Human Immunity and Blood

Leukemia is a cancer of blood-forming tissues, primarily originating in bone marrow where abnormal white blood cells are produced. While it affects blood cells, the root cause and primary site is bone marrow dysfunction.

AB blood group is the universal recipient because it has both A and B antigens on red blood cells but no anti-A or anti-B antibodies in plasma. This allows AB individuals to receive blood from any ABO group (A, B, AB, or O) without antibody-mediated rejection. Types A, B, and O can only receive from their own type or O (universal donor).

Like cytotoxic T-cells, NK cells can inhibit viral replication by killing the host cell. The difference is that cytotoxic T-cells have a receptor for a specific T-cell epitope whereas NK cells have a broader specificity.

These amoeboid cells are found in the liver sinusoid and help to remove the toxic material from blood.

Haemoglobin is the red pigment that gives the red blood cells their colour. This is the correct answer. Platelets help in the blood clotting during cuts or wounds. 

Veiled cells are immature dendritic cells found in blood. 

sPLA2 (Secreted phospholipases A2) have been shown to promote inflammation in mammals by catalysing the first step of the arachidonic acid pathway by breaking down phospholipids.

C3b and, to a lesser degree, C4b molecules are opsonins.

Factor H is a member of complement activation family.

Mast cells express a high-affinity receptor (FcεRI) for the Fc region of IgE antibodies.

MPOs are expressed in neutrophil granulocytes. 

Class II HLA are membrane-bound glycoproteins that are restricted to macrophages and lymphocytes.

Platelets (thrombocytes) are the blood components responsible for clotting - they gather at wound sites, release clotting factors, and form platelet plugs. RBCs carry oxygen, lymphocytes are white blood cells for immunity, and monocytes are also white blood cells that fight infection but don't directly clot blood.

The correct answer is 'any blood group' because persons with blood group AB are called 'universal recipients' - they have both A and B antigens on their red blood cells and no anti-A or anti-B antibodies. This means they can safely receive blood from any blood group (A, B, AB, or O) without having a transfusion reaction.

The correct answer is white blood cells (leukocytes), which are the cells in the human body that fight infection. They are part of the immune system. Red blood cells carry oxygen, plasma is the fluid component, and hemoglobin is the oxygen-carrying protein in red blood cells.