I hope you can provide me with some insight. :)
I exposed a B lymphoma cell line with LPS in vitro for some toxicity tests. And today I was just wondering how long the effect of a mitogen would last if it were no longer present in the medium and if I just kept on passaging the cells.
In the body, lymphocytes get stimulated and proliferate. Most chapters or articles I read are focusing on the activation of the cells and the mounting of the adaptive immune response. But what happens after the pathogen is dealt with? Are the cells self-regulating to stop the proliferation or are other parts of the immune system taking care of that!
Thanks in advance!
Dear Christine,
Your question is very interesting. The following paper might give you insight into this topic,
http://www.ncbi.nlm.nih.gov/pubmed/287831
J Natl Cancer Inst. 1979 Aug;63(2):413-21.
Long-term effects of neonatal estrogen treatment on mitogen responsiveness of mouse spleen lymphocytes.
Kalland T, Strand O, Forsberg JG.
Abstract
Neonatal female NMRI mice were given injections of olive oil (controls) or daily doses of corticosterone (10 micrograms), 17 beta-estradiol (10 micrograms), or diethylstilbestrol (DES) (0.01, 0.1, 1, or 5 micrograms) for the first 5 days after birth. The 5-micrograms dose of DES resulted in a persistently reduced in vitro mitogen response to concanavalin A or bacterial lipopolysaccharide of spleen lymphocytes from 6-, 10-, and 18-week-old or 17-month-old females. DES injections from day 6 through day 10 did not influence the later mitogen response. Treatment of ovariectomized 10-week-old females with 5 micrograms DES for 5 days resulted in a tendency to a reduced mitogen response (not statistically significant) 24 hours after the last DES injection. Four weeks later, the mitogen response was the same in experimental and control females. Different possible mechanisms for the persistent effect on the mitogen response are discussed. Neonatal DES treatment not only resulted in persistent changes in the cervicovaginal epithelium and in the hypothalamic-pituitary gland control system but also in the spleen lymphocyte mitogen response. The altered mitogen response should be a stimulus for a detailed analysis of the immune system in women exposed to DES during fetal life, some of whom develop later in life clear cell adenocarcinoma of the uterine cervix and vagina.
Hoping this will be helpful,
Rafik
The effect of the mitogen per se may not last that long, but once the cells started proliferating, the cytokine produced by them keep them going. If you do [3H]-thymidine incorporation assays using ConA stimulated T cells (so starting with a defined number), the cells keep going for up to a week, before being burned out (and undergoing apoptosis), In vitro, there is a lot of interefrences from other cytokines (IL-10, TGFb), other cells, and within stimulated cells, you will have activation of SOCS at given timepoints as well. In addition, that may nt be fully applicable for B cells, T cells need more than one signal to proliferate, otherwise they develop anergy.
Hope that helps
Dirk
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