The influence of copper, selenium and zinc on the response to the Montenegro skin test in subjects vaccinated against American cutaneous leishmaniasis

We evaluated the relationship between the trace elements copper, zinc and selenium and the response to the Montenegro skin test (MST) in 172 volunteers vaccinated against American cutaneous leishmaniasis. The MST diameter was categorized as negative and in quartiles of positive response, constituting five groups. Trace element serum levels were analyzed by coupled plasma atomic emission spectrometry and hydride generation atomic absorption spectrometry, with study subjects classified into two groups depending on low or high levels of trace elements observed. MST-positive subjects had an MST diameter (mean ± SD) of 10.35 ± 4.64 mm, with copper, selenium and zinc serum levels of 1433.7 ± 665.7 μg/l, 88.6 ± 39 μg/l and 999.2 ± 366 μg/l, respectively. The MST diameter was significantly different in the selenium groups only. The selenium levels also differed with the quartiles of the MST diameters of individuals testing positive (P < 0.05). Our findings suggest that trace elements, particularly selenium, should be measured in future vaccine trials so that vaccine immunogenicity and response can be assessed and compared between different studies.