Regulation of Ig Class Secretion by Soluble Products of Certain T‐Cell Lines

The Surprising Discovery That TGFβ Specifically Induces the IgA Class Switch

“…In 1989, when these two important papers were published, it was known that IL-4 directs LPS-activated B cells to switch to IgG1 and IgE (3)(4)(5). It was also known that, in the absence of added cytokine, B cells switch to IgG3 and IgG2b and that the addition of IFN-␥ induces IgG2a switching (6).…”

Immunoglobulin heavy-chain switching may be directed by prior induction of transcripts from constant-region genes.

“…Normal splenic B cells from mice will switch to IgG3 and IgG2b, and much less frequently to other isotypes, after polyclonal stimulation in culture with bacterial lipopolysaccharide (LPS) (1). Recently it has become clear that lymphokines produced by T cells can regulate class switching in these cultures.…”

“…Recently it has become clear that lymphokines produced by T cells can regulate class switching in these cultures. The addition of interleukin 4 (IL-4) to splenic B cells stimulated with LPS stimulates switching to IgG1 and IgE and markedly suppresses the switch to IgG3 and IgG2b (1)(2)(3). In contrast, LPS plus IL-5 promotes IgA, and LPS plus y-interferon promotes IgG2a responses (4)(5)(6).…”

Long lasting p53-specific T cell memory responses in the absence of anti-p53 antibodies in patients with resected primary colorectal cancer

“…In about 25 % of all colorectal cancer patients p53-specific IgG antibodies were detected before the tumor was removed and their presence is an indicator of poor prognosis [18,19]. The appearance of demonstrable levels of anti-p53 IgG antibodies in the blood of patients indirectly points to the existence of p53-specific CD4 + Th cells, since isotype switching to IgG is Th cell dependent [20,21]. Indications for spontaneously acquired p53-specific Th immunity in humans have recently been obtained by Tilkin et al [22] who demonstrated p53-specific proliferative responses in three breast cancer patients.…”