Immunoregulation of B lymphocyte colony formation by T cell subsets in
patients with chronic lymphocytic leukemia
LA Fernandez, JM MacSween and GR Langley
Normal B lymphocytes are activated, proliferate, and then differentiate
into plasma cells and secrete immunoglobulin (Ig). We have reported that
chronic lymphocytic leukemia (CLL) T4 cells help and CLL T8 cells lack
suppressor effects on Ig synthesis by normal B cells (Blood 62:767, 1983).
We have now explored the earlier phase, proliferation, using B cell colony
formation; in semisolid media. B lymphocyte colonies from normal
individuals and from patients with CLL were grown in 0.3% agarose overlayed
with T cells or T cell subsets and the B cell mitogen staphylococcal
protein A. Enriched T cells, OKT4 or OKT8, were obtained either by sheep
erythrocyte rosettes or depletion of OKT8 or OKT4 cells by monoclonal
antibody or complement, respectively. Twenty thousand B cells from normal
subjects yielded 65 +/- 9, 64 +/- 7, and 19 +/- 6 colonies with autologous
unfractionated T-, OKT4-, or OKT8- positive cells, respectively. This
compared to 29 +/- 11, 81 +/- 11, and 15 +/- 4 colonies from patients with
CLL with added autologous unfractionated T-, OKT4-, or OKT8-positive cells.
To determine whether the fewer number of colonies in both normal subjects
and patients with CLL with OKT8-positive cells was due to suppression or
lack of help, the number of OKT4-positive cells was held constant, and
OKT8-positive cells were added in increasing numbers. No suppression of
colony formation could be demonstrated. Furthermore, the addition of
increasing numbers of concanavalin A (Con A)-activated OKT8-positive cells
did not suppress colony formation. These results suggest that the CLL T
cell subsets behave in a functionally similar manner to normal T cell
subsets, namely, (1) that normal and CLL B cell colony growth is helped by
OKT4 cells; and (2) in contrast to immunoglobulin secretion by B cells,
neither normal nor CLL OKT8 cells, unstimulated or activated by Con A,
suppress B cell colony growth.
Volume 67,
Issue 2,
pp. 294-298,
02/01/1986
Copyright © 1986 by The American Society of Hematology