Basic Immunology

Chronic lymphocytic leukamia

2012-01-10T02:04:00.000-08:00

Chronic lymphocytic leukemia (chronic lymphoid leukemia, CLL) is a monoclonal disorder characterized by a progressive accumulation of functionally incompetent lymphocytes. It is the most common form of leukemia found in adults in Western countries.
Onset is insidious, and it is not unusual for CLL to be discovered incidentally after a blood cell count is performed for another reason. Enlarged lymph nodes are the most common presenting symptom, but patients may present with a wide range of symptoms and signs.
Chemotherapy is not needed in CLL until patients become symptomatic or display evidence of rapid progression of disease. A variety of chemotherapy regimens are used in CLL. These may include nucleoside analogues, alkylating agents, and biologics, often in combination. Allogeneic stem cell transplantation is the only known curative therapy.

Lymph node (Secondary lymphoid organ)

2012-01-02T23:42:00.000-08:00

Lymph nodes are round or bean-shaped structures that are widely distributed throughout the body. Imbedded in connective tissue or fat, they are concentrated in the cervical, axillary, and inguinal regions – the neck, armpits, and groin, respectively. They are typically less than ½ inch in length, depending on the size of the animal. The lymph nodes filter the lymph before returning it to the veins. They are arranged so that all lymph has to pass through at least one node before returning to the veins.

Lymph nodes are enclosed by a capsule of connective tissue and comprised of several compartments called "lymph nodules." The nodules are masses of T-cells, B-cells, and macrophages. Macrophages are specialized cells that ingest and destroy foreign material. The nodules are separated by spaces called "lymph sinuses." The vessels that deliver unfiltered lymph are called "afferent vessels," and there are several per node. The lymph is then filtered for antigens and particulate matter, and an immune response is generated, if necessary. The filtered lymph leaves the node through one or two efferent vessels near an indentation called the "hilum." Blood vessels also enter and exit the node at the hilum.

Bone marrow (Primary lymphoid organ)

2012-01-02T23:39:00.000-08:00

Bone marrow is the soft material in the cavities of bones. It is a network of connective tissue fibers, fat cells, blood vessels, and blood-producing cells. Bone marrow produces both red and white blood cells, including the lymphocytes. Both T-lymphocytes and B-lymphocytes are produced in the bone marrow. The young T-cells move to the thymus for final development, but the B-cells remain in the bone marrow during maturation. Once the B-cells are fully developed in the bone marrow, they are also released into circulation and most of them take up residence in the secondary lymphatic organs.

The B-cells are white blood cells that are sensitive to antigens and produce antibodies against them. Antigens are any chemicals that produce an immune response in the body, such as toxins, foreign proteins, particulate matter, or bacterial cells. When an antigen is present, the B-cell becomes active and begins to produce antibodies against that antigen. Antibodies are special proteins that bind (attach) to antigens and mark them for destruction. Antibodies are antigen specific, and the immune system is able to remember each antigen it fights. Once a B-cell makes antibodies against a certain antigen, e.g., a bacteria, it keeps a memory of that antigen. If the antigen appears again, the B-cell can produce a large number of antibodies very rapidly. In this way, a second infection with that bacteria is often prevented.

Thymus (Primary Lymphoid Organ)

2012-01-02T23:34:00.000-08:00

Thymus is located beneath the breast bone. Those two lobes! It functions at its peak during adolescence producing specialized lymphocytes—T-cells and B-cells and dispatching them through the lymph vessels to the secondary organs. In very simple words, we can say its purpose is to initiate antibody formation
Immature thymocytes, also known as prothymocytes, leave the bone marrow and migrate into the thymus. Through a remarkable maturation process sometimes referred to as thymic education, T cells that are beneficial to the immune system are spared, while those T cells that might evoke a detrimental autoimmune response are eliminated. The mature T cells are then released into the bloodstream.

It all sounds complicated, i know! but keep in mind "thymus' role is to process lymphocytes, which are white blood cells".

Basic Structure of Antibodies

2012-01-01T23:40:00.001-08:00

Antibodies are heterodimers. Antibody molecdules have a
common structurehaving four peptide chains.
It contains two identical light (L) chains, polypeptides of about 25,000 molecular weight, and
two identical heavy (H) chains, large polypeptides of molecular weight around 50,000 or more.

Each light chain is bound to a heavy chain by a disulfide bond,
and by such noncovalent interactions as salt linkages, hydrogen bonds,
and hydrophobic bonds, to form a heterodimer (H-L).
Similar noncovalent interactions and disulfide bridges link the
two identical heavy and light (H-L) chain combinations to each other
to form the basic four-chain (H-L)2 antibody structure, a dimer of
dimers.

Definition of Antibodies

2012-01-01T23:39:00.000-08:00

Antibodies are the antigen binding protiens present on the B-cell and secreted by plasma cells.

Antigenicity and Immunogenicity

2012-01-01T23:37:00.000-08:00

Antigenicity and Immunogenicity are related but distinct immunologic properties makes it sometimes confused.
Immunogenicity is the ability to induce a humoral and/or cellmediated immune response.

A substance that induces a specific immune response is called an antigen,
it is more appropriately called an immunogen.

Antigenicity is the ability to combine specifically with the final products of the above responses.
Although all molecules that have the property of immunogenicity also have
the property of antigenicity, the reverse is not true.
Some small molecules, called haptens, are antigenic but incapable, by themselves,
of inducing a specific immune response.
They do not have immunogenicity.

Definition of Antigen

2012-01-01T23:30:00.000-08:00

Substrances that can be recognized by the immunoglobulin receptor or by the T cell receptor called antigens.

Immunology

2011-05-21T09:48:00.001-07:00

Immunology is study of immune system of body and all factors related to immunity.