HUMORAL IMMUNITY DUE TO LONG-LIVED PLASMA-CELLS

Conventional models suggest that long-term antibody responses are main tained by the continuous differentiation of memory B cells into antibo dy-secreting plasma cells. This is based on the notion that plasma cel ls are short-lived and need to be continually replenished by memory B cells. We examined the issue of plasma cell longevity by following the persistence of LCMV-specific antibody and plasma cell numbers after i n vivo depletion of memory B cells and by adoptive transfer of virus-s pecific plasma cells into naive mice. The results show that a substant ial fraction of plasma cells can survive and continue to secrete antib ody for extended periods of time (>1 year) in the absence of any detec table memory B cells. This study documents the existence of long-lived plasma cells and demonstrates a new mechanism by which humoral immuni ty is maintained.