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Thursday, January 29, 2015
HIV and AIDS
What Concentrations of Ig G Antibodies To HIV Are Present In Vaginal Fluid?
I`m trying to find out what concentrations of Ig G antibodies to HIV are present in vaginal fluid?
The Answer to this question is not simple. The concentration of antibodies directed to a given antigen cannot be measured as milligrams or micrograms per milliliter. Antibodies are quantified as a `titer`: The sample is serially diluted and the titer is reported as the maximal dilution that is able to give a positive assay. There are several assays used to detect and measure antibodies: Enzyme-linked Immunoassay (ELISA), Agglutination, Western-blot, or even viral neutralization.
The titer obtained for a given sample may vary depending on the assay utilized. Also, when one wants to quantify an antibody, it is important to have a defined antigen: HIV is a complex structure and contains several antigens like gp120, p24, gp160. The titer to each one of them may be different. The titer also varies from person to person.
I have not seen a `normal` range of antibody titers to HIV in serum, semen, saliva or vaginal secretions, that has been determined. I searched the literature and found several small studies in which some measurement of HIV specific antibodies were measured in bodily fluids. In a particular study performed in Africa it was reported that the titers of antiHIV antibodies (IgG) in vaginal secretions roughly correlated with the titers in serum of the same patient. The presence of concomitant inflammation in the vagina appeared to increase the amount of antibody present in the secretions. It is noteworthy that the antibodies present in vaginal secretions (and in serum) of infected persons are not neutralizing, i.e. do not inhibit the invasion of susceptible cell lines to a lab strain of HIV. Some effort in vaccine development has been concentrated on the induction of neutralizing antibodies in mucosal surfaces, and there are reports of some progress in simian models of SIV.
In summary: Anti-HIV IgG is present in the vaginal secretions. The concentration is not defined, as different assays produce different results. Multiple factors like local inflammation, transudation from serum, local production may induce variation the amount of total immunoglobulin and the titer of HIV-specific antibody in a given individual. Please see the references below.
Mucosal immune responses in four distinct compartments of women infected with human immunodeficiency virus type 1: a comparison by site and correlation with clinical information. Artenstein AW; VanCott TC; Sitz KV; Robb ML; Wagner KF; Veit SC; Rogers AF; Garner RP; Byron JW; Burnett PR; Birx DL JOURNAL OF INFECTIOUS DISEASES vol. 175, no. 2 (1997 Feb): 265-71 Quantitation of mediators of inflammation and immunity in genital tract secretions and their relevance to HIV type 1 transmission. Anderson DJ; Politch JA; Tucker LD; Fichorova R; Haimovici F; Tuomala RE; Mayer KH AIDS RESEARCH AND HUMAN RETROVIRUSES vol. 14 Suppl 1 (1998 Apr): S43-9 HIV-1-specific mucosal IgA in a cohort of HIV-1-resistant Kenyan sex workers. Kaul R; Trabattoni D; Bwayo JJ; Arienti D; Zagliani A; Mwangi FM; Kariuki C; Ngugi EN; MacDonald KS; Ball TB; Clerici M; Plummer FA AIDS vol. 13, no. 1 (1999 Jan 14): 23-9. Intranasal immunization of a DNA vaccine with IL-12- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-expressing plasmids in liposomes induces strong mucosal and cell-mediated immune responses against HIV-1 antigens. Okada E; Sasaki S; Ishii N; Aoki I; Yasuda T; Nishioka K; Fukushima J; Miyazaki J; Wahren B; Okuda K JOURNAL OF IMMUNOLOGY vol. 159, no. 7 (1997 Oct 1): 3638-47
Francisco Gomez, MD
College of Medicine
University of Cincinnati