Role of IgD in the immune response and tolerance. II. Precursor analysis of murine B cells separated on the basis of surface IgD or treated with an anti-delta serum.

Precursor analysis of the function of murine B cells with surface IgD has been accomplished using an alloantiserum directed against a delta allotype and cellular affinity chromatography. Spleen cells from 3-week-old C57BL.Ige mice were treated with a TNP-labeled anti-delta allotype serum, washed and passed through an anti-TNP affinity column. The cells passing such a column were depleted of IgD-bearing lymphocytes by immunofluorescence and also showed a greatly reduced ability to develop into specific antibody-forming cell clones vs. the fluorescein (FL) hapten in a limiting dilution microculture system in vitro. In contrast, the IgD-bearing cells eluted from such columns were slightly enriched in precursor activity compared to the original population. Moreover, brief treatment with anti-delta serum alone produced a partial reduction in the precursor frequency vs. FL with C57BL.Ige spleen cells (which bear the appropriate delta allotype) but not C57BL/6 spleen cells (which are negative for this delta allotype). This effect varied with the age of the spleen donor, but was most dramatic with splenocytes from 2 to 3-week-old mice. This contrasts with the effect of anti-mu pretreatment, which only inhibited neonatal precursors. The results are interpreted in terms of the maturation of murine B cells and the function of IgD and IgM receptors in triggering an immune response.