Quantity and quality of anti-hapten antibodies in normal and in T cell-deprived mice studied at the cellular level.

Abstract

The Immune response of normal mice as well as of thymus‐deprived (TxB) mice against 2 different hapten‐protein conjugates (NNP‐BSA and NNP‐CG) was tested at various times after immunization at the cellular level. Normal mice developed both direct and indirect plaque‐forming cells against the hapten, as determined by a modified local haemolysis in gel assay for detection of anti‐hapten antibody‐secreting cells. However, TxB mice produced direct plaque‐forming cells to the same extent as normal mice, whereas the indirect plaque‐forming cell response was greatly impaired. In fact, significantly elevated levels of indirect plaque‐forming cells were not detected in such mice. Studies on the affinity of secreted antibodies by means of hapten inhibition revealed that the indirect plaque‐forming cells derived from normal immunized mice could be inhibited by decreasing concentrations of free hapten with time after immunization, indicating a gradual increase in the number of cells secreting antibodies of high affinity. No such change was detected in normal or TxB mice with regard to antibodies giving rise to direct lysis, presumably IgM antibodies.