Cryostat sections of epididymides from mice were stained with monoclonal antibodies against immuno-competent cells. This investigation was undertaken to gain basic data about the distribution of macrophages. T lymphocytes, MHC class II and MIF in the normal murine epididymis to establish the mouse as a model for immunological epididymal research. The most important findings were as follows. (1) Macrophages, T lymphocytes, MHC class II and MIF positive cells were distributed similarly in the caput, corpus and cauda epididymis. (2) Macrophages were the most frequent leucocytes and the majority were located in the peritubular layer. (3) The MHC class II determinant was also expressed mostly in the peritubular layer and interstitium. These cells were similar in appearance and location to macrophages. (4) Significantly fewer T lymphocytes were found and their main location was the interstitium. T-helper and T-suppressor/cytotoxic lymphocytes did not differ significantly in their regional or histological distribution patterns. (5) The ratio of T-helper to T-suppressor/cytotoxic lymphocytes was 1:1. (6) MIF was detected almost exclusively in blood vessels and the surrounding connective tissue. (7) No invasion of leucocytes into the epididymal lumen was observed. It is concluded that macrophages seem to be the most important immunological cell type in the murine epididymis.

A monoclonal antibody (BM8) raised in the rat against cultured mouse bone marrow-derived macrophages reacted only with macrophages and not with granulocytes, mast cells, platelets, lymphocytes, fibroblasts, and endothelial cells. BM8 did not detect blood monocytes. In cultured bone-marrow cells, expression of BM8-antigen was found on a few macrophages after one day of culture and reached its maximum level with 80% positive macrophages after 7-10 days of culture. The antibody BM8 belonged to the IgG2a subclass, was non-cytotoxic and directed against a 125 kD membrane antigen. In cryostat sections of normal mouse tissues (spleen, lymph node, thymus, liver, skin) BM8 detected tissue-fixed macrophages and Langerhans cells in the skin. In spleen and lymph node, BM8 reacted with macrophages in the red pulp and in the medullary cords, respectively, but not with heavily phagocytosing marginal-zone macrophages, as revealed by in-vivo phagocytosis of colloidal carbon. In granulomata induced by complete Freund's adjuvant, BM8 detected inflammatory macrophages but not epithelioid cells. Thus, antibody BM8 detected a differentiation antigen expressed only on mature, tissue-fixed macrophages.

No abstract

Two strains of mice, BALB/c and C57B1/6, which are known to differ in their inflammatory responsiveness to allergens, were analyzed regarding their expression of macrophage migration inhibitory factor (MIF). Allergic contact dermatitis to 2,4-dinitro-1-fluorobenzene and irritant contact dermatitis to croton oil were studied immunohistologically at designated time intervals after elicitation. BALB/c mice presented a significantly more intense ear swelling response than C57B1/6 mice and showed a strong endothelial MIF expression in the early phase of inflammation in both allergic and irritant contact dermatitis. Endothelial MIF expression was much weaker in C57B1/6 mice. Furthermore, the infiltration rate of inflammatory cells (MIF+ and BM8+ macrophages, Lyt2+ and L3T4+ T cells) was significantly higher in BALB/c than in C57B1/6 mice. We conclude that genetically determined differences of susceptibility to allergens and irritants in BALB/c and C57B1/6 mice are reflected by the intensity of MIF expression in the microvascular endothelium and immigrating inflammatory cells. MIF seems to appear as first molecular equivalent of developing inflammation and probably determines the degree of cellular infiltration.