Testicular Macrophages: Isolation, Characterization and Hormonal Responsiveness

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Abstract
Macrophages were isolated from rat testes with trypsin treatment and established in culture using a differential attachment technique. The cells were maintained in culture in Medium 199 at 32.degree. C. The cells were then characterized for their ability to express traditional immunological function as well as to secrete lactate under the regulation of various hormones. Viable cultures of macrophages evidently were obtained since: the cells stained intensely for nonspecific esterase; they possessed Fc receptors on their cytoplasmic membranes; they were capable of phagocytosing 3H-labeled Escherichia coli and carbon particles; and they were highly resistant to the effects of trypsin to induce detachment from the culture substrate. These cultures were not contaminated with Leydig cells or Sertoli cells since they were negative for 3.beta.-hydroxy-steroid dehydrogenase and did not secrete androgen-binding protein (ABP). These cells were capable of responding to FSH in a dose-dependent manner by increasing the secretion of lactate. Maximal stimulation was observed with 1 .mu.g FSH/ml which resulted in a 2.5-fold increase over control values. Dibutyryl cAMP (dbcAMP) also caused a dose-related increase in lactate production by these cells. Luteinizing hormone, insulin, testosterone or 17.beta.-estradiol had no similar effect on lactate production by these cells. Peritoneal macrophages were not responsive to FSH or dbcAMP. A highly enriched population of testicular macrophages apparently can be maintained in culture and express several immunological characteristics traditionally ascribed to macrophages. These cells were capable of responding to FSH in a specific manner.