In a prelminary communication, we described the establishment of a continuous human myeloid cell line (HL-60). Here we report the detailed properties of this cell line and document its derivation from the peripheral blood leukocytes of a patient with acute promyelocytic leukemia. As characterized by light and electron microscopy, the predominant cell type in both the fresh and cultured sources is a neutrophilic promyelocyte with prominent nuclear/cytoplasmic asynchrony. Up to 10% of the cultured cells spontaneously differentiate beyond the promyelocyte stage, and the proportion of terminally differentiated cells is markedly enhanced by compounds known to stimulate differentiation of mouse (Friend) erythroleukemia cells. The HL-60 cells lack specific markers for lymphoid cells, but express surface receptors for Fc fragment and complement (C3), which have been associated with differentiated granulocytes. They exhibit phagocytic activity and responsiveness to a chemotactic stimulus commensurate with the proportion of mature cells. As characteristic of transformed cells, the HL-60 cells form colonies in semisolid medium and produce subcutaneous myeloid tumors (chloromas) in nude mice. A source of colony-stimulating activity stimulated the cloning efficiency in soft agar 5--30-fold. Despite adaptations to culture, the morphological phenotype and responsiveness to chemical induction of differentiation is essentially unchanged through at least 85 passages. Cytogenetic studies reveal aneuploidy. Metaphases with 44 chromosomes predominated in vivo and in early culture passages; however, clones with 45 or 46 chromosomes became predominant with continued passaging. The most consistent karyotypic abnormalities were the deletion of chromosomes 5, 8, and X and the addition of a marker resembling a D-group acrocentric and of a submetacentric marker, most likely an abnormal E-group chromosome. No DNA herpesvirus or RNA retrovirus was isolated in the fresh or cultured cells. The HL-60 cultured cell line provides a continuous source of human cells for studying the molecular events of myeloid differentiation and the effects of physiologic, pharmacologic, and virologic elements on this process.

The leukemia from which the human cell line HL-60 was derived was classified in 1976 as acute progranulocytic leukemia (APL), although it was recognized to show a number of atypical features. In the ensuing 10 years, the concept of APL and its integral association with t(15;17) has evolved, and the concept of APL as a morphologically recognizable entity has become embodied in the term French-American-British classification M3 (FAB-M3). It is now recognized that not every case of leukemia with a high proportion of progranulocytes can be classified as FAB-M3. We reviewed the light and ultrastructural morphology of the original diagnostic material from this case, and we report that the leukemia from which HL-60 was derived does not conform to the currently recognized entity of FAB-M3 and is more appropriately classified as an acute myeloblastic leukemia with maturation, FAB-M2.

Massive and recurrent strandings of pelagic Sargassum biomass have become the new norm in the Caribbean and the Western Africa since 2011, and there is no sign of this abating. These Sargassum events have negative environmental, socioeconomic and health impacts in the affected countries. In the meantime, various processing techniques and applications have been suggested for valorisation of this biomass. However, variability in quantity, quality and location creates substantial uncertainty for the development of reliable and robust industrial processes. As part of ongoing efforts to better characterise seasonal and geographical variations in the biochemical and elemental composition of the pelagic Sargassum biomass across the Caribbean, we analysed samples from Mexico, Jamaica and the Dominican Republic harvested during summer 2020 and winter 2021. Different degrees of variation were observed in the contents of ash, metals and metalloids, vitamins, fatty acids, amino acids and biogenic amines, and monosaccharides. Our results indicate that biomass is of highly variable quality depending on season and location. In this context, we suggest that biorefinery approaches geared towards controlled metal removal and focused on the extraction and purification of amino acids, fatty acids and vitamins should be prioritised to assess the potential valorisation of pelagic Sargassum biomass into standardised and high-value outputs.

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Cytogenetic studies were performed in 546 patients with acute leukemia between 1968 and 1975. Two hundred thirty-four patients were aneuploid (42.9%), and 312 patients were diploid (57.1%). Among these, 32 patients were found to exhibit similar chromosomal alterations that appeared to involve specifically chromosomes 8 and 21. Banding studies in at least 15 of these patients confirmed the presence of a translocation between these two chromosomes. The cytogenetic findings were correlated with the hematologic and clinical data. It was found that each of these individuals had a typical picture of acute granulocytic leukemia with Auer rod-positive and peroxidase-positive cells. Ultrastructurally, the patients in this group also consistently demonstrated the presence of a nuclear bleb that has been positively associated with aneuploidy in acute leukemia. Clinically, they seemed to respond better to therapy than other adult patients with acute granulocytic leukemia. It is proposed that the 8/21 translocation acute leukemia represents a definite subgroup within the general category of acute granulocytic leukemia, with an incidence of approximately 7.3%.