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Lymphocytes:
Lymphocytes are produced by the primary lymphoid organs
(bone marrow, thymus, bursa of Fabricius(birds)) and migrate through the
circulation to the secondary lymphoid tissues such as spleen and lymph
nodes. Unlike neutrophils, lymphocytes have relatively long lives and
circulate among and between various lymphoid tissues via the blood and
lymphatics.
In general, lymphocytes are small cells with densely staining
nuclei and minimal amounts of cytoplasm. Plasma cells are larger cells
with more abundant basophilic cytoplasm and with a prominent perinuclear
clearing associated with the golgi apparatus. Russell body cells are large
with a cytoplasm stuffed full of eosinophilic material.
Two basic classes:
B-cells are the antibody producing cells. They are capable
of producing antibody to a specific antigen provided they receive T-cell
help. B-cells mature into the antibody producing plasma cells. Aged plasma
cells become "constipated" and are seen in tissue sections as
characteristic "Russell bodies".
T-cells are further subdivided into helper T cells and cytotoxic
T cells. Helper T cells provide help to B cells for antibody production.
Cytotoxic T cells are capable of recognizing and then killing cells expressing
abnormal antigens on their surface (e.g. virus infected cells and certain
tumour cells)
This is a very simplistic explanation of lymphocytes. There
are many other subdivisions and classes of lymphocytes, a discussion of
which is beyond the scope of this exercise.
 
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