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Cord blood plasma lipoproteins inhibit mitogen-stimulated lymphocyte proliferation
Insights
Cord blood lipoproteins, particularly those with apoprotein E, show a stronger capacity to suppress lymphocyte proliferation compared to adult lipoproteins. This finding highlights potential differences in immune regulation between newborns and adults.
Area of Science:
- Immunology
- Biochemistry
- Neonatal Research
Background:
- Lipoproteins play roles in cellular processes, including immune cell function.
- Differences in lipoprotein composition between adults and newborns may influence immune responses.
Purpose of the Study:
- To compare the immune-modulatory effects of adult and cord blood lipoproteins.
- To investigate the role of specific apolipoproteins in lipoprotein-mediated immune suppression.
Main Methods:
- Isolation of lipoproteins from adult and cord blood plasma.
- Assessment of lipoprotein inhibition of mitogen-stimulated lymphocyte proliferation in vitro.
- Quantification of apolipoproteins (AI, B, E) using radioimmunoassay.
- Selective removal of apoprotein E-containing lipoproteins via immunoaffinity chromatography and heparin-agarose adsorption.
Main Results:
- Cord blood low-density lipoproteins (LDL) and high-density lipoproteins (HDL) exhibited 2-4 fold greater inhibition of mitogen stimulation than adult counterparts at lower protein concentrations.
- A strong correlation was found between the inhibitory activity of cord blood lipoproteins and their apoprotein E content.
- Removal of apoprotein E-rich lipoproteins significantly reduced the suppressive activity of cord blood LDL and HDL.
Conclusions:
- Cord blood lipoproteins, especially those containing apoprotein E, possess a heightened ability to suppress lymphocyte proliferation in vitro.
- Apoprotein E, in conjunction with apoproteins AI or B, is a key factor in the immunomodulatory properties of neonatal lipoproteins.
Abstract:
Lipoproteins were isolated from adult plasma and the umbilical cord blood plasma of newborn infants and were compared for their capacity to inhibit mitogen-stimulated [3H]thymidine uptake of adult peripheral blood mononuclear cells in vitro. Relative to the comparable adult lipoproteins, cord blood low density lipoproteins and high density lipoproteins inhibited mitogen stimulation at twofold to fourfold lower total protein concentrations. Apoproteins AI, B, and E were quantitated by radioimmunoassay of each of the adult and cord blood lipoprotein fractions. A strong correlation was observed between inhibitory activity and the amount of apoprotein E in the cord blood low and high density lipoproteins. Further evidence that lipoproteins containing apoprotein E accounted for the difference in suppressive activity of cord blood low and high density lipoproteins relative to the adult lipoproteins was obtained by selective removal of the apoprotein E-containing lipoproteins by using immunoaffinity chromatography or heparin-agarose adsorption. The results indicated that cord blood lipoproteins containing apoprotein E in association with apoproteins AI or B are capable of suppressing lymphocyte proliferation in vitro.