Untitled - D Ank Unlimited

light zone 453 linkage disequilibrium
Side Scatter
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0
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Forward Light Scatter
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Neutrophils
Monocytes
Lymphocytes
Each dot represents data from one cell. The bigger the cell, the larger the
FSC signal and the farther to the right the dot will appear on the x-axis.
The more complex or granular the cell, the larger the SCC signal and the
higher it will appear on the y-axis. It is possible to discern lymphocytes,
monocytes, and neutrophils in this plot.
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0
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FITC
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Wavelength (nm)
650
700
The absorption and emission spectra for the FITC fluorochrome are
shown. The peak absorption is around 488 nm and the peak emission is
around 530 nm.
CD 19 PE
10 4
10 3
10 2
10 1
10 0
10 0
10 1
10 2
CD3 FITC
FITC-positive cells fall in the lower right quadrant and PE-positive cells
fall in the upper left quadrant. Cells that are positive for both FITC and
PE are in the upper right quadrant.
flow stream yields data on cell granularity or fine structure.
Light scatter depends on such factors as cell size and shape,
cell orientation in flow, cellular internal structure, laser beam
shape and wavelength, and angle of light collection.
light zone
A region of a germinal center in secondary lymphoid tissue
containing centrocytes that do not divide but interact with
10 3
10 4
follicular dendritic cells. A site of isotype switching where
B cells in which immunoglobulin genes have undergone
somatic hypermutation are negatively selected to facilitate
peripheral B cell tolerance or selected for affinity maturation,
i.e., increased affinity for antigen.
limiting dilution
A method of preparing aliquots that contain single cells
through dilution to a point where each aliquot contains only
one cell. The apportionment of cells by this method follows
the Poissonian distribution that yields 37% of aliquots without
cells and 63% with one or more cells. This technique
may be used to estimate the frequency of a certain cell in
a population. For example, it may be employed to approximate
the frequency of helper T lymphocytes, cytotoxic T
lymphocytes, or B lymphocytes in a lymphoid cell suspension
or to isolate cells for cloning in the production of
monoclonal antibodies.
lineage infidelity
Cells that undergo neoplastic transformation may express
molecules on their surfaces that are alien to their lineage.
linear determinant
Antigenic determinant produced by adjacent amino acid
residues in the covalent sequence in proteins. Linear determinants
of six amino acids interact with specific antibodies.
Occasionally, they may appear on the surface of a native
folded protein, but they are more commonly unavailable
in the native configuration and become available only for
interaction with antibody upon denaturation of the protein.
linear epitope
Antigenic determinant of a protein molecule recognized
by an antibody that consists of a linear sequence of amino
acids within the protein’s primary structure.
linear staining
The interaction of IgG and possibly C3 on peripheral capillary
loops of renal glomeruli in antiglomerular basement
membrane diseases such as Goodpasture’s syndrome.
The use of fluorescein-labeled goat or rabbit antiimmunoglobulin
preparations permits this smooth, thin, delicate,
ribbon-like staining pattern to be recognized by immunofluorescence
microscopy. This pattern is in sharp contrast to
the lumpy, bumpy patterns of immunofluorescence staining
seen in immune complex diseases.
linkage analysis
The use of simple tandem repeat sequences or microsatellites
to screen an entire genome for linkage with a trait and
identify non-MHC loci linked with disease.
linkage disequilibrium
The appearance of human leukocyte antigen (HLA) genes
on the same chromosome with greater frequency than
would be expected by chance. This has been demonstrated
by detailed studies of populations and families, employing
outbred groups in which numerous different haplotypes
are present. With respect to the HLA-A, -B, and -C loci,
a possible explanation for linkage disequilibrium is that
the genes have not had sufficient time to reach equilibrium;
however, this possibility is remote for HLA-A, -B,
and -D linkage disequilibrium. Natural selection has
been suggested to maintain linkage disequilibrium that is
advantageous. If products of two histocompatibility loci
play a role in the immune response and appear on the same
chromosome, they may reinforce one another and represent
an advantageous association. An example of linkage
L