1c). As CD56dim NK cells are the major population MLN0128 cost of NK cells, it was not surprising to find

reduced numbers in the HIV-1 mono-infected group, mirroring the results obtained for total NK cells (Fig. 1b). Although previous studies have indicated an increase in the frequency of CD56neg NK cells in HIV-1-infected subjects,23 we did not observe either an elevated number (Fig. 1c) or an elevated frequency (data not shown) in this population of Brazilian subjects, either with or without concomitant HSV-2 infection. It is well established that NK cells are important in the immune response controlling herpesviruses. In particular, HSV pathogenesis in both humans and mouse models is enhanced in the absence of NK cells, when NK cell function is inhibited, or when innate accessory cells required for activation of dendritic cells (DCs), plasmacytoid DCs and macrophages IWR-1 chemical structure are absent or dysfunctional. In HIV-1 infection, alterations in the number and function of NK cells have been described previously.1,24–29 We evaluated the function of NK cells from HIV-1 mono-infected subjects,

HSV-2 co-infected subjects, and healthy HIV-1-seronegative controls. We stimulated PBMCs from these individuals by co-culture with the MHC class I-deficient K-562 erythroleukemia cell line.30 K-562 cells do not express MHC class I proteins (HLA-A, HLA-B, HLA-C, HLA-E or HLA-G) on their surface; therefore, they fail to express any known ligands for the inhibitory and activating KIRs. We detected an increased absolute number of degranulating NK cells, as indicated by levels of CD107 antibody staining (Fig. 2). The number of CD107+ NK cells in HSV-2 co-infected subjects was Vasopressin Receptor increased relative to HIV-1 mono-infected subjects in stimulated cultures (263 cells/μl versus 195 cells/μl, respectively; P = 0·018) and was not different from that in HIV-1-seronegative healthy control subjects. Furthermore, in cultures with no stimulation, the number of functional

NK cells was significantly depressed in HIV-1 mono-infected subjects compared with healthy control subjects (121 cells/μl versus 198 cells/μl, respectively; P = 0·007). We assessed the relationship between HIV-1 plasma viral load and the number of NK cells expressing the natural cytotoxicity receptors NKp30 and NKp46 in HIV-1 mono-infected and HSV-2 co-infected subjects (Fig. 3). Although there was no difference in the mean number or frequency of NKp30- or NKp46-positive cells between groups (Fig. 3a), or in HIV-1 plasma viral load (Fig. 1a), an inverse correlation was observed in HIV-1 mono-infected subjects for both NK cells receptors (Fig. 3b,c). This correlation was not observed in HSV-2 co-infected subjects. In HIV-1 mono-infected subjects, this inverse correlation was significant for NKp46 (P = 0·046).