Thrombopoietin, but not erythropoietin, directly stimulates multilineage growth of primitive murine bone marrow progenitor cells in synergy with early acting cytokines: distinct interactions with the ligands for c-kit and FLT3

Thrombopoietin (Tpo), the ligand for c-mpl, has been shown to be the principal regulator of megakaryocytopoiesis and platelet production. The ability of Tpo to potently stimulate the growth of committed megakaryocyte (Mk) progenitor cells has been studied in detail. Murine fetal liver cells, highly enriched in primitive progenitors, have been shown to express c-mpl, but little is known about the ability of Tpo to stimulate the growth and differentiation of primitive multipotent bone marrow (BM) progenitor cells. Here, we show that Tpo alone and in combination with early acting cytokines can stimulate the growth and multilineage differentiation of Lin- Sca-1+ BM progenitor cells. In particular, Tpo potently synergized with the ligands for c-kit (stem cell factor [SCF]) and flt3 (FL) to stimulate an increase in the number and size of clones formed from Lin- Sca-1+ progenitors. When cells were plated at 1 cell per well, the synergistic effect of Tpo was observed both in fetal calf serum-supplemented and serum-depleted medium and was decreased if the addition of Tpo to cultures was delayed for as little as 24 hours, suggesting that Tpo is acting directly on the primitive progenitors. Tpo added to SCF + erythropoietin (Epo)-supplemented methylcellulose cultures potently enhanced the formation of multilineage colonies containing granulocytes, macrophages, erythrocytes, and Mks. SCF potently enhanced Tpo-stimulated production of high-ploidy Mks from Lin- Sca-1+ progenitors, whereas the increased growth response obtained when combining Tpo with FL did not translate into increased Mk production. The ability of Tpo and SCF to synergistically enhance the growth of Lin- Sca-1+ progenitors was predominantly observed in the more primitive rhodamine 123(lo) fraction. Tpo also enhanced growth of Lin- Sca-1+ progenitors when combined with interleukin-3 (IL-3) and IL-11 but not with IL-12, granulocyte colony-stimulating factor, granulocyte-macrophage colony- stimulating factor, or Epo. Epo, which has high homology to Tpo, was unable to stimulate the growth of Lin- Sca-1+ progenitors alone or in combination with SCF or FL, suggesting that c-mpl is expressed on more primitive stages of progenitors than the Epo receptor. Thus, the present studies show the potent ability of Tpo to enhance the growth of primitive multipotent murine BM progenitors in combination with multiple early acting cytokines and documents its unique ability to synergize with SCF to enhance Mk production from such progenitors.     

Thrombopoietin, but not erythropoietin promotes viability and inhibits apoptosis of multipotent murine hematopoietic progenitor cells in vitro

The recently cloned c-mpl ligand, thrombopoietin (Tpo), has been extensively characterized with regard to its ability to stimulate the growth, development, and ploidy of megakaryocyte progenitor cells and platelet production in vitro and in vivo. Primitive hematopoietic progenitors have been shown to express c-mpl, the receptor for Tpo. In the present study, we show that Tpo efficiently promotes the viability of a subpopulation of Lin-Sca-1+ bone marrow progenitor cells. The ability of Tpo to maintain viable Lin-Sca-1+ progenitors was comparable to that of granulocyte colony-stimulating factor and interleukin-1, whereas stem cell factor (SCF) promoted the viability of a higher number of Lin-Sca-1+ progenitor cells when incubated for 40 hours. However, after prolonged (> 40 hours) preincubation, the viability- promoting effect of Tpo was similar to that of SCF. An increased number of progenitors surviving in response to Tpo had megakaryocyte potential (37%), although almost all of the progenitors produced other myeloid cell lineages as well, suggesting that Tpo acts to promote the viability of multipotent progenitors. The ability of Tpo to promote viability of Lin-Sca-1+ progenitor cells was observed when cells were plated at a concentration of 1 cell per well in fetal calf serum- supplemented and serum-depleted medium. Finally, the DNA strand breakage elongation assay showed that Tpo inhibits apoptosis of Lin-Sca- 1+ bone marrow cells. Thus, Tpo has a potent ability to promote the viability and suppress apoptosis of primitive multipotent progenitor cells.     

Adenosine deaminase activity in protein-energy malnutrition

Cell-mediated immunity (CMI) was evaluated in 69 children with protein-energy malnutrition (PEM) and 20 healthy controls. Significantly decreased responses to purified protein derivative (PPD) ( p < 0.02) and absolute lymphocyte count (ALC) ( p < 0.01) and increased serum adenosine deaminase (ADA) activity ( p < 0.001) were observed in PEM cases compared with the controls. The mean values of ALC and ADA activity in PEM patients were 85.9% and 158.7% of the normal mean, respectively. A significant negative correlation was observed between the two parameters ( r = −0.2765, p < 0.01). The CMI tests were abnormal in all three grades of PEM, except for the response to PPD in grade I, when compared with the controls. No significant differences were found between infected and uninfected PEM cases. Thus, impaired CMI was observed not only in grades II and III but also in grade I PEM patients and the concomitant infection did not affect its status. However, ADA activity demonstrated a more pronounced change than the other tests     

Congenital lobar emphysema

Congenital lobar emphysema, a life-threatening respiratory disorder presenting in infancy is best diagnosed by chest x-ray. Abnormality of bronchial cartilage is one of the suspected aetiological factors. Prompt lobectomy is the treatment of choice as conservative treatment carries an unacceptably high mortality and morbidity. One such patient, a 3-month-old child who underwent successful emergency left upper lobectomy is presented.     

Hallermann-Streiff-Francois syndrome

This is a typical case of Hallermann-Streiff-Francois Syndrome in which the glaucomatous complication may be caused by developmental malformations in the anterior segment of the eye. Bilateral trabeculectomy succeeded in controlling the tension after a follow-up of two years. Glaucomatous complication seems to be frequent and as important as the other described cardinal symptoms. The histologic examination of the skin confirmed the atrophic changes that were observed clinically.     

Desmoplastic melanoma: an updated immunohistochemical analysis of 40 cases with a proposal for an additional panel of stains for diagnosis

Desmoplastic melanoma (DM) is histologically characterized by a proliferation of spindle melanocytes dispersed in a collagenous stroma that can be mistaken for a variety of neoplasms. The purpose of this study was to analyze 40 cases of DM with a comprehensive panel of immunohistochemical markers (KBA.62, p16, Ezrin, WT‐1, MITF‐1, SOX‐10, CD117, SOX‐2, nestin, PNL2, p75, MART‐1, gp100 and S100p) to obtain a more complete understanding of the potential use of these antibodies in the diagnosis of DM. We found that all cases of DM expressed p16, WT‐1, SOX‐10, nestin and S100p and 95% of cases expressed p75. There was variable expression with Ezrin, SOX‐2, KBA.62, MART‐1 and HMB‐45. Most DMs did not express MITF‐1, PNL2 and CD117. Conditions that may enter in the histologic differential diagnosis of DM, including dermal scars, fibromatosis and dermatofibromas were also studied. Nearly all control cases also stained positive for p16 but were negative for WT1, SOX10, nestin, p75 and S‐100p, as well as for most of the other markers tested. We conclude that a panel of S‐100p, WT1, SOX10, p75 and nestin may constitute the optimal panel with the most sensitive and specific combination of immunostain available for the diagnosis of DM.     

Eruptive squamous cell carcinomas, keratoacanthoma type, arising in a multicolor tattoo

Permanent tattoos are formed through the injection of ink solids through the epidermis into the dermis and can cause multiple adverse reactions. We report a 38-year-old man who presented to our Dermatologic Surgery Unit with a diagnosis of a superficially invasive squamous cell carcinoma (SCC), keratoacanthoma (KA) type, of the left forearm in a 1-month-old tattoo. Since his initial biopsy, he developed four more similar lesions on his left forearm within his tattoo. On physical examination, the patient had a large, multicolor tattoo on his left forearm, a well-healed surgical biopsy site and four erythematous hyperkeratotic papules within differently pigmented areas of the patient's tattoo. Histopathological examination showed KA and tattoo pigment. Based on the eruptive nature of these lesions, their clinical presentation and the histopathological changes, we report this as the first case of eruptive KA arising in a multicolor tattoo.