Biomedical subjects

Sergey Yurasov

Publications and source records attributed to Sergey Yurasov.

5 recordsLinked to original sources

PubMed2006

Persistent expression of autoantibodies in SLE patients in remission.

A majority of the antibodies expressed by nascent B cells in healthy humans are self-reactive, but most of these antibodies are removed from the repertoire during B cell development. In contrast, untreated systemic lupus erythematosus (SLE) patients fail to remove many of the self-reactive and polyreactive antibodies from the naive repertoire. Here, we report that SLE patients in clinical remission continue to produce elevated numbers of self-reactive and polyreactive antibodies in the mature naive B cell compartment, but the number of B cells expressing these antibodies is lower than in patients with active disease. Our finding that abnormal levels of self-reactive mature naive B cells persist in the majority of patients in clinical remission suggests that early checkpoint abnormalities are an integral feature of SLE.

Adolescent↗

PubMed2006

A checkpoint for autoreactivity in human IgM+ memory B cell development.

Autoantibodies are removed from the repertoire at two checkpoints during B cell development in the bone marrow and the periphery. Despite these checkpoints, up to 20% of the antibodies expressed by mature naive B cells in healthy humans show low levels of self-reactivity. To determine whether self-reactive antibodies are also part of the antigen-experienced memory B cell compartment, we analyzed recombinant antibodies cloned from single circulating human IgM+ memory B cells. Cells expressing antibodies specific for individual bacterial polysaccharides were expanded in the IgM+ memory compartment. In contrast, B cells expressing self-reactive and broadly bacterially reactive antibodies were removed from the repertoire in the transition from naive to IgM+ memory B cell. Selection against self-reactive antibodies was implemented before the onset of somatic hypermutation. We conclude that a third checkpoint selects against self-reactivity during IgM+ memory B cell development in humans.

Antigens, Bacterial↗

PubMed2005

Defective B cell tolerance checkpoints in systemic lupus erythematosus.

A cardinal feature of systemic lupus erythematosus (SLE) is the development of autoantibodies. The first autoantibodies described in patients with SLE were those specific for nuclei and DNA, but subsequent work has shown that individuals with this disease produce a panoply of different autoantibodies. Thus, one of the constant features of SLE is a profound breakdown in tolerance in the antibody system. The appearance of self-reactive antibodies in SLE precedes clinical disease, but where in the B cell pathway tolerance is first broken has not been defined. In healthy humans, autoantibodies are removed from the B cell repertoire in two discrete early checkpoints in B cell development. We found these checkpoints to be defective in three adolescent patients with SLE. 25-50% of the mature naive B cells in SLE patients produce self-reactive antibodies even before they participate in immune responses as compared with 5-20% in controls. We conclude that SLE is associated with abnormal early B cell tolerance.

Adolescent↗

PubMed2005

B-cell tolerance checkpoints in healthy humans and patients with systemic lupus erythematosus.

Antibodies are protective effector molecules in the body's immune defense against pathogens. However, if directed against the body's own tissues or organs, antibodies can also play a role in the pathogenesis of autoimmune disease. Here, we discuss our data on how autoreactive antibodies are regulated in healthy humans and how a failure to establish self-tolerance during early B-cell development in patients with systemic lupus erythematosus may predispose to the development of this autoimmune disease.

B-Lymphocyte Subsets↗

PubMed2003

Predominant autoantibody production by early human B cell precursors.

During B lymphocyte development, antibodies are assembled by random gene segment reassortment to produce a vast number of specificities. A potential disadvantage of this process is that some of the antibodies produced are self-reactive. We determined the prevalence of self-reactive antibody formation and its regulation in human B cells. A majority (55 to 75%) of all antibodies expressed by early immature B cells displayed self-reactivity, including polyreactive and anti-nuclear specificities. Most of these autoantibodies were removed from the population at two discrete checkpoints during B cell development. Inefficient checkpoint regulation would lead to substantial increases in circulating autoantibodies.

Antibodies, Antinuclear↗