Recognition of a peptide antigen by heat shock-reactive gamma delta T lymphocytes

Article Abstract:

T lymphocytes have a receptor, known as the T cell receptor (TCR), which binds antigens, molecules are recognized by the immune system as foreign. There are two types of TCR, those that contain alpha and beta chains, and those that contain gamma and delta chains. The TCR that contains alpha and beta chains recognizes antigens that have been processed into peptide fragments. The TCR that contains gamma and delta chains has now been shown to also recognize small processed peptides. This was demonstrated using laboratory-produced synthetic peptides of a protein, the 65-kD heat shock protein (Hsp65), present in mycobacteria. Mycobacteria are a group of bacteria including those that cause tuberculosis and leprosy. One of the peptides of Hsp65 stimulates cells that are known to respond in arthritis. Arthritis is thought to be an autoimmune disease, where a molecule that is a normal part of the body is recognized as foreign and an immune response is elicited. Mycobacteria are known to trigger autoimmune responses. The peptide that was recognize in Hsp65 was shown to be similar to heat shock proteins present in all species examined. Throughout evolution this portion of the protein in mycobacteria and in mammals has remained similar. Therefore, the protein in mycobacteria reacts with the normal protein and causes an autoimmune response. Cells that contain the TCR gamma and delta are thought to be involved in rheumatoid arthritis. The ability of these cells to respond to peptides of the heat shock proteins in mycobacteria supports the association between mycobacteria and autoimmune disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Rheumatoid arthritis, T cell antigen receptors, Arthritis, T cells, Mycobacterial infections, Mycobacterium infections

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Induction of type I diabetes by Kilham's rat virus in diabetes-resistant BB/WOR rats

Article Abstract:

Type I diabetes mellitus is an autoimmune disease, meaning that the body's immune system recognizes normal tissue as foreign and an immune response is mounted against that tissue. The reason why this happens is not understood. Diabetes mellitus occurs spontaneously in a particular strain of BB/WOR laboratory rats. A virus has been identified from a diabetic BB/WOR rat which causes diabetes in other BB/WOR rats that are genetically resistant to diabetes. This virus is known as Kilham's rat virus (KRV). Molecules of the virus were sought in the beta cells in the pancreas, which produce insulin, but were not found. It was thought that the viral molecules might have altered the cells so as to provoke an autoimmune response, but this does not appear to occur. However, destruction of the beta cells occurred when the islets of the pancreas were infiltrated with lymphocytes, indicating that an autoimmune reaction was indeed occurring. The mechanism of disease does not appear to involve the direct infection of the beta cells by the virus, but is rather indirect, involving stimulation of immune cells. This study showed that a virus could induce type I diabetes in genetically susceptible rats by an indirect mechanisms and not by infection of the beta cells themselves. This mechanism might also occur in genetically susceptible humans. (Consumer Summary produced by Reliance Medical Information, Inc.)

Models, Diabetes, Diabetes mellitus

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Detection of a human intracisternal A-type retroviral particle antigenically related to HIV

Article Abstract:

Sjogren's syndrome is characterized by dryness of the mouth and eyes. The salivary and lacrimal glands (near the eyes) do not function properly, and there is infiltration of the glands with lymphocytes, a type of white blood cell involved in the immune response. Sjogren's syndrome is an autoimmune disease, in which the body mounts an immune response against a body component that should not be recognized as foreign by the immune system. Patients with Sjogren's syndrome have clinical symptoms similar to those in patients with diseases induced by the human immunodeficiency virus (HIV), including AIDS. Approximately 30 percent of the patients with Sjogren's syndrome have antibodies in the blood that react with HIV. A virus was grown from tissue from the salivary gland of patients with Sjogren's syndrome. The virus is related to HIV but has its own distinctive characteristics. Further study will be necessary to show if this virus causes Sjogren's syndrome. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, HIV (Viruses), HIV, Identification and classification, Sjogren's syndrome, Retroviruses, Mouth diseases

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