Effect of dextran sulphate on IgG subclass of antibody in efferent popliteal lymph of sheep.

IgG1 and IgG2 participation in anti-hapten, anti-carrier and immunoglobulin-containing cell (Ig-cc) responses was studied in sheep immunised with killed Staphylococcus aureus-Dinitrophenyl (DNP) conjugates. The antigen was given with or without the polyanionic adjuvant dextran sulphate (DXS). Animals were immunised intracutaneously on the lateral hock of one hind leg with 1 X 10(9) S. aureus-DNP with or without 20 mg DXS. Six weeks later, primed sheep underwent surgery to cannulate an efferent popliteal lymphatic vessel in the immunised leg. Forty-eight hours after surgery, each sheep was given a further intracutaneous injection of 1 X 10(9) S. aureus-DNP with or without 20 mg DXS adjacent to the primary injection site. IgG1-cc and IgG2-cc in lymph were counted using indirect immunofluorescence. Total IgG1 and IgG2 anti-staphylococcal and anti-DNP antibody output in lymph was determined using enzyme-linked immunosorbent assays (ELISA's). DXS markedly increased antibody responses to S. aureus-DNP in the popliteal lymph node of sheep and was shown to strongly enhance immunological memory. The ratios of IgG2-cc:IgG1-cc and IgG2:IgG1 anti-staphylococcal antibody in lymph-draining popliteal lymph nodes of sheep stimulated with DXS and S. aureus-DNP was significantly greater than the same ratios in animals given antigen alone. The IgG subclass-specific immunomodulatory effects of DXS were exerted whether the adjuvant was given with primary and/or secondary inoculations. There was no difference in the ratio of IgG2:IgG1 anti-DNP antibody in lymph from animals given S. aureus-DNP with and without DXS.