SLAMF7 and systemic lupus erythematosus: High levels of soluble SLAMF7 (sCS1) (91, 92) and increased mRNA of SLAMF7 in purified PCs have been documented in patients affected by monoclonal gammopathies in the entire spectrum, from monoclonal gammopathy of unknown significance (MGUS) through smoldering-, active-, and relapsed-refractory MM relapsed patients (93) and in autoimmune diseases, like systemic lupus erythematosus (94), or systemic infections in response to IFN-⍺ stimulation (80).