Selective effects of cholera toxin on the activation of mouse B cells by different polyclonal activators.
Murine B cells were stimulated in vitro with anti-immunoglobulin (Ig) antibodies, lipopolysaccharide, or with various combinations of phorbol dibutyrate and ionomycin. Very low concentrations (ca. 10(-14) M) of cholera toxin inhibited anti-Ig-stimulated DNA synthesis, while the response to LPS was only abrogated by 2 X 10(4)-10(5)-fold greater concentrations of the toxin. Earlier responses in anti-Ig-stimulated B cells, such as increases in Ia antigen levels, were not affected by the toxin. Protein kinase C-activating phorbol esters, together with Ca2+ ionophores, are believed to stimulate DNA synthesis in lymphocytes by mimicking the two second messengers resulting from ligation of the antigen receptors. However, concentrations of cholera toxin which totally abolish anti-Ig-induced B cell proliferation significantly enhanced DNA and RNA synthesis induced by phorbol dibutyrate plus ionomycin. The results are discussed in terms of possible effects of cholera toxin on guanine nucleotide-binding (G) proteins controlling receptor coupling to second messenger-generating systems in B cells.
Klaus
G G
GG
National Institute for Medical Research, Mill Hill, London, GB.
Vondy
K
K
Holman
M
M
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology*; D002772:Cholera Toxin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000502:physiology; D004247:DNA / Q000096:biosynthesis; D004987:Ethers / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology*; D007152:Immunologic Capping / Q000187:drug effects; D015759:Ionomycin; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D004987:Ethers; D008070:Lipopolysaccharides; D010703:Phorbol Esters; D011947:Receptors, Antigen, B-Cell; D010566:Virulence Factors, Bordetella; D015240:Phorbol 12,13-Dibutyrate; D015759:Ionomycin; D004247:DNA; D002772:Cholera Toxin; D000242:Cyclic AMP; D019204:GTP-Binding Proteins