الفهرس 
Introduction and Aim of WorkOnly 14 pages are availabe for public view
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Abstract
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INTRODUCTION AND AIM OF WORK
Introduction
The capacity to respond to immunologic stimuli rests principally in cells of the lymphoid
system which include T-lymphocyte population that is human thymus-derived and responsible for
cell-mediated immunity. and B-lymphocyte population that is bone marrow-derived and concerned
in the synthesis of circulating antibodies ( Wig::ell er a!..
1972).
Analysis of immune responses involving distinctive cell types has been greatly facilitated by
development of technology for separating and purifying different lymphocyte populations (Schlossman
and Hudson.
1973).
Lymphocyte separation is useful in the analysis of an increased number. or of morphologically
abnormaL peripheral blood lympho cytes with the objective of determining whether a
malignant proliferation is present. Also. it helps in the analysis of bone marrow aspirates
or lymphocytes obtained from lymph node biopsies to supplement the c lassie histopathological
methods..-\ third function of lymphocyte separation includes evidence of some alteration in
immune
system in different acute and chronic diseases. In some diseases such as infectious
mononucleosis. the ob.jective of the studv. is to characterize
the cellular response to a known organism. In other infections such as leprosy. the objective
is to characterize the elements of an ineffective immune response. In diseases of unknown
etiology such as rheumatoid arthritis. systemic lupus erythematosus. and sarcoidosis. the
studies are primarily made with a view toward uncovering features of the abnormal
immune response that might lead to a better understanding of the nature of these diseases (Ross
and Winchester. 1980).
Human peripheral blood T-cells can be identified by their formation of rosettes with
sheep red blood cells (SRBCs) (E-rosettes: a phenomenon mediated by receptors on the
T-cells specific for the SRBCs). This property. under normal conditions. is not shared by
monocytes. granulocytes orB-lymphocytes. hence this method is a basis for separating T-cells from
other peripheral blood mononuclear cells (PBMCs) (Fro/and. 1972: Janda! et al .. 1972). Since
this method allows for the recovery of both the E-rosetted T-cells and the non-E-rosened
population. therefore it can be used for obtaining purified B-cells. provided that the
monocyte cellular component of the peripheral blood mononuclear cell fraction obtained
following Ficoll-hypaque densitv
gradient centrifugation. is eliminated or reduced prior to E-rosetting procedure (}onda/
eta/ .. 1972).
The observation has been made that dextran. at optimal concen trations. added to
lymphocyte-SRBC mixture can serve to enhance rosette formation. This may be in part due to a
reduction in the electric charges at the cell surface which in turn allows a better
cell to cell contact (Brown eta/.. 1975).
The nylon wool separation of B-lymphocytes is based on the empirical observation that
B-lymphocytes adhere preferentially to nylon wool from which they can be eluted, whereas
T-lymphocytes do not adhere to the wool (Eisen et al., 1972).
Aim of Work
This work is intended to evaluate three different. commonly used. methods for separation ofT-
and B-lymphocytes. These methods are E rosetting using Ficoll-hypaque. rosetting with
dextran and rosetting using nylon wool. The work aims at finding out the simplest.
most rapid. most reliable and cheapest technique for lymphocyte separation.