A role for acidophilic granulocytes in the testis of the gilthead seabream (Sparus aurata L., Teleostei)

Abstract

In mammals, a complex interaction between the immune and the reproductive systems has been described, in which testicular immune cells produce cytokines and growth factors which modulate gonad functions, while specific gonad cells influence the immune response in this organ. In this study we describe the presence of acidophilic granulocytes in the testis of the hermaphrodite teleost fish gilthead seabream (Sparus aurata L.) by using a specific monoclonal antibody. During the post-spawning stage of the testis, this cell type appears in the germinal compartment, accumulates interleukin (IL)-1 and does not seem to be involved in the phagocytosis of degenerating cells. Moreover, in vitro, 11-ketotestosterone and 17 -oestradiol, the principal fish sexual steroids, regulate the respiratory burst activity of acidophilic granulocytes obtained from the head-kidney (the bone marrow equivalent in fish) and the intracellular accumulation of IL-1 by these cells. It is likely, therefore, that IL-1 produced by testicular acidophilic granulocytes regulates important functions of the testis in fish.

Professional phagocytic granulocytes of the bony fish gilthead seabream display functional adaptation to testicular microenvironment

“…The gonadosomatic index (GSI) was calculated as 100 ϫ (Wg/Wf), where Wg is the gonad weight, and Wf is the body weight. Gonads and head-kidneys were dissociated as described elsewhere [8,13]. Some gonads were processed by light microscopy and immunostained with a monoclonal antibody (mAb) specific to sbNLCs (G7) [6], as described [8].…”

“…In addition, sexual hormones influence the production of ROIs and IL-1␤ by head-kidney sbNLCs in vitro [8]. These results, together with the fact that sbNLCs do not proliferate in the testis [8], suggest that they are recruited from the head-kidney and that testis-specific microenvironment factors might influence their activities. Here, we show that the phagocytic and ROI production capacities of testicular sbNLCs are suppressed dramatically.…”

“…Previous results have demonstrated that sbNLCs are present in the testis of the gilthead seabream [8], a seasonal breeding teleost that is an excellent model for studying the testicular regression process, which occurs in seasonal testicular involution and sex reversion. In contrast to sbNLCs from the headkidney, testicular sbNLCs constitutively produce interleukin-1␤ (IL-1␤), a potent growth factor for mammalian spermatogonia and Leydig cells [9 -11], rather than being involved in the phagocytosis of degenerative germ cells [8,12].…”

“…In contrast to sbNLCs from the headkidney, testicular sbNLCs constitutively produce interleukin-1␤ (IL-1␤), a potent growth factor for mammalian spermatogonia and Leydig cells [9 -11], rather than being involved in the phagocytosis of degenerative germ cells [8,12]. In addition, sexual hormones influence the production of ROIs and IL-1␤ by head-kidney sbNLCs in vitro [8].…”

“…In contrast to sbNLCs from the headkidney, testicular sbNLCs constitutively produce interleukin-1␤ (IL-1␤), a potent growth factor for mammalian spermatogonia and Leydig cells [9 -11], rather than being involved in the phagocytosis of degenerative germ cells [8,12]. In addition, sexual hormones influence the production of ROIs and IL-1␤ by head-kidney sbNLCs in vitro [8]. These results, together with the fact that sbNLCs do not proliferate in the testis [8], suggest that they are recruited from the head-kidney and that testis-specific microenvironment factors might influence their activities.…”