Physiology of murine B lymphocytes I. Life‐spans of anti‐m̀ and haptenated Ficoll (thymus‐independent antigen)‐reactive B cells

We have evaluated the life‐span of B lymphocytes by measuring the functional reactivity of normal B cells upon transfer into xid mice, which do not respond to anti‐μ, fluoresceinated‐Ficoll (FL‐Ficoll) and 2,4,6‐trinitrophenyl aminoethylcarbamylmethyl Ficoll (TNP‐Ficoll). After 4 days of transfer only 30–40% of anti‐μ‐reactive cells decayed leaving behind 60–70% of B cells which appeared to decay slowly. Even 10 days after transfer ˜ 40% of anti‐γ‐reactive B cells can be recovered from the recipients. This result demonstrates the existence of heterogeneity in the life‐spans of anti‐μ‐reactive B lymphocytes and that a major population (60–70%) of B cells persists beyond 4 days. Interestingly, the short‐lived B cell subpopulation was not detected when the decay of the antigen‐specific B cells was studied. Thus, TNP‐Ficoll and FL‐Ficoll‐reactive B cells were found to be long lived and such B cells did not decline at all, even 5 months after transfer into xid mice.