A combined HIV-1 protein bead array for serology assay and T-cell subset immunophenotyping with a hybrid flow cytometer: a step in the direction of a comprehensive multitasking instrument platform for infectious disease diagnosis and monitoring

The role of interleukin-12 in the heavy metal-elicited immunomodulation: relevance of various evaluation methods

Background

Increasing evidence exists that heavy metals modulate T helper cell (Th) responses and thereby elicit various pathological manifestation. Interleukin (IL)-12, a crucial innate cytokine, was found to be regulated by such xenobiotic agents. This study aimed at testing whether IL-12 profiles may be indicative of heavy metals-induced immunomodulation.

Methods

Human immunocompetent cells, activated either by monoclonal antibodies or heat-killed Salmonella enterica, were cultured in the absence or presence of cadmium (Cd) acetate or mercuric (Hg) chloride. In vivo experiments were set up where BALB/c mice were exposed to sub-lethal doses of Cd or Hg salts for 3 or 5 weeks. Cytotoxicity was assessed by MTT-reduction assay. Modulation of cytokine profiles was evaluated by enzyme-linked immunosorbent assay (ELISA), cytometric bead-based array (CBA) and real-time polymerase chain reaction (RT-PCR); the relevance of these methods of cytokine quantification was explored.

Results

Modulation of IL-12 profiles in Cd- or Hg-exposed human PBMC was dose-dependent and significantly related to IFN-γ levels as well as to the Th1- or Th2-polarized responses. Similarly, skewing the Th1/Th2 ratios in vivo correlated significantly with up- or down-regulation of IL-12 levels in both cases of investigated metals.

Conclusion

It can be inferred that: (i) IL-12 profiles alone may represent a relevant indicator of heavy metal-induced immune modulation; (ii) evaluating cytokine profiles by CBA is relevant and can adequately replace other methods such as ELISA and RT-PCR in basic research as well as in immune diagnostics; and (iii) targeting IL-12 in therapeutic approaches may be promising to modify Th1/Th2-associated immune disorders.

Reagents and instruments for multiplexed analysis using microparticles

Multiplexed molecular analysis by means of flow cytometry using optically encoded microspheres is a rapidly expanding application that has its roots in the earliest days of flow cytometry. The approach is driven by increasing demand for analytical methods to measure large numbers of biomolecules quantitatively and sensitively in small volumes of sample. Encoded microspheres and flow cytometry have been employed for a wide range of multiplexed molecular analysis, and detailed protocols for many of these have been developed. The goal of this unit is to provide an overview of the concepts, instruments, and reagents that enable these assays.

Flow cytometry as the spearhead for delivering sustainable and versatile laboratory services to HIV-burdened health care systems of the developing world: a Caribbean model

HIV is targeting the developing nations of the world, threatening their economic development, overwhelming public health systems, and depleting human capital. The Caribbean is no exception, with the second highest incidence of HIV/AIDS outside Sub-Saharan Africa, sharing similar mixed fortunes from a postcolonial heritage, limited resources, and an HIV population dispersed in small population centers. Here we share the experience of Barbados, an island state of 280,000 people, in mounting a holistic and sustainable program against HIV/AIDS. At the forefront of this response has been the growth in clinical flow cytometry used for CD4 monitoring, which has prompted a welcome expansion in diagnostic capacity even beyond HIV/AIDS. A pan-Caribbean extension to Barbados' program has been the founding of the Caribbean Cytometry & Analytical Society (CCAS), which acts as a regional forum to accelerate technology transfer and develop the human resources needed to mount an effective response against HIV/AIDS. The 4th CCAS workshop in 2007 produced a consensus statement on the desirable characteristics for a "diagnostic dream machine": a simple-to-use, rugged flow cytometer capable of carrying out multiple diagnostic functions at the point of patient care in rural or island settings of the developing world, including CD4 count, blood count, and opportunistic infections, without the need for a supply cold-chain or dependable power source. It is our ambitious vision that the spread of flow cytometry, primarily to monitor CD4 in HIV/AIDS, can act as a Trojan horse to deliver better general and specialized diagnostic services to the developing world.

A two-dimensional suspension array system by coupling field flow fractionation to flow cytometry

Flow field flow fractionation (Fl-FFF) was coupled to flow cytometry to improve the performance of suspension arrays. Size-based separation of the protein-conjugated microspheres by Fl-FFF was performed and the results demonstrated that, the separation could tolerate a wide range of carrier fluid conditions (pH values, salt concentrations, and buffer compositions) favorable for immunoassays. The immuno-complex remained intact during Fl-FFF, as revealed by fluorescence measurements before and after the Fl-FFF separation, and SDS-PAGE of the eluted proteins. The sample throughput of the suspension array can be increased several folds by using particles of different sizes and separating them with Fl-FFF before flow cytometric measurement. Moreover, the gel result hinted that the continuous wash inside the Fl-FFF system may lower the assay background, another possible advantage of the two-dimensional suspension array system.