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Semi‐Purification of an Immunosuppressor Substance Secreted by Streptococcus mutans that Plays a Role in the Protection of the Bacteria in the Host
Author(s) -
SANTARÉM M. M. G.,
PORTO M. T.,
FHRREIRA P.,
SOARHS R.,
ARALACHAVES M. P.
Publication year - 1987
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1987.tb02313.x
Subject(s) - immune system , bacteria , peripheral blood mononuclear cell , chemistry , isoelectric point , streptococcus mutans , microbiology and biotechnology , methylene blue , extracellular , biology , biochemistry , in vitro , enzyme , immunology , photocatalysis , catalysis , genetics
Crude extracellular products of Streptococcus mutans (CEP‐Sm) suppress the proliferative response to phytohaemagglutinin of human peripheral blood mononuclear cells and the primary immune response of C57BL/6 mice to sheep erythrocytes. This immunosuppressive effect favours the survival of the microorganism, and the bacteria lose the ability to secrete immunosuppressor substance if previously subcultured several times. Cells incubated with CEP‐Sm and subsequently washed recover the ability to proliferate. Traces of CEP‐Sm or too short a time of contact between CEP‐Sm and the target immune system induced higher proliferative ratios or higher in vivo immune responses than controls, respectively. The proliferative values of cultures supplemented with CEP‐Sm were parallel to the control values up to a certain time, after which they dropped abruptly. This drop is followed by a prolileration, and the higher the amount of CEP‐Sm added to the cultures, the shorter the time until the proliferation. CEP‐Sm was fractionated by means of ion exchange chromatography followed by double preparative isoelectrofocusing, ending in a subfraction of isoelectric point between 3.9 and 4.2, containing a heat‐unstable material stainable by Coomassie blue bui unstainable by periodic acid Schiff or methylene blue, and having a maximum optical density of 280 nm.