THE REACTION OF ANTILYMPHOCYTE SERUM WITH LYMPHOCYTES: I. The Blocking of Surface-Associated γ-Globulin

Abstract

SUMMARY

The reaction of antilymphocyte serum (ALS) with lymphocytes in vitro was studied using the technique of reverse immune cytoadherence (RICA) which detects surface γ-globulin through the formation of rosettes. ALS was shown to block the detection of γ-globulin in 30–40% of mouse spleen lymphocytes as shown by inhibition of rosette formation. The blocking was detected only at high dilutions of ALS, beyond those of cytotoxicity or opsonization. Low dilutions were ineffective (prozone). 7 S or 19 S fractions used separately can also block the surface γ-globulin, but only at very low dilutions, while they were ineffective at high dilutions. Recombination of 7 S and 19 S fractions in concentrations equivalent to those of serum reproduced the blocking observed at high dilutions with the unfractionated serum. However, the recombination mixtures do not show prozone at low dilutions in contrast to the original serum. The blocking of the surface γ-globulin with 7 S and 19 S at high dilutions occurs only when both are present within a narrow range of optimal proportions. If these results represent a mechanism of “blindfolding,” they indicate that this can be achieved by extremely small amounts of ALS and is effective by a synergistic effect of 7 S and 19 S fractions of the ALS which must be present in optimal proportions.