Ovalbumin‐Specific Human B‐Cell Activation and Maturation: The Absence of Final Maturation is Due to the Incapacity of Ovalbumin‐Activated T Cells to Produce Maturation Factors

By means of a panel of monoclonal antibodies it is demonstrated that, in cultures of human peripheral blood mononuclear cells (PBMC) with the T‐cell dependent (TD) antigen ovalbumin (OA), responding B ceils are activated from the resting Mate The differentiation of the activated B cells to high rate‐secreting plasma blasts, however, is attested in an early activation phase, in which they can be detected at low rate‐secreting plaque‐forming cell. The arrest does not occur when stimulation with OA occurs in the presence of antigen‐nonspecific activation and maturation factors, which are provided in the culture by the anamnestic response to the TD antigen tetanus toxoid.