Osmotic stress and the freeze-thaw cycle cause shedding of Fc and C3b receptors by human polymorphonuclear leukocytes

A major problem in the cryopreservation of human polymorphonuclear leukocytes (PMN) is the loss of phagocytic function in cryopreserved cells. This is not a problem with cryopreserved monocytes. To study the reasons for this difference in detail, PMN and monocytes were either osmotically stressed in hypertonic media or were frozen to various temperatures. Cells were then returned to conditions of physiologic osmolarity and temperature. All cells remained viable. However, the ability of PMN to phagocytize bacteria and to bind sheep erythrocytes (E) opsonized with IgG, C3b, or C3bi decreased sharply after exposure to media of 600 mOsM or greater and after freezing to -1.5 degrees C. In contrast, monocytes were unaffected until a concentration of 1500 mOsM or a freezing temperature of -5 degrees C was exceeded. To determine whether the functional losses of surface receptor activity in PMN resulted from a loss of receptors from the membranes or from inactivation or internalization of receptors, opsonized E were incubated in the supernatants from stressed PMN. On subsequent incubation with healthy PMN, these E made fewer rosettes than control opsonized E. The inhibitory effect of the supernatants on rosetting of IgG-sensitized E could be removed by preincubation with IgG bound to Sepharose 4B. Immunoprecipitation of C3b and C3bi receptors from surface-iodinated, osmotically stressed, and control PMN suggested that about 50% of cell surface complement receptors were lost from the cell surface during osmotic stress. These experiments suggest that receptors for IgG and C3 are extruded from PMN cell membranes as a result of hyperosmotic stress, which is associated with the freeze-thaw cycle. This may be an early event in the functional damage done to PMN during attempts at cryopreservation.

Osmotic stress and the freeze-thaw cycle cause shedding of Fc and C3b receptors by human polymorphonuclear leukocytes

A major problem in the cryopreservation of human polymorphonuclear leukocytes (PMN) is the loss of phagocytic function in cryopreserved cells. This is not a problem with cryopreserved monocytes. To study the reasons for this difference in detail, PMN and monocytes were either osmotically stressed in hypertonic media or were frozen to various temperatures. Cells were then returned to conditions of physiologic osmolarity and temperature. All cells remained viable. However, the ability of PMN to phagocytize bacteria and to bind sheep erythrocytes (E) opsonized with IgG, C3b, or C3bi decreased sharply after exposure to media of 600 mOsM or greater and after freezing to -1.5 degrees C. In contrast, monocytes were unaffected until a concentration of 1500 mOsM or a freezing temperature of -5 degrees C was exceeded. To determine whether the functional losses of surface receptor activity in PMN resulted from a loss of receptors from the membranes or from inactivation or internalization of receptors, opsonized E were incubated in the supernatants from stressed PMN. On subsequent incubation with healthy PMN, these E made fewer rosettes than control opsonized E. The inhibitory effect of the supernatants on rosetting of IgG-sensitized E could be removed by preincubation with IgG bound to Sepharose 4B. Immunoprecipitation of C3b and C3bi receptors from surface-iodinated, osmotically stressed, and control PMN suggested that about 50% of cell surface complement receptors were lost from the cell surface during osmotic stress. These experiments suggest that receptors for IgG and C3 are extruded from PMN cell membranes as a result of hyperosmotic stress, which is associated with the freeze-thaw cycle. This may be an early event in the functional damage done to PMN during attempts at cryopreservation.

Plasma fibronectin enhances phagocytosis of opsonized particles by human peripheral blood monocytes

We have investigated the effect of plasma fibronectin (Fn) on binding and phagocytosis of sheep erythrocytes (E) by human peripheral blood monocytes. Unopsonized E were not phagocytosed in the absence or presence of Fn, but Fn enhanced the phagocytosis of E bearing IgG. Sheep erythrocytes sensitized with IgM and C3b were ingested only when monocytes were exposed to Fn. The Fn enhancement of phagocytosis occurred for both fluid-phase and glass-adherent monocytes. Experiments in which Fn was washed out before mixing monocytes with opsonized E demonstrated that the Fn effect occurred because of interaction with the monocytes and not the opsonized particles. Chromatography of the Fn on Biogel A 1.5m showed that the phagocytosis-enhancing activity exactly co-chromatographed with the Fn protein. Fn did not increase the number of monocyte membrane receptors for the Fc fragment of monomeric IgG. We conclude that Fn enhances monocyte phagocytosis, not by binding to particles as a conventional opsonin, but by stimulating monocytes to ingest already opsonized particles more avidly.

The precipitating antibody to an acidic nuclear protein antigen, the Jo-1, in connective tissue diseases. A marker for a subset of polymyositis with interstitial pulmonary fibrosis

The clinical significance of antibodies to the Jo-1 antigen in connective tissue diseases was studied. Clinical diagnoses of 11 patients who had anti-Jo-1 antibody were: polymyositis 8, dermatomyositis 1, and overlap syndrome 2 (polymyositis--systemic lupus erythematosus 1, polymyositis--scleroderma 1). All the patients who had anti-Jo-1 antibody showed interstitial pulmonary fibrosis, and in 2 patients anti-Jo-1 antibodies were detected before the appearance of lung disease.

C3d receptors are expressed on human monocytes after in vitro cultivation

Highly purified human third component of complement (C3) was used to coat sheep erythrocytes (E) that were sensitized with IgM antibody (EA), forming EAC3b over a wide range of C3 molecules per cell. EAC3b were converted to EAC3bi by incubation with purified C3b inactivator (factor I) and beta 1H globulin (factor H). EAC3bi were in turn trypsinized to produce the cellular intermediate EAC3d. Each of the cell types was carefully characterized to be certain of the type of C3 determinant expressed. These cellular complement intermediates were used to assess by rosette formation the C3 receptor activity on peripheral blood monocytes under various experimental conditions. Uncultivated monocytes from peripheral blood bound EAC3b and EAC3bi well but did not bind EAC3d significantly. However, upon cultivation on glass surfaces in the presence of fetal calf serum but not bovine serum albumin, monocytes showed a progressive increase in expression of the C3d receptor. The Fab' fragment of anti-C3c blocked binding of EAC3b completely, blocked EAC3bi partially, but failed to block binding of EAC3d to cultivated monocytes. In contrast, the Fab' fragment of anti-C3d blocked EAC3d rosette formation completely. These studies demonstrate that monocytes are capable of expressing receptor activity for a determinant on C3d but that the expression of this receptor depends on the state of activation or differentiation of the cells.

Morphological study on the hereditary neurogenic amyotrophic dogs: accumulation of lipid compound-like structures in the lower motor neuron

A morphological study was performed on hereditary neurogenic amyotrophic dogs, the clinical features of which especially resembled spinal progressive muscular atrophy (SPMA), a human motor neuron disease. The skeletal muscles showed obvious neurogenic atrophy with endomysial fibrosis. The peripheral nerves revealed axonal degeneration mainly limited to the motor nerve. In the spinal cord, the number of anterior horn cells seemed normal but, interestingly enough, numerous accumulated granules were detected in these anterior horn cells. Histochemically, these granules were interpreted as a lipid compound. Under the electron microscope, the granules were disclosed as multi-lamellar structures, arranged concentrically or in parallel, resembling membranous cytoplasmic bodies (MCBs) or zebra bodies. This finding strongly suggests that hereditary abnormality of lipid metabolism may underlie SPMA in these dogs. However, unlike other metabolic disorders where accumulations of granules are diffusely distributed, in the dogs we examined accumulations were found only in the anterior horn cells of the spinal cord and in the hypoglossal and spinal accessory nuclei. We are unable to explain this occurrence at the present time. Further investigations should be made on dogs because they serve as an important animal model of human motor neuron disease.

Determination of dihydroergot alkaloids in serum by radioimmunoassay

A radioimmunoassay for dihydroergotoxine was developed using antiserum frm the rabbit injected with a dihydromethylergometrine-bovine serum albumin conjugate. The antiserum was found to be highly specific to dihydroergot alkaloids. The minimum detectable amount of dihydroergotoxine methanesulfonate with this assay system was about 100 pg/ml in serum. Practical applicability of the assay system was proved by measuring dog serum concentrations after oral administration of dihydroergotoxine methanesulfonate.

Characterization of a high molecular weight acidic nuclear protein recognized by autoantibodies in sera from patients with polymyositis-scleroderma overlap

Autoantibodies in the serum from a patient with connective tissue disease have been used to define a high molecule weight acidic nuclear protein antigen. The antigen tentatively termed Ku, after the first two letters of patient's name, has distinct physicochemical properties and immunological specificities that distinguish it from previously reported antigens. The Ku antigen has an apparent 300,000 mol wt as determined by gel filtration and sucrose density gradient ultracentrifugation techniques. The antigen is destroyed by trypsin, mild heating, and pH variations greater than 10 and less than 5. Treatment with ribonuclease or deoxyribonuclease did not affect the antigenic reactivity. The Ku antigen was demonstrated in the soluble extracts of human, calf, and rabbit, but not of rat tissues. Purified antibody localized the Ku antigen within the nuclei of human liver where a "reticular" pattern of immunofluorescence was seen. Of 330 patients with various connective tissue diseases, 9 had precipitating antibodies to the Ku antigen. Preliminary results of clinical analysis indicated that antibody to the Ku antigen might become a useful marker for a group of patients with clinical characteristics of both polymyositis and scleroderma with a good prognosis.

Sensory nerve conduction velocities in the cutaneous afferents of the ulnar and peroneal nerves of the dog: tissue temperature-dependent reference ranges

Sensory nerve conduction velocities in the cutaneous afferents of the ulnar and peroneal nerves of the neurologically normal adult dog were determined by stimulation at stimulus intensities of 15, 20 and 25 V through subcutaneously placed electrodes and by the averaged evoked response technique. Stimulus intensities of 15 V for the ulnar nerve and 20 V for the peroneal nerve were adequate to measure the sensory nerve conduction velocities of these nerves. A linear relationship was seen between sensory nerve conduction velocity (y in m/s) and tissue temperature (x in degree C) and the regression equations were expressed as follows: y = 1.6x + 12.3 at a stimulus intensity of 15 V for the ulnar nerve and y = 2.0x - 10.6 at 20 V for the peroneal nerve, respectively. The 95% confidence limits of the regressions of the sensory nerve conduction velocities against tissue temperature, obtained at a stimulus intensity of 15 V for the ulnar nerve or at a stimulus intensity of 20 V for the peroneal nerve, were proposed for a tissue temperature-dependent reference range to enable the clinician to evaluate graphically the sensory nerve conduction velocity in a diseased dog.