Sequential expression of B lymphocyte surface antigens in vitro

✍ Scribed by Joan Abbott; Kin Ngiam

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 693 KB
• Volume: 11
• Category: Article
• ISSN: 0014-2980
• DOI: 10.1002/eji.1830110512

✦ Synopsis

Abstract

Serological techniques were used to examine the process of sequential surface antigen expression on differentiating B cells in vitro. A 4‐day culture system is described in which bone marrow lymphocytes from neonatal mice acquire in sequence the ability to express Lyb‐2, IgM, Ia and IgD in response to a 3‐h‐induction with E. coli lipopoly‐saccharide (LPS). Lyb‐2 can be induced on day 1, IgM can be induced after 24 h, Ia after 48 h and IgD only after 96 h in culture. This sequence mimics the order of appearance of B cell surface antigens during ontogeny. When DNA synthesis is blocked from 0–24 h with hydroxyurea (HU), all surface antigens can be induced simultaneously by LPS. Immunoselection of one antigen‐bearing population results in the loss of cells bearing other B cell antigens indicating that the surface antigens are induced on the same cells. When both HU and LPS were added to the cultures from the start, IgM appears after 11–14 h, Ia after 14–15 h and IgD only after 19 h. Induction of antigen was demonstrated by the cytotoxicity assay, quantitative absorption and the protein A sheep red blood cell resetting assay.

The results obtained show that there is a population of surface IgM‐negative precursor B cells in young bone marrow which, when grown in vitro, become sequentially inducible for expression of B surface antigens. Inhibition of DNA synthesis promotes acquisition of the inducible state, and the sequence of antigen expression is correlated with specific time intervals after DNA synthesis has stopped.