Human Immunity and Blood

CSF is produced by the choroid plexus, NOT the arachnoid villi. Arachnoid villi are the site of CSF absorption into the venous sinuses. The other statements are correct: CSF leakage does cause headache (low pressure headache), neutrophils are normally absent (predominantly lymphocytes and monocytes), and CSF pH is slightly lower (more acidic) than blood pH.

Cellular marrow means the bone marrow is hypercellular, ruling out aplastic causes. PNH causes pancytopenia due to intravascular hemolysis with cellular marrow. Megaloblastic anemia shows ineffective erythropoiesis with cellular marrow. Myelodysplastic syndrome presents with pancytopenia and hypercellular marrow. Congenital dyserythropoietic anemia primarily affects erythropoiesis with macrocytic anemia but does not typically cause pancytopenia - it is the exception.

Diphtheria is a bacterial infection that primarily affects the throat and respiratory tract. The bacteria Corynebacterium diphtheriae produces toxins that damage throat tissues, creating a characteristic membrane. Blood, liver, and brain are not the primary sites of diphtheria infection.

Blood cancer (leukemia) involves uncontrolled proliferation of white blood cells (WBCs) in bone marrow. This crowds out healthy blood cells. RBCs carry oxygen, platelets help clotting, and hemoglobin is the oxygen-carrying protein in RBCs - none are the primary cancer source.

Anaphylaxis is a severe, potentially life-threatening IgE-mediated allergic reaction. IgE antibodies bind to mast cells and basophils, triggering release of histamine and other mediators that cause widespread vasodilation, bronchoconstriction, and can lead to circulatory shock and asphyxia. Orthopnea is breathing difficulty when lying flat.

Heparin is an anticoagulant substance produced primarily by mast cells, which are connective tissue cells containing granules with heparin and histamine. Mast cells release heparin as part of the inflammatory response and to prevent blood clotting. Other options are incorrect: fibroblasts produce collagen, plasmocytes are antibody-producing plasma cells, and adipocytes store fat.

Blood type O individuals have both anti-A and anti-B antibodies in their plasma because they lack A and B antigens on their red blood cells. Type AB has neither antibody, type A has anti-B, and type B has anti-A.

T8 cells refer to T lymphocytes that express the CD8 co-receptor, which are known as cytotoxic T cells. These cells are responsible for killing virus-infected cells, tumor cells, and damaged cells. T4 cells (CD4+) are helper T cells.

All three diseases are related to the lymphatic system. Hodgkin's disease is a cancer of the lymphatic system (lymphoma). Multiple myeloma is a cancer of plasma cells (which are derived from B lymphocytes in the lymphatic system). Chronic lymphocytic leukemia is a cancer of B lymphocytes.

Hodgkin's disease (Hodgkin lymphoma) is a cancer of the lymphatic system that specifically affects lymphocytes, which are a type of white blood cell. It does not primarily involve erythrocytes (red blood cells) or all leucocytes.

Antibodies are proteins produced by specialized immune cells called B lymphocytes (B cells). Neutrophils, basophils, and monocytes are other types of white blood cells, but they do not produce antibodies - neutrophils are phagocytes, basophils release inflammatory chemicals, and monocytes become macrophages.

O blood cells are called “universal”, meaning they can be transfused to almost any patient in need.

Blood group O individuals have both anti-A and anti-B antibodies in their plasma because they lack both A and B antigens on their red blood cells. This is why O is the universal donor but can only receive O blood. AB has neither antibody, A has anti-B, and B has anti-A.

Dendritic cells are the master regulators of immune system in pulp. When pulp is irritated, odontoblastic processes sense invasion and elicit requirement of dendritic cells which phagocytose invaders and present antigens to stimulate T-lymphocytes.

People with AB blood type are 'universal recipients' - they have no anti-A or anti-B antibodies in their plasma, so they can receive blood from any group (A, B, AB, or O). However, AB donors can only give to other AB recipients. The question specifically asks where AB donor blood can go.