Covalent binding to immunogenic proteins increases the immunogenicity of the capsular polysaccharides of Haemophilus influenzae type b (Hib) and pneumococcus type 6A (Pn6A). Conjugates composed of Hib, Pn6A, or the cross-reacting Escherichia coli K100 covalently bound to tetanus toxoid (TT) were injected into young adult volunteers. Local reactions were common and were probably due to Arthus reactivity mediated by the preexisiting antibodies reacting with the TT component of the conjugates. Fever occurred in about 10% of the volunteers after the first injection; no volunteers had fever after the second injection. Similar levels of Hib or Pn6A antibodies were elicited by either 50or 100-,Ig doses or by concurrent injection of two different conjugates (Hib-TT and Pn6A-TT or Hib-TT and K100-TT). The Hib-TT elicited about a 180-fold increase in Hib antibodies, and the Pn6A-TT conjugate elicited about an 8-fold increase in Pn6A antibodies after one injection. Booster reactions were not elicited in adults; similar levels of antibodies in the five experimental groups suggested that the responses elicited by the conjugates were maximal. A one-way cross-reaction was noted as Pn6A conjugates elicited rises of Hib antibodies in 13 of 20 volunteers; only 4 of 59 volunteers immunized with Hib-TT had increases in Pn6A antibodies. The preimmunization Hib antibodies were composed of immunoglobulin M (IgM), IgA, and IgG. The postimmunization sera showed an increase in all three isotypes; the elevation of the IgG was the highest of the three isotypes. Conjugate-induced antibodies to both the polysaccharide and TT exerted biological activities that have been correlated with immunity. Adsorption of the Hib-TT onto aluminium hydroxide resulted in higher levels and an earlier Hib antibody response in infant rhesus. These results encourage the evaluation of Hib and Pn6A conjugates in human children and infants.
Normal human peripheral blood and tonsil lymphocytes can be stimulated to proliferate by phytohemagglutinin (PHA). When cells cultured with this mitogen for 3 days were transferred fo fresh autologous lymphocytes in fresh medium with PHA, the mitogen response of the fresh lymphocytes was suppressed. The suppression required the presence of viable cells, in that culture supernatants alone were not inhibitory and cell extracts showed only marginal inhibition. Approximately equivalent numbers of previously stimulated cells were required to produce optimal suppression of the PHA response of fresh cells. Cells irradiated after PHA stimulation were as effective as nonirradiated cells is causing suppression. PHA-stimulated cells also inhibited concanavalinA-induced proliferation and a mixed lymphocyte reaction. However, PHA-stimulated cells only partially inhibited the response to pokeweed mitogen. The suppressive effects were fully retained by a nylon-wool-enriched T-cell fraction but not by a B-cell-enriched fraction.
Rabbit lymphocytes have been analyzed as to surface Ig markers in relation to the function of the cells. A battery of specific anti-Ig reagents as well as supposed B and T cell-specific mitogens were used, and DNA synthesis as well as high-rate Ig synthesis in vitro were recorded. Using cells from spleen lymph node or blood, surface Ig-negative lymphocytes expressed the expected behavior of T lymphocytes. No evidence was found of significant expression of allotypic markers on the surface of such nonactivated rabbit T lymphocytes. Lymphoid cells from bone marrow constituted an exception to the rule in the sense that they contained a high proportion of cells being surface Ig-negative at the time of anti-Ig column fractionation. They did, however, rapidly express surface Ig molecules as well as B cell markers as judged by B cell mitogenic stimulation shortly after in vitro explanation. In conclusion, we failed to find any constant region Ig markers on rabbit lymphocytes, which in every sense behave like conventional T lymphocytes.
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