Human Immunity and Blood

Individuals with HLA-DR2 are more at risk of developing multiple sclerosis than those with other HLA-DR specificities. Thus, a higher frequency of HLA-DR2 is found in MS patients versus the normal population.

In order to be T-cell epitopes, i.e. peptides, they must be derived by antigen processing. Qualitative and/or quantitative alterations in processing can lead to greatly increased production of cryptic peptides and thus, may trigger autoimmune disease.

This statement is false. The 'natural antibodies' are low affinity IgM.

The mutation of the antibody variable region genes in B-cells in the germinal center produces a range of antibody affinities, and those B-cells bearing higher affinity antibody will be favourably selected for further stimulation by the antigen.

Recurrent fetal loss is characteristic of the antiphospholipid syndrome. In the experimental situation, passive transfer of cardiolipin antibodies into mice also results in recurrent fetal loss.

Tolerogen is a substance that invokes a specific immune non-responsiveness due to its molecular form. If its molecular form is changed, a tolerogen can become an immunogen.

Immunoglobulin M is a basic antibody that is produced by B cells. It is the primary antibody against A and B antigens on red blood cells. IgM is by far  physically the largest antibody in the human circulatory system. It is the first antibody to appear in response to initial exposure to antigen.

A native antigen is an antigen that is not yet processed by an APC to smaller parts. T cells cannot bind native antigens, but require that they be processed by APCs, whereas B cells can be activated by native ones.

Factor IX or Christmas factor is one of the serine proteases of the coagulation system; it belongs to peptidase family S1. Deficiency of this protein causes hemophilia B.

Kupffer cells, are specialized macrophages located in the liver lining the walls of the sinusoids that form part of the reticuloendothelial system.

Platelets, also known as thrombocytes, are cell fragments in the blood that aggregate at the site of a wound to form a clot. RBCs carry oxygen, and WBCs are primarily involved in immune defense.

Lymph is essentially blood plasma that has leaked out of capillaries. It lacks red blood cells (which are too large to pass through vessel walls) but contains a higher concentration of certain white blood cells (lymphocytes).

Individuals with blood type AB are considered universal recipients because their red blood cells have both A and B antigens, meaning they do not produce antibodies against A or B blood types.

The liquid component of blood, i.e. plasma is the most abundant substance in blood. 

The Rh system apparently is much more complex genetically since it involves 45 different antigens on the surface of red cells that are controlled by 2 closely linked genes on chromosome 1. In most cases, the ABO system is controlled by only two antigens.