Introduction
Infertility is defined as the failure to conceive after one year of
unprotected intercourse. Approximately 7%–15% of couples of
reproductive age suffer from infertility. Many factors, including
endocrine and immunological factors, might predispose a couple to
infertility [1]. Unexplained infertility (UEI) is a frustrating
state for the subfertile couple with unknown causes. UEI is a diagnosis
of exclusion when the necessary infertility workup is found to be normal
[2]. Involvement of the immune system in unexplained infertility has
been found [1].
It is known that the induction of immunologic tolerance in the decidua
is vital to accept fetal alloantigens. Cytokines play an important role
in establishing and maintenance of such tolerance. Th1 cytokines (like
IFN-γ, IL-2, and TNF) cause pregnancy failure, whereas Th2 cytokines
(like IL-4, IL-5 and IL-10, which suppress Th1 responses) cause the
tolerance to the fetus and pregnancy. Imbalance of the cytokine network
can lead to impaired pregnancy and infertility, including unexplained
infertility [3].
Published studies highlighted that reduced fertility might be associated
with the dysregulation of immune system reactions resulting in
autoimmunity [4, 5]. One of the most common autoimmune diseases that
affect females in the reproductive age is Hashimoto thyroiditis [6].
Hashimoto’s thyroiditis (HT) is an autoimmune thyroid disease
characterized by follicular lymphocytic infiltration in the thyroid
gland with the formation of germinal centres, atrophy of the follicular
epithelial cells, Hurthle cell change, and gradual fibrous replacement
of the thyroid parenchyma [7]. Disturbed balance of pro- and
anti-inflammatory cytokines are thought to play an essential role in the
pathogenesis of autoimmune thyroid diseases. Correlation between a high
level of Interferon (IFN)- γ and autoimmune thyroiditis has been widely
established [8].
Therefore, we aimed to evaluate serum IFN- γ level and the level of
expression of IFN- γ gene in Egyptian women with HT and their possible
associations with UEI. Accordingly, we can use IFN- γ level and the
level of expression of IFN- γ gene as an Immunological marker for UEI in
female patients suffering from HT.