Tsuyoshi Sakane

Anti-DNA antibody production by CD5+ and CD5- B cells of patients with systemic lupus erythematosus.

Although the presence of anti-DNA antibody is a hallmark of systemic lupus erythematosus (SLE), neither the subsets of B cells that secrete anti-DNA antibody nor the stimuli responsible for the induction of anti-DNA secretion is known. In particular, the role of CD5+ B cells in human SLE, a distinct subpopulation of antibody-secreting cells shown previously to be a source of anti-DNA antibody in murine models of SLE, is unknown. To approach these questions, we developed a sensitive enzyme-linked immunospot (ELIspot) assay to measure spontaneous secretion of antibody to single-stranded (ss) DNA, double-stranded (ds) DNA, tetanus toxoid, and polyclonal immunoglobulin (Ig) by purified CD5+ and CD5- B cells of 15 SLE patients and 15 healthy control subjects. The B cells of only 1 of 15 healthy subjects secreted a significant level of anti-ssDNA antibody, and none secreted anti-dsDNA. By contrast, in the majority of SLE patients both CD5+ and CD5- B cells secreted IgG and/or IgM anti-ssDNA as well as anti-dsDNA antibody. Further analysis of the anti-ssDNA response revealed that the level of IgG and IgM anti-DNA antibody secretion by CD5- B cells correlated closely with the level of polyclonal Ig production by the same subpopulation (r = 0.81 and 0.70, respectively). In contrast, production of anti-DNA by CD5+ B cells occurred independently of polyclonal Ig production by both CD5+ and CD5- B cell subpopulations. These results suggest that in human SLE there exist two anti-DNA antibody-producing B cell subpopulations with distinct induction mechanisms: one (CD5+), which independently secretes anti-DNA, and another (CD5-), which produces anti-DNA as an apparent consequence of polyclonal B cell activation.

The effect of aging on cutaneous lipid peroxide levels and superoxide dismutase activity in guinea pigs and patients with burns

Cutaneous lipid peroxide levels and superoxide dismutase (SOD) activity in non-aged and aged guinea pigs were measured between 15 min and 7 days after experimental infliction of burns. Skin burns on non-aged and aged patients were also subjected to these assays. In non-aged guinea pig skin burns, lipid peroxide levels increased from 24 hr to the fourth day after the burn infliction, while SOD activity did not increase but showed a slight decrease 12 hr and 24 hr post-burn. On the other hand, while the aged group showed a more increase in skin lipid peroxide levels compared to that seen in non-aged mice, skin SOD activity began to decrease from 30 min post-burn, the maximum decrease being reached on the second day. The activity did not return to normal by the 7th day. In non-aged patients skin burns showed increases in both lipid peroxide levels and SOD activity, while in aged patients, though they showed a marked increase in lipid peroxide levels, SOD activity remained unchanged. The present study indicated that, although in our recent study, skin SOD activity of healthy elderly people was found to be comparable to that in non-aged individuals, the capacity for induction of SOD activity under oxygen stress differed with age in both guinea pig and human burn sufferers. Furthermore, this induction capacity seemed to vary from species to species.

Induction of excessive B cell proliferation and differentiation by an in vitro stimulus in culture in human systemic lupus erythematosus.

B cell hyperactivity present in the body in patients with systemic lupus erythematosus (SLE) can be detectable via almost any measure of B cell function. Nonetheless, the basis for the B cell hyperactivity is difficult to study in vitro. In this study, we have obtained the resting B cells from patients with entirely inactive SLE by collecting them sedimenting in a high density fraction on a Percoll density gradient. These resting SLE B cells proliferated in vitro at a higher rate than normal B cells when exposed to Staphylococcus aureus Cowan I (SAC). In addition, significant proliferation was observed earlier in the course of culture in SLE patients than in normal controls. Moreover, the SLE resting B cells, once triggered by SAC produced abnormally high numbers of immunoglobulin-secreting cells in response to T cell-derived soluble factors. There was less frequency of circulating Leu 1+ B cells in the SLE patients than in normal controls. Moreover, not only Leu 1+ B cells but also Leu 1- B cells of SLE patients were more responsive to SAC than those of normal controls. The results indicate that the B cell hyperactivity in human SLE can be induced by in vitro stimuli, and may not be limited to the Leu 1+ B cell subset.

ALTERED T-CELL SUBSETS IN RHEUMATOID ARTHRITIS

まず, phytohemagglutinin (PHA), concanavalin A (Con A)およびpokeweed mitogen (PWM)がヒトにおいては胸腺由来(T)リンパ球のみを刺激することを明らかにし,併せてPHAおよびCon Aに対する反応性の差異からT細胞subclassを分別した.ウシ血清アルブミン濃度勾配遠心法によりリンパ球を細分画すると,中比重分画に集まる細胞はT細胞であつたが,高比重分画は大部分骨髄由来(B)リンパ球で構成された. PHA, Con A, PWMはT細胞分画を強く刺激したのに対し高比重分画ではほとんど反応せず,また, T, B両細胞を含む条件下でこれらmitogenに反応したリンパ球は著明なEロゼットを形成したことから, PHA, Con A, PWMいずれに対する反応もT細胞機能として把握されうることを知つた.さらに, PHAおよびCon Aに最も強く反応するリンパ球を異なるT細胞分画に認めたことは, PHAとCon Aでは反応するpopulationにずれがあり,同一でないことを示唆している.次いで,慢性関節リウマチ(RA)にみられる細胞性免疫の異常状態を知る目的で, RA患者リンパ球の各種mitogenに対する反応をdose-responseの関係から求めた. PHAについてはほぼ全ての濃度領域において明らかな反応低下を認め, Con Aでも低濃度から至適濃度に至る領域で著しい低下を示したが,さらに高濃度のCon Aに対しては正常反応を呈した. PWMに対する反応性は全濃度領域で正常を示した.これは, PHAおよびCon Aに反応するT細胞のsubclassが量的ないし質的に偏移した結果と考えられる.