Vera Zakuth

Tuftsin and some analogs: synthesis and interaction with human polymorphonuclear leukocytes.

The phagocytosis-stimulating tetrapeptide tuftsin, L-threonyl-L-lysyl-L-prolyl-L-arginine, was synthesized by both conventional and polymeric-reagent approaches. Using a combination of the two methods several analogs were prepared, including: [Ala1]tuftsin, [Lys1]tuftsin, [Ser1]tuftsin, [Val1]tuftsin, acetyl-tuftsin, p-aminophenylacetyl-tuftsin and tyrosyl-tuftsin. [Des-Thr1]tuftsin and [omega-NO2(4)]tuftsin were synthesized using a conventional procedure. The effects of synthetic peptides on the phagocytosis of heat-killed yeasts and on the reduction of the dye nitroblue tetrazolium by normal human polymorphonuclear leukocytes were investigated. Tuftsin and to a lesser extent [Lys1]tuftsin and [Ser1]tuftsin were found to stimulate phagocytosis, whereas the other analogs synthesized as well as [Ser1]tuftsin exhibited inhibitory effects to tuftsins action. Tuftsin alone has stimulated nitroblue tetrazolium reduction; [Des-Thr1]tuftsin and [Ala1]tuftsin repressed this stimulation, while the other peptides showed no effect.

Specific binding sites for the phagocytosis stimulating peptide tuftsin on human polymorphonuclear leukocytes and monocytes

Abstract Highly purified and biologically active [3H]tuftsin (specific activity 9 Ci/mmol) was synthesized and its binding to several types of human circulating blood cells was studied at 22°C. The binding to polymorphonuclear leukocytes and to monocytes was found to be specific, fast, saturable and reversible. Values for the dissociation constants (KD) were derived from equilibrium experiments and are 130 and 125 nM, respectively. The number of binding sites is approximately 50,000 and 100,000 per cell, respectively. Under the same experimental conditions lymphocytes exhibited only a threshold binding capacity for [3H]tuftsin whereas erythrocytes revealed no detectable binding.

Dialysis-Induced Eosinophilia

Blood eosinophils were counted by the counting-chamber method in 21 regular hemodialysis patients. Before dialysis, eosinophil counts were within the normal range in all patients (mean 98 cells/mm3, range 6-350). After the first 15 min of hemodialysis, with not reused coils or hollow-fiber dialysers, a significant drop in eosinophil counts was noted in all patients. The mean drop was 37.5% of the initial value (range 28-100%). At the end of the 5-hour dialysis, the eosinophil counts rose significantly in all patients but 1. The mean rise was 521% of the initial counts (range 22.3-1576%). Simultaneous neutrophil counts showed the already described drop at 15 min with a return to predialysis levels at 5 h. Predialysis IgE serum concentrations were lower than normal (mean 24.8, range 4.5-58 units/ml), and did not change at the end of the dialysis. It seems that pulmonary sequestration is responsible for both neutropenia and eosinopenia early in dialysis. The marked eosinophilia at 5 h may be the result of a release of eosinophilotactic substances induced by the dialysis procedure itself.

Acquired tuftsin deficiency.

Galen’s declaration that the spleen is an organ full of mystery continues to be appropriate despite the passage of time and advances in medicine. For centuries it was believed that the spleen is not physiologically essential and that removal of the spleen does not lead to any harmful consequences. During the last decades, splenectomy has been widely used as the treatment of choice for both trauma and various hematological disorders. This approach, termed by Morgenstern’ “the surgical inviolability of the spleen,” was challenged by King and Schumacher in 1952.2 They published their observation that splenectomy performed in infants exposes them to serious bacterial infections. This observation focused interest on the role of the spleen in immunity and infection. Overwhelming sepsis later has also been reported in adults even many years after ~plenectomy.~ The incidence of sepsis after removal of the spleen for trauma (0.5-1%) is considerably lower than that following elective splenectomy. It is today widely accepted that the increased susceptibility to fulminant infections of splenectomized patients is a result of detrimental consequences of removal of an organ of major importance in maintaining defence mechanisms against bacteria. Not all immune functions were sufficiently clarified, but it was agreed that the spleen plays a particularly important part in controlling the phagocytic capacity of polymorphonuclear leukocytes. This was first suggested in an elegant and precise work documented by Najjar and his group from Tufts University.’ They have found defective phagocytosis in the leukocytes of humans and animals who have undergone splenectomy and attributed this defect to the absence of tuftsin, a basic tetrapeptide (L-Thr-L-Lys-L-Pro-L-Arg) produced or released in the spleen, that acts as a phagocytosis-stimulating agent of both polymorphonuclear leukocytes and macro phage^.^ Tuftsin has been synthesized and the biological activity of the synthetic substance and its equivalence to the natural peptide have been shown in vitro and in vivo by various assaysss6 and in various systems.’ We have developed a radioimmunoassay for measuring serum tuftsin concentra-

Serum immunoglobulin A levels and ethnicity in an Israeli population sample

Serum IgA concentrations were measured in 1799 healthy Israeli military recruits (698 women and 1101 men) using an automated nephelometric system. The overall prevalence of IgA deficiency defined at a level of less than 50 mg/liter was 1.0 +/- 0.46% (95% confidence limits). No significant difference was found between the sexes in the mean values of serum IgA. Statistically significant ethnic differences were evident. Recruits of European origin had lower serum IgA concentrations than the North African, Israeli, or Asian origin groups. Whether the apparently high prevalence of IgA deficiency in this young population in Israel has clinical significance is at present unknown.

Studies on the activity of phorbol myrystate acetate on the human polymorphonuclear leukocytes

Phorbol myrystate acetate (PMA) activates nitroblue tetrazolium reduction in human polymorphs. The activation is inhibited by dibutyryl cyclic AMP, theophylline and phenylbutazone, but is not influenced by hydrocortisone in vitro, nor is it inhibited by leukocytes from patients treated with prednisone. Peptide analogues of Tuftsin also had no effect on this stimulatory activity. We conclude that the action of PMA on the nitroblue tetrazolium reduction is mediated through cyclic nucleotides.

The Immune System Response to Campylobacter Infection

Campylobacter may be one of the most common causes of bacterial gastroenteritis (GE) in children. It has recently been suggested that it is one of the bacterial pathogens most likely to infect immune‐compromised children, and it may facilitate colonization of enteric pathogens. The immune system response was studied in 12 children with Campylobacter fetus subspecies jejuni (CBJ) infections. Serum concentrations of IgA, IgM, and IgG were analyzed using a Beckman auto‐analyzer. Sera specific Ab to CBJ were tested with CBJ specific enzyme‐linked immunosorbant assay (ELISA). Mitogen stimulation of lymphocytes was performed to three lectins: Con A, PWM, and PHA. The lymphocyte blast transformation to Campylobacter was studied using the Campylobacter antigen. T‐cell subsets were studied using the monoclonal antibodies Leu 2, 3, and 4 (Becton Dickinson). Chemotaxis was measured in modified Boyden chambers; chemotactic stimulants were the Formyl Met Leu Phe, Campylobacter antigen virion, and E. coli 0111 B. Immunoglobulins were normal in nine cases and abnormal in two children previously diagnosed as agammaglobulinemic and one diagnosed as hypoagammaglobulinemic. Specific serum Ab level was significantly higher in the CBJ group, except in the agammaglobulinemic group. Stimulation indices to mitogens and monoclonal subset were in the normal range. The blastogenic transformation to CBJ Ag was decreased compared to normal lectins, and positive and high compared to controls. The chemotactic activity to campylobacter Ag was decreased in comparison to other stimulants. Most CBJ infections are self‐limiting due to a normal immune response and collaboration of all cellular limbs. When, however, the immune response is disturbed, we may find a prolonged and complicated course of CBJ.