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Expression of HLA and CD1b molecules was investigated in the THP-1 macrophage cell line within 2 weeks following phagocytosis of mycobacteria or Escherichia coli. During the first 2-3 days, cell surface expression of HLA class II and CD1b was drastically down-modulated, whereas HLA class I expression was up-modulated. In the following days both HLA class II and CD1b expression first returned to normal, then increased and finally returned to normal with kinetics similar to that observed for the steadily increased HLA class I. The initial down-modulation of HLA class II and CD1b cell surface antigens was absolutely dependent on phagocytosis of bacteria. Further studies indicated that initial HLA class II cell surface down-modulation (1) was not due to reduced transcription or biosynthesis of mature HLA class II heterodimers, (2) was only partially, if at all, rescued by treatment with IFN-gamma, although both mRNA and corresponding intracellular proteins increased up to sixfold with respect to untreated cells, and (3) resulted in failure of THP-1 cells to process and present mycobacterial antigens to HLA-DR-restricted antigen-specific T cell lines. The existence of a transient block of transport of mature HLA class II heterodimers to the cell surface in the first days after phagocytosis of bacteria may have negative and positive consequences: it decreases APC function early but it may increase it later by favoring optimal loading of bacterial antigens in cellular compartments at high concentration of antigen-presenting molecules.

It is generally believed that the various MHC class II molecules are expressed coordinately in B cells. To investigate this aspect in more detail, interspecies somatic cell hybrids were constructed between Raji or RJ 2.2.5 (a class II-negative derivative of Raji) human B cells and M12.4.1 mouse B cells. In both types of hybrids, HLA-DR and -DP, but not -DQ, molecules were expressed at the cell surface. The specific lack of expression of DQ Ags correlated with undetectability of newly synthesized DQ alpha beta heterodimers, as assessed by biosynthetic labeling and immunoprecipitation with a variety of DQ-specific mAbs. Studies at the mRNA level showed that apparently normal DQ alpha and DQ beta transcripts were present in the hybrids at levels comparable, if not higher, with the levels of DR- and DP-specific transcripts. From these results, we conclude that lack of appreciable amount of DQ molecules in the hybrids is caused by a post-transcriptional block. To date, these findings represent a rather unique example of noncoordinate expression of MHC class II Ags caused by distinct post-transcriptional mechanisms. These data may be relevant to a more correct interpretation of the functional role of the various MHC class II molecules, particularly with regard to the well-known association of HLA-DQ with many autoimmune diseases. Possible mechanisms at the basis of the distinct control of expression within the MHC class II molecular pool are discussed.

Gli AA. hanno studiato il comportamento del glutatione ridotto eritrocitario ed iltest di stabilita in 35 soggetti diabetici. I valori del glutatione ridotto sono risultati nei diabetici inferiori ai normali mentre iltest di stabilita non appare modificato. Non esiste un rapporto tra il livello del glutatione e la durata, il tipo, la gravita del diabete. Nessuna relazione e stata riscontrata tra livello del glutatione ed iltest di stabilita da un lato, il livello glicemico e la glutationemia dall'altro.

Sulfhydryls were determined in the serum of 61 patients affected with malignant hemolymphopathies. The mean values were under normal, except for the group of acute leukemias. A particularly marked difference was found between primary acute leukemias and acutizations of chronic myeloid leukemias. In the former, normal mean values and, in most cases, normal initial values were observed, whereas in the latter no cases with normal initial values were found: here, in addition, the lowest mean values were present. In these cases a relation was observed between lowering of sulfhydryl value and degree of the leukemic hyperplasy. In Hodgkin's disease the lowest sulfhydryl values were found to be consistent with a shorter survival.

Gli AA. hanno studiato la glicolisi eritrocitaria in 50 soggetti diabetici sottoposti a diverse terapie. Considerando tutti i casi, i valori della glicolisi (espressi in mg/100 ml di globuli rossi/h) non si discostano significativamente dai normali. Nei diabetici esiste tra glicemia iniziale e glicolisi una correlazione significativa che si discosta dai normali poiche, a parita di valori glicemici, la glicolisi e orientata nei diabetici verso cifre nettamente inferiori. La gravita del diabete e il tipo di trattamento non sembrano influire sulla significativita delle correlazioni. Vengono discussi gli eventuali rapporti tra diabete e metabolismo eritrocitario.

Basing on the significance of sulfhydryl groups in cell metabolism, the behaviour of serum sulfhydryls was studied in various physiological and pathological conditions. The limiting values of the normal ranges were assessed. Pregnancy, fever, anemia, decay of general conditions were not found to cause an abnormal shift in sulfhydryl values. On the other hand, in cancer patients sulfhydryls are often under the normal, although a 26 per cent of normal values may be observed in the presence of clinically demonstrated cancers: hence, the determination of serum sulfhydryls is not of diagnostical value. This different behaviour, likely dependent on the varying rate of sulfhydryls linked to globulins, was not found to be consistent either with the site and extent of the tumour, or with the presence of metastases, or with the duration of the disease.