Human interleukin-5 induces staphylococcal A Cowan 1 strain-activated human B cells to secrete IgM.
Studies on the role of human interleukin (IL)-5 in B cell growth and differentiation have yielded conflicting results. To clarify this issue, we studied the role of purified recombinant IL-5 on activated human B cells which were depleted of T cells and adherent cells. Human IL-5 augments IgM secretion, but not IgG or IgA secretion of purified human B cells activated with staphylococcal A Cowan 1 strain (SAC). However, the period of B cell activation with SAC is critical for the B cell to respond to IL-5. After 24 h of SAC activation, human B cells are responsive to the IL-5 signal, but with longer periods of activation, IL-5 responsiveness diminishes. This may explain some of the previous conflicting results. The IgM enhancement was not seen when B cells were activated with pokeweed mitogen. In addition, human recombinant IL-4 synergized with IL-5 in augmenting IgM secretion by SAC-activated B cells, while IL-5 synergized with IL-2 to augment IgM, IgG and IgA secretion by SAC-activated B cells. As the purified IL-5 was derived from a COS-1 cell supernatant, and COS-1 cells secrete IL-6, we examined whether a polyclonal IL-6 antibody blocked the IgM-enhancing activity of IL-5. IL-6 antibody did not block the IL-5 enhancement of IgM secretion, but a monoclonal antibody to IL-5 inhibited the human IL-5 activity on human B cells. These results demonstrate that human IL-5 augments IgM secretion of SAC-activated human B-cells. In addition, this lymphokine synergizes with IL-4 and IL-2 in supporting Ig secretion.
Bertolini
J N
JN
Department of Pathology and Immunology, Monash University Medical School, Alfred Hospital, Melbourne, Australia.
Sanderson
C J
CJ
Benson
E M
EM
D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D006801:Humans; D007075:Immunoglobulin M / Q000096:biosynthesis*; D007376:Interleukin-2 / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D015848:Interleukin-5 / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D013210:Staphylococcus / Q000276:immunology*
D000911:Antibodies, Monoclonal; D007075:Immunoglobulin M; D007376:Interleukin-2; D015848:Interleukin-5; D011994:Recombinant Proteins; D015847:Interleukin-4