Abstract
Pre-B cells, precursors of surface IgM bearing B cells, are defined as cells in hemopoietic tissues that lack surface immunoglobulins (sIg-) but produce small amounts of cytoplasmic IgM components (cμ+). To determine whether Ig light chains and other heavy chains are also produced by pre-B cells, we have used affinity purified goat antibodies to human Ig determinants (μ, δ, γ, α, κ, λ) in immunofluorescent and immunochemical assays of bone marrow samples. All sIg+ B cells and cIg+ plasma cells were costained with a mixture of anti-κ and anti-λ antibodies. None of the cIg+ plasma cells were double stained with anti-κ and anti-λ. κ/λ ratios of sμ+ B cells and cIg+ plasma cells from 5 normal adult marrows were 1.4 ± 0.2 and 1.3 ± 0.3 (mean ± S.D.), respectively. Frequencies (%) of pre-B cells (sIg-cμ+), κ+ pre-B cells (sIg-Cμ+) and λ+ pre-B cells (sIg-cμ+) among nucleated bone marrow cells were 0.69 ± 0.38, 0.017 ± 0.015 and ≤0.008, respectively. Pre-B cells expressing Ig heavy chains other than μ were not seen among 30,000 or more nucleated marrow cells. Analysis of bone marrow cells from two patients with X-linked agammaglobulinemia revealed μ chain synthesis only, as determined by SDS polyacrylamide gel electrophoresis. Our data indicate that (i) >90% of human pre-B cells express μ chains only, suggesting asynchronous onset of heavy and light chain synthesis, and (ii) heavy chain switching is a rare event at this stage in differentiation.
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Kubagawa, H., Gathings, W., Levitt, D. et al. 940 ASYNCHRONOUS ONSET OF μ AND LIGHT CHAIN SYNTHESIS BY HUMAN PRE-B CELLS. Pediatr Res 15 (Suppl 4), 599 (1981). https://doi.org/10.1203/00006450-198104001-00965
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DOI: https://doi.org/10.1203/00006450-198104001-00965