Migration and differentiation of bone marrow lymphocytes: Development of surface immunoglobulin, Fc receptor, complement receptor, and functional responsiveness as studied with anti-allotype serum

Abstract

Immunofluorescent studies using fluorescein isothiocyanate-conjugated mouse anti-allotype antibody were carried out to study the migration pattern and the development of surface Ig (SIg), Fc receptor for IgG (FcRγ), and complement receptor (CR) or mouse bone marrow lymphocytes following intravenous injection into congenic mice. After transfer of bone marrow cells from CSW mice into untreated congenic CWB mice, the absolute number of donor-type SIg-bearing (SIg +) cells and the proportion of either FcRγ- or CR-bearing (FcRγ + or CR +) cells in donor-type SIg + cells were evaluated in the recipient spleen and the results were compared with those obtained after the transfer of CSW spleen cells. After injection of donor bone marrow cells, detectable donor-type SIg + cells, although few initially, increased from day 1 to Day 2 and reached a plateau thereafter. The proportion of FcRγ + cells in donor-type SIg + cells, although very low in the donor marrow inoculum, increased progressively after 1 day to reach a maximum at Day 5 (90%). On the other hand, following the transfer of spleen cells, the proportion of FcRγ + cells remained at high levels (90%) for 5 days after transfer. Likewise, the proportion of CR + cells in donor-type SIg + cells was very low (<1%) in the original donor bone marrow cells but high (60%) in the donor spleen cells. However, in transferring bone marrow cells this proportion also increased in the recipient spleen to reach a maximum (49%) at Day 5 although it was lower compared to the percentage of FcRγ + cells in donor SIg + cells. Furthermore, the ability of functional responsiveness to antigen was also examined in the same system by detecting plaque-forming cells (PFC) from donor origin. In transferring donor bone marrow cells into recipient, the participation of donor cells in the PFC response was very low when the recipients were primed with sheep red blood cells at Day 3 after transfer. However, when the recipients were primed at Days 7 to 21 after transfer, increasing numbers of the donor marrow-derived cells were involved in the PFC response. Thus, the present study demonstrates that the bone marrow-derived lymphocytes, albeit lacking both distinctive surface receptors (IgM, FcRγ, CR) and the functional responsiveness to antigen, continue their development along the B-cell lineage after migrating into the spleen, as evidenced by the surface receptor expression and participation in the antibody response.