HBsAg Mediated Leukocyte Adherence Inhibition (LAI) and Its Immunologic Mechanism

Abstract

The leukocyte adherence inhibition (LAI) was studied in the hepatitis B viral infection and its immunologic mechanism was assessed. Leukocytes from 34 subjects with antiHBs in their serum (group A), leukocytes from 52 normal control subjects without any hepatitis B serologic markers (group B) and leukocytes from 26 subjects with HBsAg in their serum (group C) were tested against HBsAg as a specific antigen and BSA as a nonspecific antigen. The mean Non Adherence Index (NAI) of group A was significantly higher than that of group B or of group C (P < 0.001). The NAIs of 29 subjects (85.3%) among 34 subjects in group A were over 50 while only two subjects (3.8%) in group B and only one subject (3.9%) in group C were over 50. To determine whether soluble mediators such as leukocyte adherence inhibition factor (LAIF) or immunoglobulin produced by sensitized Iymphcytes were involved in the LAI response, supernatants collected from the peripheral blood leukocytes (PBL) after 24 hourincubation at 37°C with HBsAg (200 ug/ml) were assessed for adherence inhibition activity on normal PBL The supernatant collected following incubation of HBsAg with leukocytes obtained from anti HBs (+), LAI (+) subjects markedly reduced the adherence of the normal leukocytes. To determine the cell subfractions involved in the LAI assay, T and B cell enriched subpopulations were tested for LAI reactivity to HBsAg. The T cell enriched subpopulation gave positive LAI reactivity while the B cell enriched subpopulation gave no detectable LAI reactivity. To investigate serum factors of immune donors, the LAI-nonreactive leukocytes from normal control subjects or HBsAg carriers were preincubated with serum from LAI-reactive, antiHBs (+) subjects or with hepatitis B immune globulin (HBIG), and were tested for LA!. They showed positive LAI reactivity to HBsAg. The present study showed specific HBsAg mediated LAI assay and suggested that both two mechanisms, one dependent on specific antibody and the other on LAIF may be operated in hepatitis B virus antigen -antibody system.