BAFF and Autoimmune Disease
Samia Ragheb, Ph.D.
Wayne State University
Department of Neurology
Department of Immunology & Microbiology
MG is a B-cell Mediated Disease
1. AChR-specific antibodies are present in the serum of 85% of
all patients with generalized MG; these antibodies are
responsible for the pathology of MG, leading to impaired
neuromuscular transmission and subsequent muscle
weakness
2. In vitro, lymphocyte cultures from MG patients produce
AChR-specific antibodies
3. EAMG can be induced in lab animals; serum anti-AChR
antibodies are present in these animals
4. EAMG can be passively transferred, via antibodies, from
immune animals to naïve animals and from man to mouse
Overexpression of CXCL13,
CD23, and Bcl-2 in the
Myasthenic Thymus
CXCL13: promotes B-cell migration and homing of B-cells
to lymphoid follicles
CD23:
promotes the survival and differentiation of
germinal center B-cells through a mechanism that
involves upregulation of Bcl-2
Bcl-2:
pro-survival molecule that inhibits apoptosis
BAFF = TNFSF13b
Myeloid cells produce and secrete Baff (B-cell activating factor of
the tumor necrosis factor superfamily)
A membrane-bound form of Baff is also expressed on the surface
of myeloid cells; these include monocytes, macrophages, and
dendritic cells
Baff transgenic animals exhibit hypergammaglobulinemia,
lymphoproliferation, and B-cell hyperplasia; and they develop
autoimmune disease
In Baff deficient animals, there are defects in peripheral B-cell
maturation, and there are decreased levels of circulating
immunoglobulins
Serum BAFF Levels
Effect of Clinical Extent and Severity
on BAFF Levels
Class IV
Class III
Class II
Class I
0.0
0.5
1.0
1.5
2.0
2.5
Baff (ng/ml), mean ± SD
3.0
Effect of Presence or Absence of Serum
Anti-AChR Antibody on BAFF Levels
Receptors for BAFF
• Baff-R deficient mice lack marginal zone and follicular
B-cells
• TACI deficient mice have an increased number of
peripheral B-cells, they develop autoimmune disease, and
they exhibit fatal lymphoproliferation
The pro survival signals of Baff
are mediated by the Baff-R,
whereas the interaction of Baff
with TACI delivers inhibitory
signals
Immunofluorescent Staining of
Peripheral Blood Mononuclear Cells
•
•
•
•
CD3: mouse IgG1-FITC
CD20: mouse IgG2a-FITC
Baff-R: goat IgG anti human Baff-R + rabbit F(ab)’2 anti goat IgG-Cy5
TACI: biotinylated goat IgG anti human TACI + streptavidin-Cy5
Cell-Surface Expression of
BAFF-R and TACI
Thangarajh et al.:
• MG thymus with hyperplasia: macrophages express Baff
• Germinal center: B-cells express Baff-R
• Plasma levels of Baff were not different
• No differences in the percentages of BCMA, Baff-R, or TACIpositive B-cells
Li et al.:
• Increased percentage of CD19+ Baff-R+ B-cells
Kim et al.:
• Serum Baff levels are higher in MG patients
Myeloid Cells Produce and Secrete BAFF
Baff
Monocyte
Dendritic cell
B-cell
Immunofluorescent Staining of
Peripheral Blood Monocytes
• CD14: mouse IgM-FITC
• Baff: mouse IgG1 anti human Baff + goat F(ab)’2 anti mouse IgG-PE
BAFF Production by Adherent Monocytes
BAFF Production by
Adherent Monocytes
BAFF Production by THP-1 Cells
THP-1:
human acute monocytic leukemia
1 year old male
HLA: A2, A9, B5, DRw1, DRw2
BAFF Production by THP-1 Cells
Enrichment of Monocytes by
Immunomagnetic Separation
PBMC are treated
with a mixture of
mouse anti CD2,
CD7, CD16, CD19,
CD56, and CD235a
followed by anti
mouse IgG-coated
magnetic beads
BAFF Production by Monocytes
Dendritic Cell Lineages
Banchereau et al., 2000
Differentiation of Monocytes Into
Dendritic Cells
Maturation of Dendritic Cells With
sCD40L (CD154)
Cytokine Production by
Dendritic Cells
sCD40L
Immature DC
254.0 pg/ml
5.0
0
0
IL-4
IL-10
IL-12
IL-17
Mature DC
192.0 pg/ml
5.4
1.3
0
BAFF Production by Dendritic Cells
Ueno et al., 2007
Contributors
Basic Science
Clinical
Samia Ragheb, Ph.D.
Felicitas Gonzales, B.S.
Kirk Simon, B.S.
Yanfeng Li, M.S.
Robert Lisak, M.D.
Richard Lewis, M.D.
Gregory Van Stavern, M.D.
Wayne State University School of Medicine
Supported by the Muscular Dystrophy Association (MDA)