Immunology Letters, 31 (1991)73 - 78 Elsevier IMLET 01717 Flow cytometric analysis of the expression of murine B and T surface markers from birth to adulthood Louis E. King, Lorri A. Morford, Joseph P. Gibbons and Pamela J. Fraker Department of Biochemistry, Michigan State University, East Lansing, MI, U.S.A. (Received2 August 1991;accepted17 August 1991) 1. Summary The proportion of nucleated splenocytes bearing B-lymphocyte markers B220, surface IgM (slgM) and slgD, as well as the T-lymphocyte markers Thy 1.2, CD5, CD8a and CD4 were quantitated by flow cytometric analysis (FACS) throughout postpar- tum development in the A/J mouse. Full expression of B lymphocyte markers was achieved much soon- er than expression of T lymphocyte markers. This was especially true for B220, which was found on 8°70 of all splenocytes at day 5 and reached adult levels (47 - 50070)by weaning at day 22. Expression of slgM and slgD were 13°70 and 9070, respectively, of all splenocytes at day 5 with mature levels not expressed until day 35 postpartum (approximately 36°7o of cells were positive for these markers). T lymphocyte markers, on the other hand, did not reach full expression until sexual maturity. For ex- ample, Thy 1.2 expression was 8°7oon day 5 and did not reach mature levels (28- 30°7o) until day 56. CD5 closely paralleled Thy 1.2 expression rising from only 2°70on day 5 to 27°7o by day 56. Likewise, CD8a and CD4 marker development paralleled one another with CD8a rising from 1070on day 5 to 10°70 by day 56 and CD4 rising from 5°70 on day 5 to 19°70 by day 56. These data demonstrate the variability in the time of appearance and rate of maturation of the various lymphocyte cell surface markers during Key words: Splenicsurfacemarker development; T cell pheno- type; B cell phenotype; A/J mouse;FACS;Ontogeny Correspondence to: Dr. Pamela J. Fraker, Departmentof Bio- chemistry,MichiganState University,East Lansing, MI 48824, U.S.A. postpartum development. They also serve as a re- ference to identify alterations in lymphocyte devel- opment created by immunodeficiency diseases. 2. Introduction Identification of phenotypic cell surface markers that distinguish distinct lymphocyte subpopula- tions has become an invaluable tool. During neona- tal development, these surface markers arise in an asynchronous manner as growth and development of the immune system proceed. Understanding these phenotypic changes becomes crucial in deter- mining how diet and disease alter normal growth and development patterns. In the early 1970s, mi- croscopic analysis of fluorescent antibody labels provided vital information on the presence of vari- ous surface markers on a variety of adult leukocyte populations [1, 2]. Later these microscopic tech- niques were used to quantitate the proportion of a few T and B lymphocyte markers on various fetal and neonatal tissues [3- 8]. While these studies were useful in determining the onset and develop- ment of marker expression, their capacity to detect all positive populations was always limited. Flow cytometric analysis (FACS) has greatly increased the sensitivity of cell surface marker detection. By the early 1980s, FACS analysis was beginning to supply imp.ortant information on the ontological developme~at of a select number of murine T and B lymphocyte markers. Typically these studies exam- ined a few markers usually focusing on either B or T lymphocyte development [9- 14]. A comprehen- sive study which correlated the development of multiple murine T and B lymphocyte markers from 0165-2478 / 91 / $ 3.50 © 1991ElsevierSciencePublishers B.V. All rights reserved 73