Index
After many years of looking through a microscope at human blood slides, a hematologist in a hospital laboratory is very excited that he found five different types of leukocytes (white blood cells) in a row. The hematologist gives you the following hints so that you can identify the white cells:
The logic puzzle can be solved by letting the letters N, M, B, L, and E represent the neutrophil, monocyte, basophil, lymphocyte, and eosinophil, respectively. From Clue 1 we know that L is to the right of B; this is the sequence BL. Clue 2 tells us that NM is another sequence. Clue 3 only allows the sequences LE and EL, but EL is not possible because of Clue 1. Combining BL and LE, we now have the sequences BLE and NM. From Clue 3 we know that E is not adjacent to N, therefore the sequence of the lymphocytes is NMBLE.
The white cells are: 1) neutrophil, 2) monocyte, 3) basophil, 4) lymphocyte, 5) eosinophil. The background shows some erythrocytes (red blood cells) which have no nucleus.
Microscopic blood analysis can be very useful for identifying or diagnosing many types of diseases such as anemia, malaria, syphilis, heavy metal poisoning, leukemia, appendicitis, etc.
Leukocytes are the first line of defense of the immune system. Leukocytes are derived from bone marrow stem cells and have three main categories: Lymphocytes, Phagocytes, and Auxiliary Cells.
Lymphocytes
There are two types of lymphocytes: T-Cells and B-cells. T-cells develop in the thymus, a
lymphatic organ in the chest behind the breastbone, whereas B-cells develop in the adult
bone marrow. T-cells produce cytokine proteins which are interpreted by phagocytes as commands to
destroy the material that they have taken up.
B-cells produce antibodies that help phagocytes to recognize foreign material.
Phagocytes
Named from the Greek word "phagein" (to eat),
phagocytes are cells that engulf foreign particles, including infectious agents, such as bacteria.
Monocytes, neutrophils, and eosinophils are the main phagocytic cells. They search and
embrace foreign particles, and then destroy them.
Auxiliary cells
Basophils, along with mast cells and platelets, secrete inflammatory mediators
which attract leukocytes to the point of infection.
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| Red blood cells infected with malaria parasite |
Malaria is caused by the protozoan parasites of the genus Plasmodium which are transmitted by the bite of an infected Anopheles mosquito. Malaria parasites evade the body's immune system defenses by reproducing inside of the red blood cells. In this way, they avoid being detected and destroyed by the white blood cells.
