ABSTRACTS – ORAL PRESENTATIONS - AMCA, spol. s r.o.

P66. IMPAIRED EXPRESSION OF CD154 IN THE CD4+ T CELLS IN CVID PATIENTS IN
RESPONSE TO DIFFERENT STIMULI
Olga Ticha, Marcela Vlkova
Department of Clinical Immunology and Allergology, Faculty of Medicine, Masaryk
University and St Anne’s University Hospital, Brno, Czech Republic; olga.ticha@fnusa.cz
Patients with common variable deficiency (CVID) is heterogeneous group of disorders
characteristic with impairment in specific antibody production and decreased levels
of some or all immunoglobulin isotypes in serum. Underlying genetic defects are not
yet well defined. Apart from defects in B-cell function one of possible mechanisms
could be failure in T cell - B cell activation and interaction. The basic for production of
immunoglobulin is interaction between costimulatory molecule CD154 (CD40L) on the
CD4+ T cells and molecule CD40 on the B cells. CD40L is expressed on the surface of
helper T cells after activation by antigen and costimulators. CD40L on the activated T
helper cell then binds to CD40 on antigen activated B cells and initiates B cell proliferation
and differentiation and production of immunoglobulins.
We studied expression levels of molecules CD69 and CD154 (CD40L) on surface of
CD3+8- lymphocytes of CVID patients in response to stimulation with ionomycine (IM)
and phorbol myristate acetate (PMA) and on surface of CD3+4+ lymphocytes in response
to stimulation with anti-CD3 and anti-CD28 monoclonal antibodies in CVID patients
compare to group of healthy controls. Isolated peripheral blood mononuclear cells were
used in our experiment.
After 4 hour stimulation with IM and PMA the percentage of CD3+CD8- lymphocytes
which expressed costimulatory molecule CD154 on their surface was comparable in
both groups. But statistically significant difference in percentage of activated CD3+8-
lymphocytes expressing CD69 in both groups was found.
On the contrary CVID patients in our cohort show statistically significant decrease in
level of activation of CD3+CD4+ lymphocytes and decreased percentage of CD3+8+
expressing costimulatory molecule CD154 on their surface after stimulation with anti-
CD3 together with anti–CD28 monoclonal antibody after 24 hours.
We identified group of patients with low percentage of CD3+4+ lymphocytes expressing
molecule CD154 (< 20% from CD3+4+) after anti-CD3 and anti-CD28 antibodies which
are divided in to two different subgroups based on expression of CD154 after stimulation
with IM and PMA - with normal or decreased levels compare to controls although all of
them have decreased percentage of CD3+8-CD69+ lymphocytes. It is possible that this
is caused by different underlying defect in signaling in the upper levels of activation
pathway.
Through the fact that defect of molecule CD154 is not described as a fundamental
underlying cause for impaired antibody production in CVID patients our results confirm
previously published findings showing that for some patients decreased expression
or activation of this molecule after stimulation could be crucial. We denoted concrete
patients whose molecules in activation signaling pathways should be studied closely for
phosphorylation and expression levels.
Analytical Cytometry VII 167