The asynchronous development of immunological memory in helper (T) and precursor (B) cell lines

Abstract

Abstract A simple method is described for distinguishing helper (T) and precursor (B) immunological memory: it depends on the sequential use of 2 cross‐reacting antigens for priming and challenge. Using cow and sheep erythrocytes, we have followed the asynchronous development of helper and precursor memory. Helper (T) memory is optimal 4 – 6 days after a wide range of antigen doses (2 × 10 4 –2 × 10 9 red blood cells). It reaches rather higher levels after very small injections, but persists longer after high doses. Precursor (B) memory requires a large amount of antigen for optimal development (2 × 10 7 – 2 × 10 9 red blood cells). It increases for at least 2 months after priming. B‐memory cells defined by the cross‐reactive criterion are insensitive to anti‐theta serum but require the presence of T cells for their effective stimulation by antigen. Precursor memory does not appear to be carried by the antibody‐forming cells themselves. It is more sensitive to irradiation damage than T memory. Memory of either kind leads to increased production of both IgM and IgG antibody‐forming cells. Helper memory cells seem to be able to interact with virgin B cells in the normal spleen.