PMID- 11412303 OWN - NLM STAT- MEDLINE DCOM- 20010719 LR - 20190513 IS - 0019-2805 (Print) IS - 1365-2567 (Electronic) IS - 0019-2805 (Linking) VI - 103 IP - 2 DP - 2001 Jun TI - Specific immunoglobulin E responses in ZAP-70-deficient patients are mediated by Syk-dependent T-cell receptor signalling. PG - 164-71 AB - ZAP-70 deficiency is a rare primary immunodeficiency characterized by the absence of peripheral CD8+ T cells and defects in T-cell receptor (TCR) signalling. T cells in ZAP-70-deficient patients are assumed to have no helper functions for B-cell immunoglobulin synthesis, whereas the patients rarely have antigen-specific antibodies. We experienced a ZAP-70-deficient patient, who had immunoglobulin E (IgE) antibodies specific to food allergens, and we investigated the mechanisms of switching to IgE in the patient. Peripheral blood mononuclear cells from the patient did not proliferate upon stimulation with the antigens but produced distinct levels of interleukin-4 (IL-4). Cell sorting analysis indicated that the cells that produced IL-4 in response to the antigens were enriched in CD4+ T cells. Purified CD4+ T cells from the patient produced IL-4 and expressed CD40L upon stimulation with anti-CD3. Moreover, CD4+ T cells pretreated with anti-CD3 induced mature epsilon transcript on naive B cells. Since the results indicated that there remained sufficient T-cell receptor (TCR)-signalling in the patient's T cells to exert antigen-specific IgE switching on B cells, we next investigated the expression of the ZAP-70-homologous kinase Syk. Syk was present in high levels in patient's CD4+ T cells and was tyrosine-phosphorylated after TCR stimulation. Inhibition of Syk by piceatannol resulted in decreased production of IL-4 and expression of CD40L on patient's CD4+ T cells. Moreover, Syk was expressed on all human T-cell leukaemia virus (HTLV-1)-transformed T-cell lines derived from peripheral blood of the patient, whereas it was low or undetectable in control lines. It was therefore concluded that specific IgE responses in the patient were most likely to be mediated by Syk-dependent TCR-signalling. FAU - Toyabe, S AU - Toyabe S AD - Department of Pediatrics, Niigata University School of Medicine, Asahimachi, Niigata, Japan. toyabe@med.niigata-u.ac.jp FAU - Watanabe, A AU - Watanabe A FAU - Harada, W AU - Harada W FAU - Karasawa, T AU - Karasawa T FAU - Uchiyama, M AU - Uchiyama M LA - eng PT - Case Reports PT - Journal Article PL - England TA - Immunology JT - Immunology JID - 0374672 RN - 0 (Allergens) RN - 0 (Enzyme Precursors) RN - 0 (Intracellular Signaling Peptides and Proteins) RN - 0 (Receptors, Antigen, T-Cell) RN - 147205-72-9 (CD40 Ligand) RN - 207137-56-2 (Interleukin-4) RN - 37341-29-0 (Immunoglobulin E) RN - 42HK56048U (Tyrosine) RN - EC 2.7.10.1 (Protein-Tyrosine Kinases) RN - EC 2.7.10.2 (SYK protein, human) RN - EC 2.7.10.2 (Syk Kinase) RN - EC 2.7.10.2 (ZAP-70 Protein-Tyrosine Kinase) RN - EC 2.7.10.2 (ZAP70 protein, human) SB - IM MH - Allergens/immunology MH - B-Lymphocytes/immunology MH - CD4-Positive T-Lymphocytes/immunology MH - CD40 Ligand/metabolism MH - Enzyme Precursors/*immunology MH - Female MH - Food MH - Humans MH - Immunoglobulin E/*biosynthesis MH - Infant MH - Interleukin-4/biosynthesis MH - Intracellular Signaling Peptides and Proteins MH - Phosphorylation MH - Protein-Tyrosine Kinases/*deficiency/*immunology MH - Receptors, Antigen, T-Cell/*immunology MH - Severe Combined Immunodeficiency/*immunology MH - Signal Transduction/immunology MH - Syk Kinase MH - Tyrosine/metabolism MH - ZAP-70 Protein-Tyrosine Kinase PMC - PMC1783225 EDAT- 2001/06/20 10:00 MHDA- 2001/07/20 10:01 PMCR- 2002/06/01 CRDT- 2001/06/20 10:00 PHST- 2001/06/20 10:00 [pubmed] PHST- 2001/07/20 10:01 [medline] PHST- 2001/06/20 10:00 [entrez] PHST- 2002/06/01 00:00 [pmc-release] AID - imm1246 [pii] AID - 10.1046/j.1365-2567.2001.01246.x [doi] PST - ppublish SO - Immunology. 2001 Jun;103(2):164-71. doi: 10.1046/j.1365-2567.2001.01246.x.