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Biomedical subjects

H G Opitz

Publications and source records attributed to H G Opitz.

25 records · Page 2Linked to original sources
PubMed1976

Adjuvant and suppressor activity of the polycation protamine hydrochloride in the primary immune response of mice.

The effect of protamine hydrochloride (PH), a polycation, on the primary immune response of mice to sheep red blood cells (SRBC) was studied. Like other adjuvants, PH enhances or depresses the immune response depending on the time of injection of PH in relation to the antigenic challenge. The suppressive effect of PH correlated with the appearance of "activated" macrophages in the peritoneal cavity. A second injection of PH together with antigen abolished this suppressive effect. Transfer of "activated" macrophages resulted in an enhanced immune response when antigen was administered at the time of transfer, and in a depressed response when the antigen was given 1 or 2 days after transfer. It is concluded that the duration of the influence of "activated" macrophages on T or B cells determines the subsequent immune reactivity. It is discussed that the basic mechanism of action of PH is its ability to release lysosomal enzymes from macrophages. The mechanism by which these enzymes amplify the immune response remains to be clarified.

Adjuvants, Immunologic↗
PubMed1976

Function of 2-mercaptoethanol as a macrophage substitute in the primary immune response in vitro.

The mechanism by which 2-ME acts as a macrophage-substitute for the induction of a primary PFC response to SRC in vitro was studied in macrophage-depleted mouse spleen cell cultures. 2-ME could replace macrophages only in FCS-supplemented cultures. Evidence is presented that the function of 2-ME is independent of residual macrophages. Neither normal nor macrophage-depleted spleen cell cultures from congenitally athymic nude mice supplemented with 2-ME, with or without FCS, could give rise to a primary in vitro anti-SRC immune response. 2-ME, at an optimal concentration of 10(-5) M, induced DNA synthesis in normal and macrophage-depleted spleen cells in both FCS-containing and serum-free cultures. The peak response occurred on day 3. The stimulation was accompanied by a polyclonal B cell activation to antibody secretion which was much more pronounced in FCS-containing than in serum-free cultures. Spleen cells from nude mice showed a weaker DNA stimulation than did cells from normal mice in FCS-containing cultures, and nearly no response under serum-free conditions. T cells obtained by a nylon column adherence method from normal mouse spleen cells showed good DNA synthetic responses in FCS-containing, but no response in serum-free cultures. These results show that 2-ME has weak mitogenic activity for B cells, and in combination with FCS, strong mitogenic activity for T cells. Since the macrophage provides stimulation to the T cell in the primary anti-SRC PFC response in vitro, these results suggest that the direct mitogenic activity of 2-ME with FCS on T cells provides the functional substitution for macrophages.

Animals↗
PubMed1975

Macrophages suppress direct B-cell activation by lipopolysaccharide.

The influence of macrophages on polyclonal B-cell responses to lipopolysaccharide (LPS) and on a primary, specific immune response to a hapten-LPS conjugate was studied in mouse spleen and lymph node cells in serum-free and serum-supplemented cultures. Macrophages were found not to be necessary, and B cells were directly activated by LPS. In serum-free cultures of macrophage-depleted spleen cells, (a) proliferation and antibody secretion occurred at normal levels or were enhanced when compared with normal spleen cells, (b) the responsiveness of limiting cell numbers to LPS was better than in normal spleen cell cultures, (c) LPS did not increase the number or activate residual macrophages, (d) the primary specific response to a hapten-LPS conjugate developed normally, (e) peripheral lymph node cells, which are known to contain a very low concentration of macrophages, from normal or congenitally athymic (nude) mice mounted excellent proliferative responses to LPS. Furthermore, in cultures supplemented with fetal bovine serum, depletion of adherent cells resulted in enhancement of LPS-induced B-cell responses. Addition of peritoneal macrophages to adherent cell-depleted spleen cells produced suppression at all concentrations of both mitogen and adherent cells. Suppressive activity could also be demonstrated in supernatants from adherent cell cultures stimulated by LPS.

Animals↗