Human Immunity and Blood

Gaucher's disease is characterised by deposition of keratin in reticulo endothelial cells.

Zone of infection is characterised by polymorphonuclear leukocytes.

Basophils are the rarest white blood cells, comprising only 0.5-1% of total WBC count. Neutrophils are most abundant (60-70%), eosinophils make up 1-3%, and monocytes account for 2-8%. This rarity makes basophils easily identifiable in blood smears.

These terminal components form a complex which inserts into the membrane to form a transmembrane ion channel which leads to lysis of the cell.

C5a is a powerful chemotactic agent and also an anaphylatoxin.

Activation of mast cells releases chemotactic factors for neutrophils and also vasoactive mediators such as histamine.

The alpha chain is specific for each VLA molecule (for example, VLA-1 is an alpha1beta1 molecule whilst VLA-6 is an alpha6beta1 molecule).

The high-walled endothelium of the post-capillary venules (HEV) in lymph nodes express vascular addressins, which are recognised by homing receptors on lymphocytes passing through the afferent lymphatics and which mediate entry of the lymphocytes into the lymph nodes.

Nearly all gamma delta T-cells in the skin express V gamma 5.

Blood group O (specifically O negative) is called the universal donor because it lacks A and B antigens on red blood cells, allowing it to be transfused to recipients of any blood group in emergencies. AB positive is the universal recipient, while A and B can only donate to their own types and AB.

G cells in the gastric mucosa are correctly matched with gastrin secretion. The other pairings are incorrect: B cells secrete insulin (in pancreas, not somatostatin), D cells secrete somatostatin (not insulin), and somatostatin is actually produced by delta cells in the pancreas and D cells in the stomach.

Langerhans Cell Histiocytosis (LCH) is characterized by proliferation of Langerhans cells which express CD1a as a specific surface marker. CD1a is considered the most specific immunohistochemical marker for LCH. CD57 is found on NK cells, CD3 on T-cells, and CD68 on macrophages/monocytes.

Langerhans Cell Histiocytosis (LCH) is characterized by proliferation of Langerhans cells, which are dendritic cells that normally reside in skin and lymph nodes. These cells pathologically express CD1a, which is a specific immunohistochemical marker for LCH diagnosis. CD57 is typically associated with NK cells, CD3 with T-cells, and CD68 with macrophages.

Cryoprecipitate is a blood product containing Factor VIII, von Willebrand factor, fibrinogen, and Factor XIII. It is prepared by thawing fresh frozen plasma and collecting the precipitate. Factor IX is NOT present in cryoprecipitate - it's found in fresh frozen plasma and prothrombin complex concentrates, which is why hemophilia B cannot be treated with cryoprecipitate.

In chronic hepatitis B, HBsAg and HBeAg are present, but anti-HBs is absent. IgM anti-HBc indicates acute infection; in chronic infection, only IgG anti-HBc is present, while IgM is typically negative.