B Cell ELISPOT Testing
Antibody molecules in serum have a relatively short half-life, on the order of days to weeks and therefore their presence in serum depends on ongoing production by B-cell-derived plasma cells. In the course of an immune response, naïve antigen-specific B cells become activated by the antigen, and by antigen-specific CD4 T-helper cells. As a consequence of activation, the B cells differentiate into plasma cells that produce antibodies; at the same time, long-lived memory B cells also emerge. These memory cells can give rise to new generations of plasma cells in the presence of persisting/reappearing antigens and T-cell-help, or in the absence of antigens, long-lived plasma cells can continue to spontaneously secrete antibodies. In either case, the presence of antibodies in serum of individuals results from an active, ongoing antibody synthesis process that may or may not reflect previous antigen exposure. For example, human donors tend to become seronegative over time after vaccinations e.g. with tetanus toxoid and diphtheria, requiring booster immunizations. In other cases, such as vaccinations with vaccinia virus, antibodies persist lifelong, even if the infectious agent has been cleared decades ago. In order to determine which of these scenarios applies to the antigen specific B cell immunity for the given to be evaluated immune responses measurements of direct detection of memory B cells could be performed from the PBMC to more reliable revealing the preexisting immunological memory to the newly induced B cell immune response. CTL is specialized in performing antigen specific Plasma B cell or memory B cell antibody secreting cells (ASC) evaluation in our contract laboratory which is vital for basic research, drug discovery, and management of a range of important diseases.
The ELISPOT technique allows researchers to generate secretory footprints in the form of colored spots within a 96-well plate. These images can then be scanned and counted, and readily evaluated for statistical significance. The ELISPOT method can therefore be used to determine whether a patient population responds positively or negatively to a vaccine, drug or biological product, and in addition, measure the extent of each person’s immune response preexisting or newly introduced.
CTL’s invaluable expertise (see publications) encompasses a wide range of assay types, thanks to its experience in working with clients to optimize, qualify, and validate test methods for various test systems—human, NHP, monkey, mouse, rat, pig, and more. Please see list of CTL's B cell ELISPOT Kits available as these possible B cell readouts are available to be used by our contract laboratory.