Immunohistochemical study of lymphoid tissue in human fetal salivary gland.

Immunoreactivity of lysozyme (LY), lactoferrin (LF), alpha 1-antichymotrypsin (alpha 1-ACT), alpha 1-antitrypsin (alpha 1-AT), keratin proteins KL1, PKK1, K8.12, S-100 protein, MAM-3, MAM-6, and epithelial membrane antigen (EMA) were evaluated in lymphoid and glandular tissues of developing salivary gland of human fetus (gestational age ranging from 17 to 40 wk to investigate the role of lymphoid tissue in developing salivary glands. In a total of 79 cases, lymphoid cell aggregations were noted in parotid (57 cases), submandibular (21 cases) and sublingual (5 cases) glands. Mononuclear cells showing intense activity of LY, alpha 1-ACT and alpha 1-AT were present in the lymphoid aggregation. The glandular ducts embedded in lymphoid tissue were negative to MAM-3, MAM-6, EMA and S-100 protein, but showed positive PKK1 and KL1 reaction during early stages of development, and showed degeneration and effacement upon increase in number and LY activity of the mononuclear cells. The lymphoid aggregations progressively emerged as lymph nodes.