Detection and spontaneous alteration of lymphocyte antigens on slide smears

Smears of cell suspensions from murine lymphoid organs were preppared on slides, air dried, and processed for detection of immunoglobulin (Ig) and theta (Thy-1) antigens by the unlabeled antibody peroxidase-antiperoxidase (PAP) technique. Satisfactory results were obtained for both antigens on recently made smears. However, slides kept at room temperature showed a progressive decrease in staining of the two antigens with time. Various fixatives and preservation procedures were tested to prevent this alteration. Good conservation of smears was obtained when slides were kept at -18‡C and/or air isolated before or after fixation with alcohols. A similar degradation of Ig and/or Thy-1 antigens occurred also in histological tissue sections or in serum spots dried on slides. The major cause for this degradation is thought to be contact with air, residual enzymatic hydrolysis playing a less important role.