white blood cell types

• White blood cells (WBC): leukocytes
• • leukocytes are produced from hematopoietic stem cells
  • triggered in response to infection
• Granulocytes: contain cytoplasmic granules

  • Nuetrophils: phagocyte that defends against bacteria
• Neutrophils

  • Fine granules appear purple after staining (contains enzymes to digest bacteria)
  • Polymorphonuclear: multi-lobed nucleus (lobes connected by thin strands of chromatin)
  • Account for 54-62% of circulating WBC
• Eosinophil: defend against endoparasites (parasitic worms)

  Deep red granules after staining
• Basophils: defend against ectoparasites

  • deep blue granular after staining
  • release histamines for inflammation
  • release heparin to inhibit blood clotting
• Agranulocytes: absence of prominent granules
• Monocytes: change into macrophages and destroy bacteria by phagocytosis, also the largest WBC
• Lymphocytes: main WBC in lymph

  • Account for 25-35% of circulating WBC
  • some can live for years
  • Natural killer (NK) cell, destroys infected of cancerous cells and induce apoptosis in target cell
• T lymphocytes: cellular immune response, direct cell to cell action

  • Activated by antigen-presenting cell (APC)
  • APC destroys foreign invaders and presents the antigens on its surface
  • APC travels to lymph nodes to find lymphocytes with matching receptors
• Helper T Cell: activates T cells and B cells

  • release chemicals to stimulate WBC production
• Cytotoxic T cell

  • infected body cells present the foreign antigen on their surface
  • can also target cancer cells by recognizing mutated proteins displayed as antigens
  • Cytotoxic T cell recognized cells that display that particular antigen
  • punctures the infected cell, leading to apoptosis
  • ensures T cells destroy the right cell
• Memory T Cell

  • long-lived cells that patrol for future exposure to that antigen
  • proliferate directly into active cytotoxic T cells when that happens
• B lymphocytes: humoral immune response (circulating protection)

  1. Primed when encountering antigen
  2. Finally activated by active helper T cell, ensures humoral response is activated only when needed
  3. Plasma cell, secretes antibodies (immunoglobulins) into bloodstream, antibodies bind to specific antigens to target infection
• Memory B Cell: Long-lived cells that patrol for future exposure, proliferate into plasma cells