Cell Counter QA.pdf

1. Are the cells stained or have a fluorescent detection system and what does the signal to background noise look like?

Yes, the cells will be stained with Acridine Orange (AO) and Propidium Iodide (PI) to obtain accurate and reproducible results for cell viability measurement. It usually has a relatively low signal-to-noise ratio.

2. What are the cells themselves, is the team enumerating the cells specifically or is it a foci based assay, what is the typical size range?

Most of the cells are human peripheral blood mononuclear cells (PBMCs), which isolated from human peripheral blood by our team. It’s a heterogeneous population of blood cells with a single round nucleus and include macrophages, dendritic cells, monocytes, and lymphocytes. The typical size range is 7-12 µm. Other cell lines are including HEK 293T (11-15 µm), DC-SIGN Raji cells (5-8 µm), K562 (about 20 µm), Vero cells (about 17 µm) et al. Yes, the cell counting is a foci-based assay that the lasers will focus on the dyes on cells for counting the cell numbers.

3. We have been involved with covid since the start of the pandemic as well as influenza for the last 10+ years, can you tell us more about the LINKS study mentioned in the RFQ?

The Long-term Immunity against Novel and Known Strains of SARS-CoV-2 (LINKS-COVID) study evaluated the adaptive immune responses in U.S. active-duty personnel who completed a COVID-19 primary vaccine series and with heterogenous SARS-CoV-2 vaccination and infection histories to 3 previously dominant variants (Ancestral, Delta, BA.5) and 3 circulating variants (XBB.1.5, EG.5, and BA.2.86) in late 2023. The study has been published on The Journal of Infectious Diseases earlier this year (Huy C Nguyen et al., 2024). The LINKS-COVID 2.0 is a continuation of LINKS-COVID study with larger sample size and novel circulating variants in late 2024.

4. We have many different models with different capabilities; many of them of multi-role/multi-function, we would like to get some of these early questions taken care to not waste anyone’s time if we’re not a good fit. Are you able to put us in touch with the end users or forward along our questions/answers?

The government’s minimum requirements are included in the RFQ/minimum requirements document.

Questions are answered by the end-user and responses will be posted in SAM.gov. Vendor direct contact with end-users during an open solicitation/RFQ is not allowed.

5. What are the goals of their work? Cell therapy, vaccines, etc?

The goals of our work are including immune surveillance, vaccine platform development, and antiviral drug screening and testing.

6. Please advise what cell types they are working with.

Most of the cells are human peripheral blood mononuclear cells (PBMCs) which isolated from human peripheral blood and are a heterogeneous population of blood cells with a single round nucleus and include macrophages, dendritic cells, monocytes, and lymphocytes. Other cell lines are including HEK 293T, DC-SIGN Raji cells, K562 cells, and Vero cells et al.

7. Will this instrument be used in a GMP setting?

No, this instrument will not be used in a GMP setting.