Discussion
Although HIV infection is associated with progressive cellular immune dysfunction，the mechanism of this dysfunction is poorly understood［16］.CD4+T-cells are depleted during the course of HIV disease，but less than 0.2%of these cells become infected with HIV［17］.Recently it has been shown that up to 25%of dendritic cells，the primary antigen presenting cells of the immune system，are infected with HIV［8-10］.Infection of these cells leads to dysfunction and loss of antigen presentation，which may be the most significant factor in the development of cellular immunodeficiency in AIDS［10］.Thus，a treatment modality that promotes normal antigen presentation in HIV disease is desirable.
DNCB exerts a significant immunomodulatory effect on antigen presenting cells in vitro and in vivo［1，4，11］.The effect of topically applied DNCB appears to be systemic in nature，with cellular immune responses appearing at distant sites following DNCB application［1，12，18］.Dendritic cells exposed to DNCB in vivo and in vitro stimulate CD8+T-cells and natural killer cells［1，20］.Expansion of these lymphocyte populations in response to DNCB may be extremely useful in vivo，since HIV suppressor cells may be activated as part of this response，and viral replication may thus be controlled［21，22］.A concern about DNCB use is that CD4+T-cells would also be activated，leading to increased viral infection of these cells（the so-called‘food for the virus’theory）with a fall in CD4+T-cell counts and propagation of the disease［23，24］.
Our pilot study of topical DNCB use in patients with early-stage HIV disease demonstrates that DNCB is safe in these patients.The local complication rate from application of the compound was 10%（2/20 subjects），and this type of complication was easily treated with local measures.Extensive allergic contact dermatitis has been reported with excessive DNCB application［25］，but this problem was not seen when DNCB was used according to the study protocol.Although each patient in our study experienced a‘reflare’（systemic response）with the DNCB regimen that was used，the optimum DNCB treatment dose in individual subjects has not been determined.
A significant finding of our study was that DNCB application did not result in depletion of CD4+T-cells.This observation appears to invalidate the‘food for the virus’theory of increased CD4+T-cell destruction due to DNCB.More important，DNCB sensitization was associated with a significant rise in CD8+T-cells and natural killer cells（see Table 2），presumably via dendritic cell modulation.Although the quantitative expansion of these lymphocyte populations persisted over time，the qualitative antiviral properties of these CD8+T-cell and natural killer subsets were not defined.Further study of HIV suppressor subsets in DNCB-treated patients is now in progress.(https://www.daowen.com)
DNCB application had a significant effect on viral replication，as shown by serum HIV RNA levels（see Table 3）.These levels decreased with chronic DNCB use，while they appeared to increase in patients who discontinued DNCB.Patients with higher viral loads（＞10，000 copies/ml）had a greater response to DNCB，while patients with lower amounts of circulating HIV RNA（＜10，000 copies/ml）maintained these levels over time（see Table 3）.These results are consistent with the expansion of CD8+T-cell and natural killer cell subsets that may control viral replication in response to DNCB.
In summary，topical DNCB application appears to be safe in patients with early HIV disease.Use of DNCB does not cause CD4+T-cell depletion，and it is associated with an increase in CD8+T-cells and natural killer cells.This effect is accompanied by a decrease in viral replication，as measured by serum HIV RNA levels.The results of this pilot study require confirmation in larger controlled clinical trials，and the effect of DNCB on HIV suppressor cells merits further evaluation.Testing of this inexpensive，readily available compound in patients with more advanced HIV disease，as well as in seronegative atrisk subjects［26］，is also warranted.
