Human Immunity and Blood

MHC class I presents epitopes to killer T-cells, also called cytotoxic T lymphocytes (CTLs).

Anergy is a term in immunobiology that describes a lack of reaction by the body's defense mechanism to foreign substances. It consists of a direct induction of peripheral lymphocyte tolerance.

Schaumann bodies are observed in sarcoidosis. Schaumann bodies are calcium and protein inclusions inside Langhans giant cells (fused epithelial cells) as part of granuloma.

MHC class I occurs in all nucleated cells, except RBCs.

Active multiplication of bacteria in the blood with the production of toxins is called septicemia.

Blood cells are produced in the bone marrow, specifically the spongy tissue inside large bones. This process, called hematopoiesis, generates red blood cells, white blood cells, and platelets. The spleen stores and filters blood but doesn't produce blood cells.

The T cell receptor or TCR is a molecule found on the surface of T lymphocytes, that is responsible for recognising antigens bound to major histocompatibility complex (MHC) molecules. Co-receptor of T-cells are:

1. On helper T cells, this co-receptor is CD4 that is specific for MHC class II.
2. On cytotoxic T cells, this co-receptor is CD8 that is specific for MHC class I.

Transferrins are found in serum. These are proteins with antibacterial activity and are iron-binding blood plasma glycoproteins that control the level of free iron in biological fluids. 

Monocytes are the largest white blood cells (12-20 micrometers). They are agranular leukocytes that differentiate into macrophages when they migrate into tissues. Basophils and acidophils are much smaller granulocytes.

Antigens on the surface of red blood cells determine blood groups and are inherited genetically. The ABO and Rh blood group systems are based on specific antigens present on RBCs. Hemoglobin is the oxygen-carrying protein, antibodies are in plasma, and 'blood groups' is the result, not the factor.

Antibodies are produced by B lymphocytes (B cells), a type of white blood cell that is part of the adaptive immune system. Monocytes are phagocytes that become macrophages, basophils release histamine in allergic responses, and eosinophils combat parasitic infections - none produce antibodies.

They are produced in the bone marrow. They have a large kidney-shaped nucleus. The cytoplasm is more than in lymphocytes. They number 100 to 700 per cubic mm. They function as tissue macrophages feeding on damaged tissues.

Primary haemostasis initially involves vasoconstriction in response to vascular damage which limits blood loss, and subsequent platelet adhesion to the damaged area and activation due to exposure of subendothelial matrix.

Eosinophils have a bilobed nucleus (two lobes connected by a narrow strand of chromatin). Their granules are considered to be lysosomes. Eosinophils actively phagocytize complexes formed by the action of antibodies on antigens (foreign substances).

They are circulating immature macrophages or dendritic cells.