Two distinct types of helper T cells involved in the secondary antibody response: independent and synergistic effects of Ia- and Ia+ helper T cells.

Abstract

Since the original discovery of T-and B-cell collaboration in the antibody response, it has been generally accepted that the helper T cell represents a single subset in the multimember family of T cells. There are, however, some controversial findings on the nature of the help with respect to its specificity, class preference, and genetic restrictions. In the antibody response to a hapten.carrier conjugate, the helper T cell is believed to recognize the carrier determinant and then to help antibody synthesis by B cells which recognize another determinant (hapten) linked to the same molecule. This type of interaction is supported by a phenomenon known as the carrier effect, in which the hapten-specific secondary antibody response is successfully elicited by the hapten coupled to the same carrier by which animals have been primarily immunized (1-4). A similar cooperative interaction between hapten-specific B cells and carrier-specific T cells is readily demonstrable in the adoptive secondary antibody response (5-8). Since in these cases hapten and carrier determinants must be present on a same single molecule, the T-B collaboration should occur upon recognition of the hapten by B cells, and recognition of the adjacent carrier determinants by T cells in a cognate form.There are certainly no denials of the presence of this type of interaction. Nevertheless, there are several examples in which the cognate interaction is not likely to occur in certain T-cell-dependent antibody responses. In fact, various antigen-nonspecific factors derived from T cells can trigger the B-cell response, in which the factors themselves do not recognize carrier determinants (9-13). Several investigators are also aware that the hapten-specific B cells can be triggered under certain circumstances in which B and T cells are independently stimulated by corresponding determinants present on two distinctly separate molecules (8,12,14,15). Hence, cognate interaction is not the only pathway for the effective T-B cell collaboration. One could ask whether the same or different helper T cells are involved in these diverse pathways of T-B cell collaboration.Such problems are now even more complicated by the growing evidence suggesting that the helper T cell may recognize not only the carrier determinants, but also the products of major histocompatibility gene complex (MHC).

Regulatory mechanisms in immune responses to heterologous insulins. II. Suppressor T cell activation associated with nonresponsiveness in H-2b mice.

“…These primed T cells are Lyt-l+2 -, I-J-, which is consistent with the helper T cell phenotype described in other systems (25,26,31). These Lyt-1 ÷, 2-, I-J-helper cells are dependent upon hapten-carrier linkage to stimulate antibody responses, which is typical of classically defined, cognate helper T cells (27)(28)(29). The fact that these Th cells are radioresistant supports the conclusion that they are primed, not virgin, T cells (30).…”

“…T cells have been shown to collaborate with B cells using at least two different pathways (27)(28)(29). Experiments were performed next to determine whether pork insulin-primed Th cells act through classical helper mechanisms or through bystander mechanisms.…”

Hapten‐Specific T Cell Response to Azobenzenearsonate‐N‐Acetyl‐L‐Tyrosine (ABA‐tyr) in Lewis Rats: II. Induction and Suppression of ABA‐Specific Helper Cell Activity for Antibody Production

“…The results in Table 7 show that ABA-BSA alone or a mixture of ABA-BSA and TNP-BSA generates a small increase in anti-TNP PFC but nothing like the effect seen when both haptens are on the same molecule. Presumably the stimulation of ABA-specific T cells by ABA-BSA might induce the release of nonspecific helper factors (10), leading to the increase observed, or two types of helper T cells like what was shown by several investigators (18,25,31) might exist. Our results with hapten conjugates of D-and i.-pclypeptides support and extend previous studies on DTH with similar materials (4,20).…”

Interleucina-17 como Alvo Terapêutico na Psoríase

“…As células T podem apresentar diferentes caracterís-ticas que as classificam em subclasses com funções distintas, tais como os linfócitos T-helper CD4+ e os linfócitos T citotóxicos CD8+. Os primeiros linfócitos T-helper a serem descritos incluíam apenas dois tipos, Th1 e Th2, 17 mediadores da imunidade celular e humoral, respectivamente. Ambos derivam de uma mesma linhagem celular comum, os linfócitos T-helper naive, e caracterizam-se por padrões de citocinas específicas a cada um desses subtipos.…”