The Scientist

1. What made you choose scientific research as a career path?

I first realized that I wanted to be a scientist when I worked as an undergraduate research assistant in a microcirculation lab at the UCSD Bioengineering Department. I remember being enamored with the process of coming up with a creative idea to answer a scientific question, using my hands and reagents to translate the idea, and assessing what to do next based on the results. This process didn't feel like work, it felt like fun. During this time, it was such an honor to have the privilege of cutting frozen pieces of intestines all night and watching postdoctoral fellows perform rat surgeries. I was completely mesmerized with the fun tools in the lab that allowed us to answer important questions.

2. Who is your scientific idol?

Instead of one specific person, I have several scientific idols who use cutting edge techniques to answer critical immunological questions. These individuals include my mentor, Dr. Marc Jenkins, and other leaders in their field including Drs. Michel Nussenzweig, Jason Cyster and Darrell Irvine.

3. What is your role in the Jenkins lab?

The focus of my work is to better understand the factors that drive the differentiation program of different CD4⁺ T helper cell subsets. I am also interested in identifying how each of these subsets contribute to different aspects of the B cell response, such as the formation of plasma cells, germinal center B cells and memory B cells.

The Science

1. What do you consider to be the most important advances in the field of CD4⁺ T cells and MHCII biology, over the past 10 years?

One important advance is the use of peptide:MHCII tetramer enrichment to identify rare polyclonal antigen-specific CD4⁺ T cells. This technology allows us to reasonably study physiological CD4⁺ T cell responses. Another advance is the implementation of two-photon microscopy to visualize the movement of CD4⁺ T cells and their interactions with antigen-presenting cells during an immune response. While flow cytometry is central to a lot of work done in immunology, a limitation is that cells are pooled together and analyzed during a snapshot in time. Two-photon microscopy provides information on how different immune cell types expand, localize and interact with each other during an immune response.

2. What advances do you hope the field will achieve in the next 5 years?

The field is accumulating knowledge relating to the factors promoting different types of CD4⁺ T cells. I hope that in the next 5 years, the field can implement this knowledge into potential treatments that modulate CD4⁺ T cell activity to treat immunological problems such as autoimmunity and cancer.

3. What are the main technical challenges currently facing the CD4⁺ T cell immunology field?

One technical challenge is conducting an in-depth analysis on polyclonal antigen-specific CD4⁺ T cells. For example, we can identify and phenotype these cells using tetramer enrichment and flow cytometry, but it is not feasible to use two photon microscopy to observe their interactions during an immune response due to the rare nature of these cells. Furthermore, adoptive transfer of these cells into recipient hosts to understand how they may affect the recipient immune response is challenging. Given that there is approximately a 10% park rate among total transferred cells, it is incredibly difficult to assess any changes in mice that received so few polyclonal CD4⁺ T cells.

EasySep™

1. Why does your lab use EasySep™?

We use for enrichment of polyclonal antigen-specific CD4⁺ T cells and B cells. This is done by staining cell suspensions with fluorochrome-labelled peptide:MHCII or B cell tetramers. The cells are then incubated with anti-fluorochrome EasySep™ kits allowing for enrichment with the EasySep™ magnet. Our lab has adopted EasySep™ for two reasons:

1. It is more cost-effective compared to competitor magnetic isolation.
2. Enriched cells obtained from the EasySep™ magnet have fewer non-specific cells than the competitor magnet. This reduces the time required at the flow cytometer to collect events and also results in a more accurate representation of the data because analyzed cells contain less background.

2. How has EasySep™ enabled your research?

has allowed us to enrich for rare populations of cells so that we can reasonably analyze such cells. Without tetramer enrichment, we would not only have to spend copious amounts of time at the flow cytometer, but the analysis would be tainted with high levels of background. Thus, EasySep™ has allowed us to accurately and efficiently phenotype our cells of interest. EasySep™ helped our lab analyze rare polyclonal antigen-specific CD4⁺ T and B cell responses in an accurate and cost-effective manner.

View related EasySep™ CD4+ T cell products
View related EasySep™ B cell products

STEMCELL's Scientific Summaries

On the role of CD4⁺ T helper cell subsets in the B cell response

CD4⁺ T cells are required to promote robust B cell function and antibody response. The expression of IL-4, IL-21 and CD40L by CD4⁺ T cells, for example, have been shown to play a role in promoting B cell class switching, proliferation and germinal centre formation¹. Since then, T follicular helper (Tfh) cells have been identified as a new CD4⁺ T cell subset that uses these mechanisms to provide help to B cells². The understanding of Tfh cell biology has been propelled by the finding that BCL-6 is their lineage-defining transcription factor. More recently, the roles of Bcl6-interacting corepressor (BCOR)³ and the transcription factors LEF-1 and TCF-1⁴, have also been implicated in the molecular mechanism behind Tfh differentiation and function. It is now clear that Tfh cells are a specialized T cell subset that is responsible for providing help to B cells; however, as an increasing variety of T cell subsets are being discovered, their potential contributions to the B cell response will need to be investigated.

On the analysis of antigen-specific CD4⁺ T cells and B cells

A distinguishing feature of adaptive immunity is its ability to respond in an antigen-specific manner. Fluorochrome-conjugated tetrameric MHC/peptide complexes have provided immunologists with a powerful tool for the detection of antigen-specific T cells ⁵. Since then, immunologists have continually worked to improve the use of this technology. For example, a method for the detection multiple populations of antigen-specific T cells in parallel using MHC/peptide tetramers have been developed⁶. With the discovery of new technologies, such as mass cytometry and high-throughput sequencing, immunologists can now more comprehensively analyze antigen-specific T cell responses⁷. These new methodologies will aid researchers to evaluate antigen-specific T cell responses to various immune challenges, and can also be used to measure the efficacy of immune therapies.