Reconstitution of natural cell-mediated cytotoxicity with specific antibodies

The apparent nonselective reactions of natural cell-mediated cytotoxicity (NCMC) are selective when tested by inhibition of cytotoxicity with competitor cells indicating a recognition of specificities by the effector cell. N cells that mediate this NCMC in humans have most of the characteristics of K cells that mediate antibody-dependent, cell-mediated cytotoxicity (ADCC) and possess Fc receptors. IgG antibodies attached loosely to N cells through their Fc region, form part of the class of lymphocytes with surface immunoglobulin. We hypothesized that ADCC and NCMS involved similar mechanisms but with the specificity of NCMC directed by the natural IgG antibodies already attached to N cells. Removal of the antibodies with trypsin and reconstitution with specific anti-HLA antibodies produced specific effector cells supporting the role of antibodies on N cells as directors of specificity in NCMC.

Determination of specificity in natural cell-mediated cytotoxicity by natural antibodies

Natural cell-mediated cytotoxicity (NCMC) and antibody-dependent cell-mediated cytotoxicity (ADCC) appeared to involve similar cytotoxic mechanisms; effector N-cells killed target cells with IgG antibodies attached to the Fc receptor determining the specificity of the reaction. In NCMC the wide range of specificities detected by natural antibodies provided an effector system capable of recognizing numerous antigens on cultured target cells. When several target cells were tested concurrently, an apparent nonselective cytotoxicity resulted. The specificity of individual reactions against each of the target cells could be demonstrated by selective inhibition with competitor cells. The inhibition of cytotoxicity by competition and the effect of proteases on the effector cell for NCMC, but not for ADCC, initially suggested an antibody on the surface of the natural cytotoxic effector cell. This suggestion was supported by the loss of activity with treatments that removed immunoglobulins on the effector cell and by the recovery of reactivity with incubation of the cells in normal human serum. Absorption of the reconstituting serum with target cells resulted in loss of activity against that target cell, substantiating the role of natural antibodies.

B cell antigens on effectors for natural cell-mediated cytotoxicity

Cell suspensions enriched for N cells, the effector cell for human natural cell-mediated cytotoxicity, were observed to react strongly with a rabbit antiserum directed against an antigen associated with B cells. Treatment of the effector suspension with the antiserum resulted in inhibition of natural cell-mediated cytotoxicity. The blocking occurred, however, only with the intact antibody indicating that inhibition was caused through the formation of antigen-antibody complexes. The antiserum was then employed to arm natural effector cells to react specifically with B cell lines. Specific arming was achieved after the formation of antigen-antibody complexes was prevented by initially reacting the effector suspension with F(ab')2 of the anti-B cell antibody. This study also supports the identity of the subset of cells responsible for antibody-dependent and natural cell-mediated cytotoxicity and the similarity in their mechanisms.

A transient increase in renal clearance of phosphate in response to continuous infusion of salmon calcitonin in rats

The effects of intravenous carrier-free salmon calcitonin on renal clearances of phosphate, calcium, magnesium, sodium and potassium were studied in male parathyroidectomized (PTX) and intact rats. Both natural and synthetic hormone, when infused at constant rates (0.005 approximately 0.5 MRC U/hr), produced a rapid increase (peaking at about 60-90 min) in phosphate clearance. However, the maximal increase was transient in nature in PTX rats. In intact rats, the phosphaturic response was somewhat more pronounced and the decline after the peak was rather modest. When a large amount (4 MRC U) of calcitonin was given in divided doses, the second dose produced a lesser extent of phosphaturia in both intact and PTX rats. The phosphaturic response was accompanied by an increase in sodium and potassium clearances in PTX rats and by an increase in potassium clearance in intact rats. A fall in the apparent clearance values for calcium and magnesium occurred and was maintained throughout the infusion period of hormone in both intact and PTX rats. In conclusion, PTX rats respond to the intravenous administration of salmon calcitonin with a transient phosphaturic response which is accompanied by parallel diuresis of sodium and potassium along with sustained retention of calcium and magnesium by the kidney.

Successful replacement of a thrombosed Björk-Shiley mitral valve prosthesis

A case is presented in which 7 months after the first mitral valve replacement (MVR) the malfunction of a Björk-Shiley valve prosthesis was supposed and the thrombosed valve prosthesis was 2 months later successfully replaced. For the detection of the malfunction of the valve prosthesis echocardiography was especially useful.

Distinct target determinants on two lymphoblastoid lines derived from the same individual1

Specifically cytotoxic cells were generated in undirectional mixed leukocyte culture against both T and B lymphoblastoid cell lines. The cytotoxicity observed included both specific and less selective components which were differentiated by the interaction analysis based on the two-way analysis of variance. The results indicate that a T cell line and a B cell line derived from the same person possessed distinct target specificities. The antigens detected by direct cytotoxicity were confirmed by inhibition studies with competitor cells.

A transient increase in renal clearance of phosphate in response to continuous infusion of salmon calcitonin in rats

The effects of intravenous carrier-free salmon calcitonin on renal clearances of phosphate, calcium, magnesium, sodium and potassium were studied in male parathyroid-ectomized (PTX) and intact rats. Both natural and synthetic hormone, when infused at constant rates (0.005 approximately 0.5 MRC U/hr), produced a rapid increase (peaking at about 60-90 min) in phosphate clearance. However, the maximal increase was transient in nature in PTX rats. In intact rats, the phosphaturic response was somewhat more pronounced and the decline after the peak was rather modest. When a large amount (4 MRC U) of calcitonin was given in divided doses, the second dose produced a lesser extent of phosphaturia in both intact and PTX rats. The phosphaturic response was accompanied by an increase in sodium and potassium clearances in PTX rats and by an increase in potassium clearance in intact rats. A fall in the apparent clearance values for calcium and magnesium occurred and was maintained throughout the infusion period of hormone in both intact and PTX rats. In conclusion, PTX rats respond to the intravenous administration of salmon calcitonin with a transient phosphaturic response which is accompanied by parallel diuresis of sodium and potassium along with sustained retention of calcium and magnesium by the kidney.