Human Immunity and Blood

The Rh system apparently is genetically much more complex 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 2 antigens.

Since, type O blood normally lacks both A and B antigens, it will not be recognized as an alien type by the blood of anyone. As a result, anyone usually can be transfused with O blood without concern about rejection for this blood group.

Platelets (thrombocytes) are the smallest type of blood cells, which play an important role in blood clotting. When bleeding occurs, the platelets swell and clump together and form a sticky plug, which helps to stop the bleeding.

It is the process of transferring blood or blood based products from one person into the circulatory system of another. Blood transfusions can be life saving in some situations such as massive blood loss due to trauma, or can be used to replace blood lost during surgery. Blood transfusions may also be used to treat a severe anaemia or thrombocytopenia caused by a blood disease.

The antigens expressed on the surface of red blood cell determine an individual's blood group. Blood group antigens are either sugars or proteins, and they are attached to various components in the red blood cell membrane.

Blood group O individuals do not have either A or B antigens on the surface of their RBCs, but their blood serum contain IgM anti A antibodies and anti B antibodies against the A and B blood group antigens. Therefore, an individual of blood group O can receive blood only from a blood group O individual, but can donate blood to individuals of any ABO blood group.

They are white blood cells present in the vertebrate immune system. The three major types of lymphocytes are T cells, B cells and natural killer (NK) cells. T cells are involved in cell mediated immunity,whereas B cells are primarily responsible for humoral immunity. NK cells help in defending the host from both tumors and virally infected cells.

 The nuclei of lymphocytes are usually round but may be slightly indented.

 AB blood group has both antigens A and B but no antibodies

 Lymphocytes are kind of white blood cells that are important in immune system

 Antibodies are produced by B lymphocytes

  Abnormally increased concentration of haemoglobin in the blood is polycyathemia

Platelets are produced in the bone marrow, the same as the red cells and most of the white blood cells. Platelets are produced from very large bone marrow cells called megakaryocytes.

Antibodies are produced by specialised white blood cells called B lymphocytes (or B cells). When an antigen binds to the surface of a B-cell, it stimulates the B cell to divide and mature into a group of identical cells called a clone.

Thromboplastin is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin.