Abstract
Complete reconstitution of Th cell function for B cell growth and differentiation was provided by plasma membranes (PM) derived from activated Th (PMAct) in combination with IL-4 and IL-5 (IL-4/IL-5). IL-5 has been shown to be essential for the secretion of all Ig isotypes by resting, conventional B cells activated by PMAct and IL-4. It was shown that in the presence of PMAct/IL-4/IL-5, a high frequency of resting B cells differentiated to express IgG1. IL-4 alone transiently induced the expression of germ-line γ1 transcripts. PMAct alone were ineffective at inducing germ-line γ1 transcript expression by resting B cells suggesting that Th-B cell contact was an insufficient signal to cause a detectable increase in the steadystate levels of γ1 germ-line transcripts. PMAct alone or PMAct/IL-4 did not induce the appearance of transcripts for secreted μ or mature γ1. IL-5, in combination with PMAct/IL-4, provided the necessary signal(s) required for the expression of secreted μ and mature γ1 transcripts. Therefore, IL-5 appeared to be an important if not essential differentiation factor for conventional B cells that have been activated by cognate help. It appeared that IL-5 promoted the secretion of Ig by inducing the synthesis of mature Ig transcripts.
Original language | English |
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Pages (from-to) | 1164-1169 |
Number of pages | 6 |
Journal | Journal of Immunology |
Volume | 149 |
Issue number | 4 |
State | Published - Aug 15 1992 |