The studies were conducted in order to investigate the cell density and cytological feature of epidermal Langerhans cells in the normal and hypersensitized Guinea pigs. The degree of hypersensitivity was assayed by measuring´ the increment of ear thickness. Contact hypersensitivity in albino Guinea pigs was induced by daily painting with 1% DNFB(2, 4-dinitro-1-fluorobenzene) for seven consecutive days, and challenging the ear with 0. 3% D\TFB.
Punch biopsies were performed in the skin of normal and hypersensitized Guinea pigs. Epidermal sheets 5.vere obtained from those skin samples using EDTA as a separation medium, and incubate to demonstrate ATPase activity in ATP-Pb´ substrate.
Some specimens were also processed for electron microscopy.
The results observed under light and electron microscopes were summarized as follows:
1. ATPase-positive Langerhans cells were found in specimens from the ear, abdomen, back and foot
pad of normal Guinea pigs with mean values of 1107, 1125, 1113 and 1067/mm2, respectively.
2. Ear swelling was maximum at 24 to 48 hours after DNFB challenge with a characteristic histological
feature of leukocytes infiltration.
3. Density of ATPase-positive Langerhans cells in the hypersensitized Guinea pigs began to decrease at 6 hours, and was minimal at 24 to 48 hours after D--vTFB challenge. Abnormal cellular configurations were also seen during this period.
4. Within; 96 hours after DNFB challenge, most Langerhans cells resumed their typical dendritic shape and cell density returned to normal.
In electron microscopy of hypersensitized Guinea pigs, epiderml Langerhans cells showed cytoplasmic swelling, dilatation of perinuclear cisterna, vacuolar degeneration and disorganization of cytoplasmic organells
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