Effect of anti-IgM MoAb affinity on potential to induce tyrosine phosphorylation of proteins designated as p137, p96, p78, and p60. Ramos B cells were stimulated for 1 or 5 minutes with the affinity-diverse anti-IgM MoAbs and the lysates analyzed as in Fig 5. The designated protein bands in the antiphosphotyrosine blots (eg, Fig5) were densitometrically analyzed as detailed in Materials and Methods. The results are expressed as the percentage of the maximal anti-IgM–induced protein tyrosine phosphorylation observed for each protein at a given time point. The mean ± SD of the percentage of maximum values for three separate experiments is shown. The paired Student’s t-test was used to evaluate whether the level of tyrosine phosphorylation of a given protein induced by MoAb HB57 (Ka = 55 × 107 mol/L−1) was significantly different from that induced by MoAb Mu53 (Ka = 2 × 107mol/L−1). P (probability) values that approached or were less than P = .05 are indicated above the bars representing the response to MoAb HB57.
