Table I.

IL-21 induces the production of IgG1 and IgG3 by CD40-activated CD19+CD27 human B cellsa

Culture ConditionsIgG1IgG2IgG3IgG4
Expt. 1Expt. 2Expt. 3Expt. 1Expt. 2Expt. 1Expt. 2Expt. 3Expt. 1Expt. 2
CD19+CD27 B cells
 CD40 + IL-4711≤1≤1≤1≤1≤1≤1≤1
 CD40 + IL-21606117236≤1≤1331280≤1≤1
 CD40 + IL-4 + IL-21909216290≤1≤112224135≤1≤1
CD19+CD27+ B cells
 CD40 + IL-417279496803885646172≤1
 CD40 + IL-219,7822,8357,0691621343626338251228
 CD40 + IL-4 + IL-2120,1187,05428,0943295628882441650744109
  • a Purified CD19+CD27 and CD19+CD27+ splenic B cells (106 cells/ml) (Expts. 1 and 2) or surface IgG+-depleted CD19+CD27 B cells (Expt. 3) were stimulated with 1 μg/ml anti-CD40 mAb in the presence or absence of rIL-4 and/or rIL-21 (both cytokines at 10 ng/ml). IgG levels were determined by isotype-specific ELISA after 12 days of culture and expressed as nanograms per milliliter. Three representative experiments from a total of five, using different spleen samples, are shown.