Virgin T cells do not provide help for antigen-specific B cells in the absence of IL-4, IL-5, and IL-6

1 September 1991

journal article
research article
Published by Oxford University Press (OUP) in International Immunology

Vol. 3 (9) , 907-916
https://doi.org/10.1093/intimm/3.9.907

Abstract

We have used a mAb, 23G2, directed against the B exon of the murine CD45 molecule to identify and separate two subpopulations of normal peripheral CD4+ T cells. Examination of these two subpopulatlons indicates that they correspond to virgin (T_v) (CD45R_Bhl) and memory (T_m) (CD45R_B10) cells. In this report we have determined the abilities of T_v and T_m cells to provide antigen-specific, cognate help to hapten-specific antigen-binding B cells. To this end we have enriched T_v and T_m cell populations from splenic CD4+ T cells and have cultured these cells with TNP-specific antigen-binding cells (TNP-ABCs) and specific antigen. We then examined the ability of T_v and T_m cells to promote Ig secretion by the B cells. Both T_m and T_v cells Interact with antigen-presenting B cells as assessed by proliferation and lymphoklne secretion. However, T_m, but not T_v, cells promote substantial Ig secretion by TNP-ABCs in the presence of antigen. When either IL-6 or IL-4 plus IL-5 are added to cultures of T_v cells, B cells and antigen, Ig secretion is restored. Thus, T_v cells Interact effectively with B cells to Induce an activation signal, but in the absence of IL-4 plus IL-5 or IL-6 lymphoklnes, which are not secreted by T_v cells, these cells do not provide help for an antibody response. Hence, naive, peripheral T_v cells must undergo an antigen-dependent differentiation step into T_m and secrete IL-4, IL-5, and IL-6 before they can Induce B cells to secrete antibody.

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