner. Furthermore, both of the BF are produced by T cells bearing F e b of corresponding isotypes. Abnormal regulation of IgA production, which is important in immune responses in secreting organs, is observed in human diseases such as selective IgA deficiency and IgA nephropathy. In order to determine tile pathophysiological mechanism of these