BSCI 2201L Lecture Notes - Lecture 11: Natural Killer Cell, Blood Film, Adaptive Immune System

10 views6 pages
Musbah Shaheen
BSCI 202.2
Due 4/9/2015
Lab Report 11
Hematopoiesis and Blood Cells
Abstract:
Hematopoiesis is the process by which all the blood cells are formed. Blood is a fluid
tissue containing cells that are essential for delivering nutrients to body cells and for immune
responses. In this experiment we studies blood smears in order to identify different types of
blood cell. We also studies the absorbance spectrum of hemoglobin, the oxygen carrying
molecule in erythrocytes.
Introduction:
Hematopoiesis refers to the differentiation of blood cell types from pluripotent stem
cells. In bone marrow, multipotential hematopoietic stem cells (hemocytoblasts) differentiate
into a common myeloid progenitors (CMP) and common lymphoid progenitors (CLP). CMPs give
rise to red blood cells (erythrocytes), megakaryocytes that give rise to blood platelets, and a
variety of phagocytic cells involved in the innate immune system. These include basophil,
neutrophil, eosinophil and monocytes. CLPs differentiate into natural killer cells and small
lymphocytes. These lymphocytes differentiate into T lymphocytes and B lymphocytes which are
responsible for the adaptive immune system. B lymphocytes differentiate into antibody-forming
plasma cells.
Red blood cells (erythrocytes) are small, concave and contain hemoglobin. Hemoglobin
is the oxygen carrying molecule in the blood. Human hemoglobin consists of two alpha subunits
and two beta subunits, each has a porphyrin ring with iron Fe+2 which binds a single oxygen
molecule. Mast cells and basophils respond to antigens by producing histamines and interleukin
which recruit other immune cells to the inflammation site. They also release complement
factors that act as antimicrobial peptides. Eosinophils release cytotoxins and can activate other
immune cells like T-cells and mast cells. Platelets are crucial for blood clotting. They release
thromboplastin which converts prothrombin to thrombin. Thrombin converts soluble fibrinogen
into fibrin which forms a mesh network that captures red blood cells to form a blood clot.
The adaptive immune response includes B cells which can recognize foreign antigens
and release antibodies specific for that antigen. T cells are also part of the adaptive immune
response. They include CD8 (killer cells) which recognize antigens on the surface of infected cells
and destroy them using cytotoxins, and CD4 (helper cells) which bind to B cells causing them to
divide and recruit phagocytes via lymphokines.
In this lab session, we used a blood smear to identify different types of blood cells under
the microscope. We also plotted the hemoglobin absorbance spectrum.
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Materials and Methods:
In order to view blood cells under the microscope, we created a blood smear by using
5ul of human blood on a glass slide and then using another slide to create a thin blood layer
containing a single layer of blood cells. We then fixed the smear using methanol and Wright’s
stain for 2 minutes. The smear was then studied under the microscope.
In order to enhance the collection of WBS images, we used the HetaSep method which
serves to separate the components of the blood into three layers: plasma, red blood cells and
white blood cells. The WBC layer was then stained with methylene blue and viewed under the
microscope.
Finally, In order to study the absorbance spectrum for hemoglobin, we used two
samples. The first sample contained whole blood which red blood cells were hemolyzed with
detergent. The second sample contained purified hemoglobin. The absorbance of hemoglobin
and hemolyzed blood were measured using a spectrophotometer from 450-700 nm in 10 nm
increments.
Results and Conclusion
Fig.1 Red Blood Cells under bright field 40X. The cells are de-nucleated and are thinner in the
center due to their concave shape.
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