ReviewLevels of salivary IgA antibodies to Candida spp. in HIV-infected adult patients: A systematic review
Introduction
The main sequelae of HIV infection are frequent persistent opportunistic infections of mucosal surfaces,1, 2, 3 with oral candidiasis being the most common.2, 3, 4, 5, 6 This suggests that the oral mucosal defense mechanisms of these patients have been compromised. Saliva contains a variety of proteins that play a key role in maintaining oral defenses and protecting oral tissues.7 One of these proteins is salivary secretory immunoglobulin A (S-IgA), which affords protection by inhibiting microorganisms’ adhering to and penetrating mucosal tissues,8, 9 including Candida albicans,10, 11 an etiological agent of oral candidiasis.12
HIV-infected patients are generally colonized with Candida species (spp.),12 C. albicans being the most frequent species observed.12, 13, 14 Therefore, a decreased level of S-IgA would permit colonization and development of oral candidiasis. However, the role of specific antibody in protecting mucosal surfaces has not been elucidated.1 This is due to the controversial results found in the literature. While some studies found increases in antibody levels in HIV-infected adult patients,1, 15, 16 another found a reduction.17 Some hypotheses can be raised based on these distinct findings: inadequate antibody activity when compared with healthy individuals18, 19; presence of infectious process, when there is a critical point of antigen levels, in which the salivary antibodies are inefficient20; a greater pathogenicity of Candida strains in these patients, when compared to Candida strains isolated from healthy individuals.15 Another possibility that should not be forgotten is the degree of systemic compromise of these patients. Also as an infection increases or when it has already reached the stage of AIDS, the concentration of IgA-S tends to reduce.21
Even though the clinical parameters are the most important for clinical diagnosis of candidiasis and the verification of risk for infection development, the detection of these antibodies is useful not only as HIV-infection markers, but also to detect specific antibodies and is therefore an ally in the diagnosis of candidiasis in these patients. Therefore, considering oral colonization of Candida spp. in HIV-infected patients and oral candidiasis as a significant clinical manifestation of this disease, there is great relevance of studies reporting the detection of fungi-specific IgA antibodies in these patients to achieve a more precise diagnosis of the patient's condition. Therefore, this systematic review evaluates the levels of specific salivary immunoglobulins against C. albicans in HIV-infected adult patients.
Section snippets
Study selection criteria
The search strategy was based on PubMed, Web of Science, Google Scholar, Cochrane and EMBASE databases and only articles published before October 2008 were considered for review. A hand search was performed and the reference lists of these articles were also used for obtaining additional relevant publications that could have been missed during database searches (Table 1). Databases were searched to include only papers and abstracts in English. Terms used in this literature search are presented
Study characteristics
A total of 144 abstracts were initially identified in the electronic databases, but very few (n = 3) fulfilled the inclusion criteria (Table 1). Comparing the results between databases, PubMed provided the greatest diversity of abstracts despite the omission of a series of abstracts selected elsewhere. EMBASE and Google Scholar provided 12 and 27 references not found in PubMed, respectively. Web of Science provided seven references not found in any of the other databases. Because most of the
Discussion
As can be seen, there are few studies in the literature regarding this theme. Because systematic reviews are based on extremely rigorous inclusion and exclusion criteria, the number of articles tends to decrease, especially when further criteria are imposed by the author as occurred in the present study. The aim of this work was to quantify the levels of salivary immunoglobulin A antibodies to C. albicans in HIV-infected adult patients. As a result, some studies had to be excluded.17, 22, 23
Conclusions
It can be concluded that adequate IgA antibody responses to C. albicans appear to be maintained, since the levels of these antibodies were found to be higher in all studies selected. Although the findings found in this systematic review are quite strong, the scientific evidence should be interpreted carefully because there are few reports in the literature, either they lack important methodological details or they use different methodologies.
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