ANTI-CD45 AUGMENTS RESPONSE OF A T(H)2 CLONE TO TCR CROSS-LINKING

The CD45 molecule is a transmembrane tyrosine phosphatase that may be associated with the T-cell receptor (TCR). This has led to the suggest ion that CD45 may be important for the regulation of signal transducti on in T cells. This idea is supported by the finding that antibodies a gainst CD45 are comitogenic in proliferation assays. In the present wo rk, we have examined the comitogenicity of CD45 antibodies by studying the effect of CD45, CD45RA, and CD45RB monoclonal antibodies (MoAbs) on proliferation of D10 cells induced with T-cell receptor (TCR) MoAbs . In addition interactions with some other proliferation inducing agen ts namely CD3 antibodies, lectins, and IL-2, are examined here. We hav e found that in general the CD45 MoAbs would significantly enhance pro liferation induced by a wide spectrum of TCR MoAbs and other prolifera tion inducing agents, with some minor quantitative differences. The CD 45 and CD45RB MoAbs were equally potent in their comitogenic activity while the CD45RA antibody was somewhat less potent. The comitogenic ef fect was maximal when CD45 antibodies were added simultaneously with t he TCR MoAb, but significant comitogenicity could be detected when CD4 5 MoAbs were added up to 24 h after the initiation of the culture indi cating that the CD45 antibodies also affect other processes than the i nitial signal transduction cascade.