Reiss, S. | Search bioRxiv

bioRxiv2019

Normal human lymph node T follicular helper cells and germinal center B cells accessed via fine needle aspirations

Germinal centers (GC) are critically important for the maturation of the antibody response and the generation of memory B cells, which are the basis for long-term protection from pathogens. Germinal centers only occur in lymphoid tissue, such as lymph nodes, and are not present in blood. Therefore, cells of the germinal center, including GC B cells and GC T follicular helper (TFH) cells, are not well-studied in humans under normal healthy conditions, due to the limited availability of healthy lymph node samples. We used a minimally invasive, routine clinical procedure, lymph node fine needle aspirations (LN FNAs), to obtain lymph node cells from healthy human subjects to establish benchmarks of GC cells under noninflammatory conditions. This study of 50 lymph nodes demonstrates that human LN FNAs are a safe and feasible technique for immunological research, and defines benchmarks for human GC biology. The findings indicate that assessment of the GC response via LN FNAs will have application to the study of human vaccination, allergy, and autoimmune disease.

immunology↗

bioRxiv2018

Slow delivery immunization enhances HIV neutralizing antibody and germinal center responses via modulation of immunodominance

The observation that humans can produce broadly neutralizing antibodies (bnAbs) against HIV-1 has generated enthusiasm about the potential for a bnAb vaccine against HIV-1. Conventional immunization strategies will likely be insufficient for the development of a bnAb HIV vaccine and vaccines to other difficult pathogens, due to the significant immunological hurdles posed, including B cell immunodominance and germinal center (GC) quantity and quality. Using longitudinal lymph node fine needle aspirates, we found that two independent methods of slow delivery immunization of rhesus macaques (RM) resulted in larger GCs, more robust and sustained GC Tfh cell responses, and GC B cells with improved Env-binding, which correlated with the development of ~20 to 30-fold higher titers of tier 2 HIV-1 nAbs. Using a new RM genomic immunoglobulin loci reference sequence, we identified differential IgV gene usage between slow delivery immunized and conventional bolus immunized animals. The most immunodominant IgV gene used by conventionally immunized animals was associated with many GC B cell lineages. Ab mapping of those GC B cell specificities demonstrated targeting of an immunodominant non-neutralizing trimer base epitope, while that response was muted in slow delivery immunized animals. Thus, alternative immunization strategies appear to enhance nAb development by altering GCs and modulating immunodominance of non-neutralizing epitopes.

immunology↗