Probing the cellular basis for immunologic memory: approaching functional distinctions between primed and unprimed...

The physiologic distinctions between secondary and primary lymphoid populations remain largely conceptual. Altered activation, differentiation, and compartmentalization properties likely underlie these differences, but little precise knowledge of how these parameters are affected by antigen priming exists. Because lymphoid populations are dynamic entities and priming is a temporal process, lineage and life span analyses of definable subpopulations are required for the design and interpretation of experiments to probe functional distinctions between primed versus unprimed B-cell populations. Subsequent studies, which address differences in activation requirements and collaborative potential of primed versus unprimed B-cells are further required to evaluate the cellular basis of immunologic memory. Recent advances in the ability to dissect lymphoid differentiation subsets and lineages, coupled with a rapidly expanding knowledge of molecules which mediate B-lymphocyte growth and differentiation, render these possibilities amenable to experimental analysis.