Distribution of a contact sensitizer, 1-fluoro-2,4-dinitro-benzene, in the the tissues of the guinea-pig.

The distribution of tritiated 1-fluoro-2,4-dinitrobenzene (DNFBT) in the tissues was investigated after topical application to, or injection in, the skin of the guinea-pig. The elimination of the chemical from guinea-pig skin was compared with the removal of intradermally injected radio-iodinated bovine serum albumin (BSA-I) in the guinea-pig, rat and rabbit. The protein was rapidly eliminated from the relatively thin pretibial skin though it was retained for longer periods in dorsal skin; small amounts (≤2 per cent of the dose) were retained in the lymph nodes, spleen or contralateral pretibial skin. Comparatively more DNFBT than BSA-I remained in treated skin. The retention of the chemical was more marked in the skin of sensitized than unsensitized guinea-pigs, unless a toxic concentration of DNFBT (1.0 per cent) was applied. Approximately half of the chemical retained after application to dorsal skin was extractable with alcohol—acetone; 6–12 per cent of the extracted DNFBT was unbound. After topical application to pretibial skin approximately one-third of the dose was retained in the liver, 5 per cent in lymph nodes and 3 per cent in circulating leucocytes—21 per cent was excreted on the first day. The presence of unbound DNFBT in treated skin and of radioactive leucocytes in blood suggested that lymphocytes could be dinitrophenylated .