Role of variable region gene expression and environmental selection in determining the antiphosphorylcholine B cell repertoire.

Abstract

To evaluate the role of environmental selective processes, as opposed to variable region gene expression, in the determination of B cell repertoire expression, we have assessed the phosphorylcholine (PC)-specific repertoire of precursor cells that remain in bone marrow cell populations after the removal of surface immunoglobulin (sIg)-bearing cells. Such cells are assumed to represent a stage in B cell maturation before the expression of sIg, and thus at a time when they have not as yet interfaced with environmental influences that operate through sIg receptors such as antigenic stimulation, tolerance, or antiidiotypic regulation. The repertoire as expressed in these cells, therefore, should reflect the readout of immunoglobulin variable region genes as they are expressed in progenitors to B cells. The results of these studies indicate that, as in mature primary B cell pools of BALB/c mice, the majority of PC-responsive sIg- bone marrow cells are of the T15 clonotype. Thus, environmental selective mechanisms would not appear to be required for the high frequency of B cells of the T15 idiotype in the primary B cell repertoire of BALB/c mice. Analysis of the sIg- bone marrow cells in (CBA/N X BALB/c)F1 male mice demonstrated that the deficit of PC-responsive mature B cells, which is a characteristic of this murine strain, must occur after receptor expression, since a normal frequency of PC-responsive and T15-expressing cells is present in their sIg- bone marrow population. Finally, these same mice were used to obtain bone marrow cell preparations from individual leg bones, so as to permit an analysis of the occurrence of T15+ and T15- clonotypes within individual bone marrow populations. The findings from these studies indicate that T15+ B cells occur as a high frequency event within bone marrow generative cell pools. Furthermore, bone marrow populations that are positive for PC-responsive precursor cells often display multiple copies of such precursor cells that are exclusively either T15+ or T15-. This finding indicates that clonal expansion of cells within the B cell lineage apparently occurs before immunoglobulin receptor acquisition.

The Protection: The Unit of Humoral Immunity Selected by Evolution

“…It is fortuitous, then, that the correction factor for efficiency of the assay and our theoretical value of FIT happen to be close. Before discussing the uncorrected data, how are they explained by Klinman & Stone (1983)?…”

The Immune Response to the Hapten NP in C57BL/6 Mice: Insights into the Structure of the B‐Cell Repertoire

“…This could reflect the basic organization of the resting repertoire. Klinman & Stone (1983) arrived at very similar conclusions from an analysis of the PC-specific repertoire of precursor cells in the bone marrow. The apparent diversity in the resting repertoire would be reduced to the extent that each individual clone was expanded.…”

Diversity 1990

“…In 1983 we also reported that, while newly developing B cells bearing various tested clonotypes were absent from the marrow of most large bones, bone marrows that did express a given clonotype often expressed more than one cell of that clonotype (Klinman & Stone 1983). Since bone marrow B cells do not appear to divide after L-chain rearrangement and slg expression, we proposed that the "clonal expansion" evidenced by this "jackpotting" of clonotypes in individual bone marrows was likely, at least in part, to be the product of considerable clonal expansion after Vi,-Di,-Jh rearrangement.…”

“…The "predetermined permutation" model was proposed, not as Cohn & Langman suggest, to account for the sequential acquisition of neonatal specificities, but rather to accomodate the high frequency of expression in BALB/c mice of anti-PC antibodies identical in VH and VL to the TEPC15 myeloma protein. In 1983 we demonstrated that "when T15 is expressed, it is not represented as inordinately large cell clones, but rather the expression of B cells bearing the T15 idiotype is an extraordinarily frequent event during repertoire generation" (Klinman & Stone 1983). (Note: Cohn & Langman quote us as concluding just the opposite).…”