Human Immunity and Blood

Poor T-cell responses specific for the leprosy bacillus, prevent the host from mounting a killing response and the bacilli grow profusely.

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.

Macrophages are large-sized cells which are phagocytic in nature and engulf foreign particles, digesting them with the help of their lysosomal enzymes.

Hepatic stellate cells probably have a role in antigen presentation and stimulation of natural killer cells. These cells are found in the perisinusoidal space (a small area between the sinusoids and hepatocytes).

Idiotype defines the surface and properties of the variable region and of antigen receptors of T cells. Thus, determining the antigen specificity and therefore the idiotope of the molecule.

Platelets help in the clotting of the blood. Thus, preventing the excessive loss of blood during an injury.

IgM is the first antibody isotype produced by B cells during the initial immune response to an antigen, serving as the primary line of defense before class switching to IgG.

IgG is the most abundant immunoglobulin in the human serum, accounting for approximately 75-80% of all antibodies.

NK cells are spontaneously cytotoxic for certain tumor cell lines and express CD16, the low affinity Fc gamma RIII. Beige mice congenitally lack NK cells and die with spontaneous tumors earlier than their non-deficient heterozygous+/bg littermates.

Prostaglandins and thromboxanes are newly synthesised by the mast cell using the cyclo-oxygenase pathway. The leukotrienes B4, C4 and D4 (slow reacting substance of anaphylaxis, SRS-A) are also newly synthesised by the mast cell, in this instance using the lipoxygenase pathway.

Sodium cromoglycate is a mast cell stabiliser,  which makes the cell resistant to triggering. It is thus able to block type I hypersensitivity.

Carcinoembryonic antigen (CEA) is an oncofetal antigen but there is a high incidence of false positives. Reappearance of CEA after surgical removal of the primary tumor is strongly indicative of fresh tumor growth.

Anti-CD33 is highly specific for myeloid leukemias in relation to other hematopoietic stem cells and has been used successfully for bone marrow purging and also for therapy.

Failure of regulatory T-cells would release the T-helper for direct stimulation by antigen. This statement is therefore incorrect, since this would not be a bypass of the T-helpers.

They are protective proteins which protect the body from ill effects of poisonous (toxic) substances and pathogenic invaders (virus, bacteria and other pathogens) by destroying the toxins and invaders. Important defence proteins are antibodies or immuno-globulins produced by lymphocytes in vertebrates. Interferon protects cells from the attack of viruses. Thrombin and fibrinogen form blood clots to prevent loss of blood and infection at sites of injuries. Certain proteins, called exploitive proteins, are normally toxic, but they may play a defensive role under certain conditions.