Indian Journal of Dermatology, Venereology and Leprology Medknow Publications on behalf of The Indian Association of Dermatologists, Venereologists and Leprologists (IADVL) ISSN: 0378-6323 EISSN: 0973-3922 Vol. 75, Num. 5, 2009, pp. 514-514

Indian Journal of Dermatology, Venereology and Leprology, Vol. 75, No. 5, September-October, 2009, pp. 514

Letter to the Editor

Authors' reply

Mohan Kudur, C. Balachandran, S. D. Shenoi, Ragavendra Rao, H. Sripathi, Smitha Prabhu

Department of Skin and STD, Kasturba Medical College, Manipal, India

Correspondence Address: Dr. Mohan Kudur, Department of Skin and STD, Kasturba Medical College, Manipal-576 104, Udupi Dist, Karnataka, India
mohankudur@rediffmail.com

Code Number: dv09165

DOI: 10.4103/0378-6323.55403

Sir,

We appreciate your ^[1] interest in our letter. ^[2] We know, beyond doubt, that dinitrochlorobenzene (DNCB) has shown mutagenicity in the Ames test with the salmonella typhimurium plate assay. ^[3] The Ames test is used to test a chemical / drug for mutagenicity, and is named after its developer, Bruce Ames. ^[4]

The use of the Ames test is based on the assumption that any substance that is mutagenic (for the bacteria used in this test) may also turn out to be a carcinogen. Although, in fact, some substances that cause cancer in laboratory animals (Dioxin, for example) do not give a positive Ames test (and vice-versa).

However, drugs like norfloxacin, Isoniazid, and PUVA (psoralen), textile dyes, and fumes of oils have also been found to be mutagenic by the Ames test. Nevertheless, these drugs and chemicals are widely used world wide. The most potent mutagenic agent in the early trials of the Ames test is parsnip juice. DNCB was found to be noncarcinogenic when fed in large doses to rats, mice, guinea pigs, and man. ^[5]

The immunomodulatory effects of topical DNCB are well known and can be used in patients with HIV, ^[6] verruca vulgaris, verruca plana and recurrent warts, ^[7],[8] and nodular prurigo. ^[9] DNCB therapy is being used in HIV patients for the last 10 years, and the only reported toxicity has been localized dermatitis at the application site. ^[6]

On account of unknown etiology and an unpredictable course, treatment of alopecia areata is palliative. Topical immunotherapy by contact sensitizers is an effective and accepted therapeutic modality in the treatment of chronic severe alopecia areata. Treatment with dinitrochlorobenzene is cost-effective, its response rate varies from 60 - 80%, it is easy to apply, and is painless, with easily tolerable side effects. However, both DPCP (Diphenyl cyclopropenone) and SADBE (squaric acid dibutyl ester) are expensive. ^[10]

To conclude, DNCB remains a useful contact sensitizer in alopecia areata and warts.

References

1.	Singh G, Lavanya MS. Topical immunotherapy with DNCB: Safety concerns. Indian J Dermatol Venereol Leprol 2009;75:513-4.  Back to cited text no. 1  [PUBMED]
2.	Mohan KH, Balachandran C, Shenoi SD, Rao R, Sripathi H, Prabhu S. Topical initrochlorobenzene (DNCB) for alopecia areata: Revisited. Indian J Dermatol Venereol Leprol 2008;74:401-2.  Back to cited text no. 2  [PUBMED]
3.	Black HS, Castrow FF 2nd, Gerguis J. The mutagenicity of dinitrochlorobenzene. Arch Dermatol 1985;121:348-9.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]
4.	Ames BN, Mccann J, Yamasaki E. Methods for detecting carcinogens and mutagens with the Salmonella/mammalian-microsome mutagenicity test. Mutat Res 1975;31:347-64.  Back to cited text no. 4  [PUBMED]
5.	Stricker RB, Elswood BF. Dendritic cells and dinitrochlorobenzene (DNCB): A new treatment approach to AIDS. Immunol Lett 1991;29:191-6.  Back to cited text no. 5  [PUBMED]
6.	Stricker RB, Elswood BF. Topical dinitrochlorobenzene in HIV disease. J Am Acad Dermatol 1993;28:796-7.  Back to cited text no. 6  [PUBMED]
7.	Johansson E, Forstrom L. Dinitrochlorbenzene (DNCB) treatment of viral warts: A 5-year follow-up study. Acta Derm Venereol 1984;64:529-33.   Back to cited text no. 7
8.	Buckner D, Price NM. Immunotherapy of verrucae vulgaris with dinitrochlorobenzene. Br J Dermatol 1978;98:451-5.  Back to cited text no. 8  [PUBMED]
9.	Yoshizawa Y, Kitamura K, Maibach HI. Successful immunotherapy of chronic nodular prurigo with topical dinitrochlorobenzene. Br J Dermatol 1999;141:387-9.  Back to cited text no. 9  [PUBMED]  [FULLTEXT]
10.	Rokhsar CK, Shupack JL, Vafai JJ, Washenik K. Efficacy of topical sensitizers in the treatment of alopecia areata. J Am Acad Dermatol 1998;39:751-61.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]

Copyright 2009 - Indian Journal of Dermatology, Venereology and Leprology