Abstract
Pregnancy sera were found to react differently when screened simultaneously with adenoid and peripheral blood lymphocytes (PBL) obtained from the same individual. Some of the reactions were attributed to the higher sensitivity of adenoid lymphocytes to a low titer HLA or la antibody, while others were shown to be due to the expression of DRw(Ia-like) antigens on both T and B lymphocytes separated from adenoids. Positive reactions specific to adenoid lymphocytes, or manifested only following anti-β(2)-microglobulin (a-β(2)-m)treatment, suggest the presence of antigens other than HLA or la on the cell membrane. Unmasking of antigenic sites by the a-β(2)-m capping process and rearrangement of the membrane structure may also contribute to the observed phenomena.