Human recombinant IL-3 is a growth factor for normal B cells.
IL-3 is a well known hemopoietic cell growth and differentiation factor. However, its functional role in normal B cell differentiation has not been established. We have investigated the effect of IL-3 on the growth and differentiation of human B cells. IL-3 enhanced the proliferation of Staphylococcus aureus Cowan 1 strain-stimulated B cells. The optimal time of IL-3 to stimulate B cell growth was on day 2 to day 3, suggesting that IL-3 was a B cell growth factor acting in the late stage. IL-3 synergized with IL-2 to enhance B cell proliferation and differentiation. Pretreatment of B cells with IL-3 for more than 3 days increased the expression of IL-2R on B cells. However, pretreatment of B cells with IL-2 did not alter the subsequent response to IL-3, suggesting that the synergy between IL-2 and IL-3 may be attributed to the up-regulation of IL-2 response by IL-3. In addition, pretreatment of B cells with IL-4 decreased subsequent response of B cells to IL-3 as well as IL-2, suggesting that IL-3- and IL-2-responding cells passed a similar way during the early stage of B cell activation. It appears that IL-3 and IL-6 mediate normal B cell differentiation via separate mechanisms. IL-3-induced B cell differentiation was mainly mediated by increasing cell growth, whereas IL-6 induced B cell differentiation without affecting proliferation.
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Alton Ochsner Medical Foundation Laboratory of Cellular Immunology, New Orleans, LA 70121.
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D001402:B-Lymphocytes / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D004357:Drug Synergism; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D007377:Interleukin-3 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D015375:Receptors, Interleukin-2 / Q000032:analysis; D011994:Recombinant Proteins / Q000494:pharmacology
D006133:Growth Substances; D007376:Interleukin-2; D007377:Interleukin-3; D015850:Interleukin-6; D015375:Receptors, Interleukin-2; D011994:Recombinant Proteins; D015847:Interleukin-4