HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Watanabe, S. Articles by Pressman, D. Search for Related Content PubMed Articles by Watanabe, S. Articles by Pressman, D.

Immunoglobulin Production in Synchronized Cultures of Human Hematopoietic Cell Lines

II. Variation of Synthetic and Secretion Activities During the Cell Cycle¹

From the Department of Biochemistry Research, Roswell Park Memorial Institute, ⁴ Buffalo, New York 14203

Abstract

Human lymphoid cells in established culture have been shown to synthesize immunoglobulins (Ig). Utilizing a lymphoid cell line (RPMI 1788) from a normal individual, we have now examined the synthesis and secretion of -IgM during various phases of the cell cycle. The cells were synchronized by double treatment with excess thymidine, or by a combination of treatments with thymidine and colcemid. After synchronization, the cells were collected at 1- or 2-hr intervals and pulse-labeled with ¹⁴C-leucine for 1 hr. The rate of IgM secretion was determined by assaying total IgM secreted during the pulse period. The rate of IgM synthesis was determined by specific precipitation of the labeled IgM which accumulated in the medium after culturing the pulse-labeled cells for an additional 24 hr in the regular medium. The results showed that there are two peaks of the synthetic activity during the cell cycle, one in the late G₁ or early S and the other in the G₂ phase. Thus, the expression of Ig genes appears to be limited to certain portions of the cell cycle as has been found for enzymes and other cell products. On the other hand, the rate of secretion does not vary as much during the cell cycle, although both the rate of synthesis and of secretion are at the lowest level in the mitotic phase.

Footnotes

¹ This work was supported in part by Grant AI-8472 from the National Institute for Allergy and Infectious Diseases.

² On leave of absence from the Institute for Cancer Research, Osaka University Medical School, Osaka, Japan.

³ Present address: Nippon Roche Research Center, Kamakura, Japan.

⁴ A unit of the New York State Department of Health.