Hideyuki Masaki

Arthritis and pneumonitis produced by the same T cell clones from mice with spontaneous autoimmune arthritis

SKG mice, a newly established model of rheumatoid arthritis (RA), spontaneously develop autoimmune arthritis accompanying extra-articular manifestations, such as interstitial pneumonitis. To examine possible roles of T cells for mediating this systemic autoimmunity, we generated T cell clones from arthritic joints of SKG mice. Two distinct CD8(+) clones were established and both showed in vitro autoreactivity by killing syngeneic synovial cells and a variety of MHC-matched cell lines. Transfer of each clone to histocompatible athymic nude mice elicited joint swelling and histologically evident synovitis accompanying the destruction of adjacent cartilage and bone. Notably, the transfer also produced diffuse severe interstitial pneumonitis. Clone-specific TCR gene messages in the inflamed joints and lungs of the recipients gradually diminished, becoming hardly detectable in 6-11 months; yet, arthritis and pneumonitis continued to progress. Thus, the same CD8(+) T cell clones from arthritic lesions of SKG mice can elicit both synovitis and pneumonitis, which chronically progress and apparently become less T cell dependent in a later phase. The results provide clues to our understanding of how self-reactive T cells cause both articular and extra-articular lesions in RA as a systemic autoimmune disease.

CD3 down‐regulating factor in sera and culture supernatants of leukaemic cells from patients with adult T cell leukaemia

Immunological abnormality of T lymphocytes in patients with adult T cell leukaemia (ATL) is characterized by abnormal expression of the 55 kD chain of the receptor for interleukin 2 (IL‐2R/p55) (Tac), and the down‐regulation of CD 3 expression. Using serum and culture supernatants of leukaemic cells from ATL patients (Group A) whose CD 3 expression was down‐regulated and those (Group B) whose CD 3 was not low, the possible mechanism of CD 3 down‐regulation on ATL cells was discussed. When PBMC from normal individuals were cultured with sera from ATL patients for 24 h, CD 3 expression revealed by mean fluorescent intensity (MFI) was down‐regulated by sera from ATL patients in Group A (MFI: Pt 1 = 51.6 ± 4.5, Pt 2 = 48.0 ± 6.9, control = 96.5 ± 6.6), not by sera from patients in Group B (MFI: Pt 3 = 105.5 ± 7.9, Pt 4 = 102.5 ± 8.3, control = 96.5 ± 6.6). When normal PBMC were cultured with supernatants of leukaemic cells from ATL patients in Group A, this CD 3 down‐regulating activity was also detected (MFI: Pt 1 = 78.0 ± 10.2, Pt 2 = 70.6 ± 8.7, control = 94.0 ± 6.6). By using gel‐chromatography, the fractionated supernatants from ATL patients in Group A decreased CD 3 expression of normal PBMC significantly (MFI: Pt 1 = 22.9 ± 5.8, Pt 2 = 28.8 ± 7.4, control = 92.1 ± 9.6). This CD 3 down‐regulating activity in fractionated supernatant was not inhibited by any lymphokine antibodies, anti‐IL‐1α antibody (Ab), anti‐IL‐1B Ab, anti‐IL‐2 Ab, anti‐IL‐3 Ab, anti‐IL‐4 Ab, anti‐IL‐6 Ab, anti‐TNF‐α Ab and anti‐IFN‐γ Ab. Any known cytokines (IL‐1, IL‐2, IL‐3, IL‐4, IL‐6, TNF‐α and IFN‐γ) could not modulate CD 3 expression of normal PBMC. These findings suggested that there are novel factor(s) with CD 3 down‐regulating activity in the serum and culture supernatant of ATL patient and those factor(s) are involved in progression of ATL.

Induction of specific and flavivirus—Cross-reactive CTLs by immunization with a single dengue virus-derived CTL epitope peptide

Specificities of cytotoxic T lymphocyte (CTL) effector cells induced in BALB/c mouse by immunization with the single modified CTL epitope peptide derived from NS3 of dengue virus types 1 and 3, or that of dengue virus types 2 and 4 were examined. The effector cells included CTLs specific for the epitope peptide used for immunization and those cross-reactive to epitope peptides of other flaviviruses. A CTL clone, 2F7, was established from the effector cells. The clone 2F7 was specific for the epitope peptide used for immunization. Recognition by the effector cells was remarkably impaired by amino acid substitutions at positions 3, 5, and 6 of the epitope peptides. These results indicate that immunization with a single CTL epitope peptide of dengue viruses induces serotype-specific CTLs as well as CTLs cross-reactive to the other flaviviruses, and that the a.a. residues at positions 3, 5, and 6 are critical for cross-reaction.

Induction of anti-idiotypic T cells through a network mechanism

BALB/c mouse T cells that recognized the idiotype expressed on M104E(mu, lambda 1) were induced by immunization with Dextran B-1355. T cells derived from mice immunized with 1 mg of Dextran B-1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or smaller amounts of Dextran B-1355 did not. BCL1Id, which had an identical isotype, did not induce proliferation of T cells. The T cell proliferative response against the idiotype on M104E required macrophages as antigen-presenting cells. The proliferative response was inhibited when antigen-presenting cells were treated with NH4Cl or chloroquine, which are antigen-processing inhibitors. These results indicate that anti-idiotypic T cells which recognized processed idiotopes could be induced physiologically through a network mechanism.

Generation of Helper T Cells That Recognize a Cross-Reactive Idiotype through a Network Mechanism

T cells that recognize the cross‐reactive idiotype expressed on the heavy (H) chain of M104E (IgM, λ1) were induced in BALB/c mice by immunization with Dextran B‐1355. T cells derived from mice immunized with 1 mg of Dextran B‐1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or lesser amounts of Dextran B‐1355 did not. BCLiId, which had an immunoglobulin isotype identical to M104E, did not induce proliferation of the T cells. These T cells also proliferated against J558 (IgA, λ1) which shared the cross‐reactive idiotype of the anti‐a (1—>3) glucosidic linkage antibody with M104E on the H chain. The T cells proliferated more efficiently against F(ab)2‐104E, Fab‐104E and H104E, the H chain of M104E, than against intact M104E. The T cell proliferative response against the idiotype on M104E or even H104E required macrophages as antigen‐presenting cells (APC) and the response was inhibited when APC were treated with NH4CI or chloroquine, inhibitors of antigen processing. Moreover, anti‐CD4 antibody or anti‐Ia antibody inhibited the proliferative response. These results indicated that anti‐idiotypic T cells of the helper type, which recognized a cross‐reactive idiotype associated with la molecules in processed form, could be induced physiologically through a network mechanism.