Human peripheral blood lymphocytes from recently vaccinated individuals produce both type-specific and intertypic cross-reacting neutralizing antibody on in vitro stimulation with one type of poliovirus.

An in vitro system of poliovirus-specific antibody production by peripheral blood B cells on stimulation by the virus has been developed. Virus-neutralizing antibodies in culture supernatant fluids, or virus-specific antibody-secreting cells (ASC) were detected by microneutralization assay and ELISA-SPOT test, respectively. After booster immunization with polio vaccine, anti-poliovirus-neutralizing ASC were present in circulation. This response was measurable between 5 and 12 days after booster vaccination. At between 12 and 90 days, another subset of B cells was found in peripheral blood that only produced poliovirus-specific neutralizing antibody after in vitro antigenic stimulation. The in vitro virus-induced response required B cells, monocytes, and T4+ (T helper) cells, and was shown to result from de novo protein synthesis. The anti-poliovirus-neutralizing response in vitro could be dissected in a type-specific and intertypic cross-reactive response by using various antigen concentrations for in vitro stimulation. Evidence was obtained by absorption studies for the existence of intertypic cross-reactive neutralization-inducing epitopes.