Inhibition of MLC stimulator function by antibodies directed to non-HLA antigens.

The properties of five human alloantisera which inhibit the stimulating capacity of cells in an MLC reactions are described. All of the sera showed patterns of inhibition in families which did not correlate with HLA haplotypes. In a large proportion of the families investigated the sera did not react with parental cells but inhibited the cells from one or more of the children. Absorptions were performed with one of these sera using such non-reactive parental cells. Paternal cells absorbed out the inhibiting activity while maternal cells did not. This indicates that expression of the antigen with which the inhibiting antiserum reacts is insufficient for inhibition and other factors, either environmental or inherited from the mother, influence the capacity of the antiserum to cause inhibition. This antigen was most likely a non-HLA antigen.