FIG. 4.

Defective humoral response to thymus-independent antigens and lack of a humoral response to a thymus-dependent antigen in p110δ-deficient mice. Wild-type (filled circles) or p110δ-deficient (open circles) mice were immunized with either TNP-LPS, a TI-I antigen (A); TNP-Ficoll, a TI-II antigen (B); or TNP-KLH, a T-dependent antigen (C). The serum TNP-specific immunoglobulin isotype response was measured by ELISA. The relative absorbance values at 405 nm for the indicated dilution are plotted for each individual animal. Mean values are indicated by boldface lines. Statistically significant differences (P < 0.05) are indicated (**).