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Biomedical subjects

H S Lawrence

Publications and source records attributed to H S Lawrence.

At least 37 records · Page 2Linked to original sources
PubMed1977

A microculture system for the measurement of antigen-induced murine lymphocyte proliferation: advantages of 5% horse serum and 5 X 10(-5) M mercaptoethanol.

Short term microculture systems which measure murine lymphocyte proliferative responses to mitogens are well established. We demonstrate here that these microculture methods are not suitable for antigen-induced responses because of the high levels of murine lymphocyte proliferation in control cultures associated with the use of fetal calf serum or human serum. We also show that this problem can be eliminated with the use of a combination of 5% horse serum and 5 X 10(-5) M mercaptoethanol. We describe an antigen-induced murine lymphocyte proliferation microculture system in which good stimulation indices are achieved and the lymphocyte proliferation in control cultures remain at a low level throughout the 7 day culture period.

Animals↗
PubMed1977

Concentrations of levamisole required for enhanced proliferation of human lymphocytes and phagocytosis by macrophages.

We studied the in vitro effects of levamisole on phagocytosis by macrophages and on proliferation of lymphocytes obtained from human peripheral blood. It was observed that levamisole directly stimulated phagocytosis in a lymphocyte-free system. Enhancement was optimal at a concentration that inhibited antigen- or mitogen-induced stimulation of sensitive lymphocytes. Lower concentrations of levamisole enhanced the proliferative lymphocyte response.

Dose-Response Relationship, Drug↗
PubMed1977

In vitro augmentation of lymphocyte sheep cell rosette formation by leukocyte dialysates.

We have studied in vitro the effects of leukocyte dialysates containing transfer factor on the formation of sheep cell rosettes by human lymphocytes. Dialysate had no effect on the toral rosettes, but increased the number of rapidly forming ("active") rosettes. This was due to an increased affinity of the lymphocytes for the sheep red cell. Trypsin-treated lymphocytes regained the ability to form rosettes more rapidly when cultured with leukocyte dialysates than with control media. These experiments suggest that leukocyte dialysate acts to increase the number or arrangement of sheep cell receptors on the lymphocyte surface.

Cell Membrane↗
PubMed1976

Requirement of precommitted cells as targets for the augmentation of lymphocyte proliferation by leukocyte dialysates.

After our initial report tha leukocyte dialysates containing transfer factor augment the thymidine incorporation of antigen-stimulated lymphocytes, we have adapted the system to microleukocyte cultures. This modification permits both (a) the simultaneous assay of a single dialysate on the cells of multiple individuals, and (b) the assay of multiple dialysates on the cells of a single individual. The data thus secured, demonstrate that dialysates from both skin-test-positive and -negative donors produced similar degrees of augmentation whether the data are expressed as an arithmetic difference or as a ratio. When expressed as an arithmetic difference, the amount of augmentation is increased in proportion to the level of thymidine incorporation of the assay cells when they were stimulated by antigen alone. When expressed as a ratio, however, the degree of augmentation is independent of the response of the assay cells. An analysis of the ability of dialysates to engage previously uncommitted lymphocytes and thus to augment thymidine incorporation, revealed that precommitted cells were required. In these experiments, antigen-reactive cells were deleted from populations of peripheral blood lymphocytes by incubation with purified protein derivative of tuberculin, diphtheria toxoid, or streptokinase-streptodornase in the presence of [3H]thymidine of high specific activity. This deletion depressed or abolished the effect of dialysate on the residual population when it was recultured with the same antigen, but the effect on the response of the remaining lymphocytes to other antigens was unaltered. In this study, leukocyte dialysate appeared to augment nonspecifically the thymidine incorporation of an antigen-specific precommitted clone of lymphocytes. The relationship of these adjuvant effects on peripheral blood lymphocytes in vitro to the specific and nonspecific activities of transfer factor in vivo remains to be elucidated.

Adjuvants, Immunologic↗
PubMed1976

A micromethod for evaluating the phagocytic activity of human macrophages by ingestion of radio-labelled polystyrene particles.

Studies in vitro of human macrophage function in health and disease have been impeded by the difficulty of obtaining such cells in sufficient number. Unlike animal species, the only readily available source of human macrophages are circulating monocytes. Herein, a method is described whereby the phagocytic rate of small numbers of glass-adherent mononuclear cells can be accurately measured. The method utilizes the ingestion by macrophages of technetium labelled polystyrene particles; both the radiolabel and ingestible substrate are readily available and the labelling process simple and efficient. The phagocytic rate can be expressed as radioactive counts per microgram of cell protein; data is also presented showing that the number of particles ingested per cell can be accurately derived.

Blood Cell Count↗
PubMed1975

Histocompatibility studies in a closely bred colony of dogs. V. Mechanisms of cellular adaptation in long-term DL-A identical radiation chimeras.

20 Cooperstown beagles of known DL-A genotypes (B" dogs) were exposed to supralethal total body irradiation and received a bone marrow allograft from a DL-A identical donor (A" dog); the resulting chimeras have survived uneventfully for 882, 1466 days, with no evidence of secondary disease, and have been tolerant to kidney and skin allografts obtained from the donor of marrow. Treatment of "A" dogs with serum obtained from their long-term "B" chimeras had no significant effect upon the ability of the recipients to reject "B" skin allografts...

Animals↗
PubMed1975

In vitro epidermal cell proliferation in rat skin plugs.

Full-thickness skin plugs from immature and adult rats have been shown to incorporate -3H-thymidine in vitro in a semisynchronous fashion for up to 54 hr. DNA synthesis is minimal at 16 hr post sacrifice but increases again at 24 and 48 hr, and cells in S phase at 48 hr have passed through at least one mitosis in vitro (between 32 and 39 hr). Advantage can be taken of this semisynchronous burst of DNA synthetic activity to test the effects of potential inhibitors of skin cell proliferation, and to determine at which phase of the cell cyclic these inhibitors act. High concentrations of epinephrine or isoproterenol (10--5 M) are required to cause inhibition but the effect is specific for the G2 phase of the cell cycle. Propranolol does not demonstrate beta-antagonism in this system, since it is a very potent inhibitor acting in G1 phase. Dibutyryl cycle AMP and theophylline have two effects: one is a specific inhibitory action on cells in the G2 phase and the second is a short-term action limiting thymidine uptake by cells in S phase without affecting the transition of cells from G1 to S.

Aminophylline↗
PubMed1974

In vitro properties of leukocyte dialysates containing transfer factor.

The chief impediment to the precise biochemical identification of transfer factor and its mechanism of action has been the lack of a reproducible in vitro assay. We now report on a method by which dialysates containing transfer factor of proven in vivo potency can convert nonimmune lymphocytes to immune responsiveness in vitro, as reflected by antigen-triggered lymphocyte proliferation. However, "water-dialyzed transfer factor" (TF(D)) prepared for in vivo use by the conventional method of dialysis against large volumes of water exhibits diminished activity in vitro and is frequently toxic to lymphocyte cultures. This problem can be avoided by dialysis of transfer factor into tissue culture medium. When this precaution is taken, such "media-dialyzed transfer factor" (TF(DM)) causes nonimmune lymphocytes to respond to antigen by an increment of thymidine incorporation that ranges from 2 to 25 times that of such cells cultured with antigen alone. This response is generally observed only in the presence of those antigens to which the TF(DM) donor expresses delayed cutaneous reactivity and is distinguishable from nonspecific adjuvant effects.

Adjuvants, Immunologic↗
PubMed1974

Effects of dialyzable transfer factor in patients with breast cancer.

Five patients with advanced breast cancer were treated with pooled dialyzable transfer factor from healthy adult donors. The period of treatment ranged from 21 to 310 days, the total dose from 20 to 257 ml. Transfer factor did not elicit inflammatory or hypersensitivity reactions or detectable formation of antibody to itself, nor any hematological or biochemical abnormalities or other side effects. Three patients became responsive (by skin test) to tuberculin and/or streptococcal antigens. Marked partial regression of the breast cancer, lasting 6 months, was observed in one patient.

Adult↗