The crossreactivity between the random synthetic
polypeptide antigen poly(Tyr,Glu)-poly(DLAla)--poly(Lys) [(
T,G)-A--L] and its ordered-sequence analogs (
Tyr-Tyr-Glu-Glu)-poly(DLAla)--poly(Lys) [(T-T-G-G)-A--L] and (
Tyr-Glu-Tyr-Glu)-poly(DLAla)--poly(Lys) [(T-G-
T-G)-A--L] at the level of humoral and cellular responses was studied. For delayed type
hypersensitivity responses, (
T,G)-A--L-activated T cells could be challenged with the homologous
antigen as well as with the ordered analogs. T cells activated by (T-T-G-G)-A--L could be challenged with either the homologous
antigen or with (
T,G)-A--L but not with (T-G-
T-G)-A--L. Similarly, no cross stimulation was observed between (T-G-
T-G)-A--L-activated cells and (T-T-G-G)-A--L, whereas (
T,G)-A--L could challenge the latter cells to mediate significant responses. Similar but not identical cross reactions were observed when primed spleen cells or lymph nodes were transferred to irradiated recipients that were boosted for the production of
antibodies. In contrast to observations at the level of cellular responses, (T-G-
T-G)-A--L-primed spleen or lymph node cells could not be boosted with (
T,G)-A--L for the production of detectable amounts of
antibodies, although boosting with the homologous
antigen resulted in significant levels of (T-G-
T-G)-A--L-specific
antibodies. Transfer experiments in which mixtures of T and B cells, each primed to a different ordered
polypeptide antigen, were injected into irradiated recipients showed that successful cooperation occurs provided that the boost is given with the T-cell-specific
antigen. The
antibodies produced were specific to the
antigen used for B-cell priming. The T-cell-B-cell collaboration probably occurs through specific determinants that are shared between the two
antigens in which the ordered
peptides are attached to the same multichain
polymer and that are recognized by both the T and the B cells.