In vitro synthesis of IgE by human peripheral blood leucocytes: VI. Seasonal variations in synthesis of rye pollen (Lolium perenne) specific IgE.
Fractionation by Percoll density centrifugation of peripheral blood leucocyte cells, from atopic subjects with seasonal hay fever, unmasked IgE-B cell populations whose individual capacities to synthesize IgE in vitro were obscured in cultures of unfractionated B cells. B cell cultures from all six subjects in the study released rye pollen-specific IgE during the 6 days of culture, but actual synthesis was significant only in October, the pollen season. Synthesis in October occurred most frequently in cultures of mature, low density B cells, which generally responded to the addition of autologous T cells with enhanced synthesis (T-help). T-help was also found for high density B cells in the mid-winter (July) cultures. Total IgE synthesis in vitro demonstrated a less seasonal relationship, although it tended to be maximal for low density B cell cultures in October and for high density B cells in May. All B cell cultures contained preformed total and rye-specific IgE antibody which persisted throughout the pre- and post-pollen seasons, particularly in the low density B cell fractions, even in the absence of de novo synthesis. Moreover, the intracellular levels of rye pollen-specific IgE antibody were often higher in the winter than in the peak of the pollen season. The relevance of this preformed IgE remains to be established.